This document discusses advance plant breeding techniques, including molecular breeding (marker assisted selection) and micro-propagation. Molecular breeding uses DNA markers linked to desirable traits to assist in selecting plants with those traits, without needing to phenotype the traits directly. Marker assisted selection allows for more breeding cycles in a year and pyramiding of multiple resistance genes. Micro-propagation, also called clonal propagation, involves propagating plants vegetatively in vitro to produce clones that are genetically identical to the original plant.
1) Synthetic and composite varieties are developed in cross-pollinated crops by mixing seeds from multiple parental lines and allowing open-pollination.
2) Synthetic varieties are produced by evaluating parental lines for general combining ability and mixing seeds in a controlled manner, while composite varieties simply mix seeds without evaluating parental lines.
3) Both synthetic and composite varieties allow farmers to use saved seed for a few years and are maintained by open-pollination, providing more yield stability than hybrids.
This document discusses the development of inbred lines through repeated self-pollination and selection over multiple generations. It describes how inbred lines are developed from variable source populations in both self- and cross-pollinated crops using methods like pedigree selection. Inbred lines are homozygous genotypes that are then used to produce hybrid varieties which benefit from heterosis or hybrid vigor. The document outlines the procedures for inbred line development and some of the early hybrid varieties released for important crops in India.
The document discusses three methods for selecting pure lines from crosses in self-pollinated crops: pedigree method, bulk method, and single seed descent method.
The pedigree method involves selecting individual plants from segregating generations and tracking their offspring through generations until homozygosity is achieved. The bulk method involves growing segregating generations in bulk until homozygosity, then selecting individuals. The single seed descent method rapidly advances generations by growing only one seed per plant in each generation to achieve a random sample of homozygous lines.
Marker Assisted Selection in Crop BreedingPawan Chauhan
Marker Assisted Selection is a value addition to conventional methods of Crop Breeding. It has been gaining importance in plant breeding with new generation of plant breeders and to get accurate and fast desired result from plant breeding.
Multiple inbred founder lines are inter-mated for several generations prior to creating inbred lines, resulting in a diverse population whose genomes are fine scale mosaics of contributions from all founders.
This document discusses wide hybridization or distant hybridization in maize. It begins by defining hybridization and distant hybridization. It then discusses the history of important wide crosses done in crops. Some key points made include:
- Thomas Fairchild produced the first wide cross between carnation and sweet william in 1717.
- Karpechenko produced the intergeneric hybrid Raphanobrassica in 1928.
- Rimpu produced the first intergeneric hybrid triticale in 1890, which had greater potential than Raphanobrassica.
- Problems with wide crosses include cross incompatibility, hybrid inviability, hybrid sterility, and hybrid breakdown.
- Wild relatives of maize like
This document discusses distant hybridization, which involves crossing individuals from different plant species or genera. Some key points:
- The first recorded distant hybrid was between carnation and sweet william produced in 1717. An inter-generic hybrid called raphanobrassica was produced in 1928.
- Problems with distant hybrids include cross incompatibility, hybrid inviability, sterility, and breakdown in subsequent generations. Techniques like embryo rescue can help overcome some issues.
- Distant hybridization can be used to transfer beneficial traits like disease resistance between species. It has led to improvements in crops through hybrid varieties with increased yield, adaptation, and resistance to insects and disease.
This document discusses the concept of heterosis, also known as hybrid vigor. It defines heterosis as the superiority of F1 hybrids over their parents in traits like yield, vigor and adaptation. The document then discusses the history of heterosis research and different hypotheses for the genetic basis of heterosis, including dominance, overdominance and epistasis. It also covers types of heterosis estimates and how heterosis is manifested. Factors affecting heterosis and various methods for heterosis breeding in crops are outlined.
1) Synthetic and composite varieties are developed in cross-pollinated crops by mixing seeds from multiple parental lines and allowing open-pollination.
2) Synthetic varieties are produced by evaluating parental lines for general combining ability and mixing seeds in a controlled manner, while composite varieties simply mix seeds without evaluating parental lines.
3) Both synthetic and composite varieties allow farmers to use saved seed for a few years and are maintained by open-pollination, providing more yield stability than hybrids.
This document discusses the development of inbred lines through repeated self-pollination and selection over multiple generations. It describes how inbred lines are developed from variable source populations in both self- and cross-pollinated crops using methods like pedigree selection. Inbred lines are homozygous genotypes that are then used to produce hybrid varieties which benefit from heterosis or hybrid vigor. The document outlines the procedures for inbred line development and some of the early hybrid varieties released for important crops in India.
The document discusses three methods for selecting pure lines from crosses in self-pollinated crops: pedigree method, bulk method, and single seed descent method.
The pedigree method involves selecting individual plants from segregating generations and tracking their offspring through generations until homozygosity is achieved. The bulk method involves growing segregating generations in bulk until homozygosity, then selecting individuals. The single seed descent method rapidly advances generations by growing only one seed per plant in each generation to achieve a random sample of homozygous lines.
Marker Assisted Selection in Crop BreedingPawan Chauhan
Marker Assisted Selection is a value addition to conventional methods of Crop Breeding. It has been gaining importance in plant breeding with new generation of plant breeders and to get accurate and fast desired result from plant breeding.
Multiple inbred founder lines are inter-mated for several generations prior to creating inbred lines, resulting in a diverse population whose genomes are fine scale mosaics of contributions from all founders.
This document discusses wide hybridization or distant hybridization in maize. It begins by defining hybridization and distant hybridization. It then discusses the history of important wide crosses done in crops. Some key points made include:
- Thomas Fairchild produced the first wide cross between carnation and sweet william in 1717.
- Karpechenko produced the intergeneric hybrid Raphanobrassica in 1928.
- Rimpu produced the first intergeneric hybrid triticale in 1890, which had greater potential than Raphanobrassica.
- Problems with wide crosses include cross incompatibility, hybrid inviability, hybrid sterility, and hybrid breakdown.
- Wild relatives of maize like
This document discusses distant hybridization, which involves crossing individuals from different plant species or genera. Some key points:
- The first recorded distant hybrid was between carnation and sweet william produced in 1717. An inter-generic hybrid called raphanobrassica was produced in 1928.
- Problems with distant hybrids include cross incompatibility, hybrid inviability, sterility, and breakdown in subsequent generations. Techniques like embryo rescue can help overcome some issues.
- Distant hybridization can be used to transfer beneficial traits like disease resistance between species. It has led to improvements in crops through hybrid varieties with increased yield, adaptation, and resistance to insects and disease.
This document discusses the concept of heterosis, also known as hybrid vigor. It defines heterosis as the superiority of F1 hybrids over their parents in traits like yield, vigor and adaptation. The document then discusses the history of heterosis research and different hypotheses for the genetic basis of heterosis, including dominance, overdominance and epistasis. It also covers types of heterosis estimates and how heterosis is manifested. Factors affecting heterosis and various methods for heterosis breeding in crops are outlined.
Breeding techniques in self pollinated crops presentationDev Hingra
1. Plant breeding techniques for self-pollinated crops include plant introduction, pure line selection, mass selection, pedigree method, bulk method, backcross method, and mutation breeding.
2. Pure line selection involves selecting individual plants, evaluating their progeny, and conducting yield trials to develop uniform varieties. Mass selection composites seed from selected plants for future planting.
3. Plant introduction is an oldest method that can introduce entirely new crop species or superior varieties from other regions. It provides germplasm for breeding programs.
This document discusses different types of mapping populations that can be used for genetic mapping and molecular breeding programs. It describes F2, F2:F3, backcross, doubled haploid (DH), recombinant inbred line (RIL), and near-isogenic line (NIL) populations. For each type, it provides details on how they are developed, their characteristics, and merits and demerits relative to mapping objectives. The document emphasizes that the choice of mapping population depends on the research goals, availability of markers, and existing molecular maps. RILs and DHs allow for replication over environments but require more time and resources to develop.
This document discusses marker-assisted backcrossing (MAB) for introgressing traits from a donor parent into a recipient line. MAB uses DNA markers linked to target genes/QTLs to aid in selection. Markers can be used for foreground selection of target genes, background selection to recover the recipient genome, and recombinant selection to minimize linkage drag. A case study is described where MAB was used over multiple generations to introgress 5 drought resistance QTLs from a donor rice variety into a recipient variety. Through foreground, background, and recombinant selection using DNA markers, lines were developed with the target QTLs and most of the recipient genetic background.
This document discusses speed breeding, a technique to accelerate crop breeding cycles. Traditional breeding can take many years to develop new varieties while meeting future food demands poses challenges. Speed breeding uses controlled environmental conditions like extended photoperiod and supplemental lighting to complete multiple generations in a year. Case studies show this approach led wheat and barley to flower in half the time and generated 5 soybean generations per year. Speed breeding holds potential to rapidly develop climate-resilient varieties on a smaller scale while combining with genomics and other innovations.
Heterotic group “is a group of related or unrelated genotypes from the same or different populations, which display similar combining ability and heterotic response when crossed with genotypes from other genetically distinct germplasm groups.”
This document summarizes research on advances in plant breeding systems. It discusses how modern tools like molecular markers, marker-assisted selection, genomic selection, and new statistical methods are being used along with technologies like RNA interference, CRISPR/Cas9, and TALENs to introduce beneficial genes and improve traits. Specific examples discussed include research on improving okra and rice varieties for traits like disease resistance and yield through techniques like tissue culture, molecular characterization, and genome editing. The document also summarizes research on inducing mutations in wheat using chemicals like EMS to generate genetic variability for breeding programs.
This document provides information on breeding methods for self-pollinated crops. It discusses pureline selection and mass selection methods. Pureline selection involves isolating pure lines from a mixed population and selecting the best ones. Mass selection selects desirable plants from a mixed population based on phenotype. The document compares pureline and mass selection, noting that pureline selection results in more uniform cultivars while mass selection cultivars are heterogeneous mixtures. It also describes multiline breeding, which develops cultivars that are mixtures of isolines or related lines to provide genetic diversity and disease resistance.
Recurrent selection is a plant breeding technique that involves repeated cycles of selection and intermating to improve quantitative traits in a population. There are several types including simple recurrent selection, recurrent selection for general combining ability, and recurrent selection for specific combining ability. Recurrent selection for specific combining ability uses homozygous testers to select for specific combining ability through multiple generations of testing cross performances, selecting best performers, and intermating selections. This allows for systematic accumulation of favorable alleles while maintaining genetic variation to continue making progress from selection.
Marker-assisted selection (MAS) is a plant breeding method that uses DNA markers to select for desirable traits. It allows breeders to select plants earlier in development compared to phenotypic selection. MAS has advantages like being unaffected by environment and ability to select for recessive traits, but may be more expensive initially than conventional methods. Careful analysis of costs and benefits is needed to determine if MAS is advantageous for a particular program over traditional breeding. MAS requires tightly linked markers, knowledge of marker-trait associations, and data management to be effective. A variety of MAS approaches exist like backcrossing, pyramiding, and combined MAS and phenotypic selection.
Gene introgression from wild relatives to cultivated plantsManjappa Ganiger
This document summarizes a seminar on using crop wild relatives to introduce beneficial genes into cultivated crops. It discusses how crop wild relatives contain genetic diversity that can provide traits like pest and disease resistance, abiotic stress tolerance, and improved yields. Specific examples are given of introducing disease resistance genes from wild relatives into tomatoes and rust resistance genes into wheat. The use of wild rice species to develop rice varieties with improved resistance to various diseases and insects is also described.
Selection: pure line, mass and pedigree breeding methods for self pollinated ...Vinod Pawar
This document discusses different selection methods used in self-pollinating crops, including pure line selection, mass selection, and pedigree selection. Pure line selection involves selecting the best individual plants and propagating their progeny to create homogeneous varieties. Mass selection selects many plants with desirable traits and mixes their seeds to create heterogeneous varieties with wider adaptation. Pedigree selection maintains records of each selected plant's ancestry over multiple generations to develop homogeneous, homozygous varieties taking 14-15 years.
This document discusses different types of male sterility in plants, including genetic male sterility (GMS), cytoplasmic male sterility (CMS), and chemically-induced male sterility (CHA). It describes how each type of male sterility works and how it can be used for hybrid seed production. Specifically, CMS uses cytoplasmic genes to induce sterility and requires maintainer and restorer lines, while GMS uses nuclear genes and can be environmentally sensitive. The document also covers transgenic systems like Barnase/Barstar and provides examples of major crops where male sterility systems have been applied.
Pure Line Theory and Pure line SelectionNikhilNik25
- Johannsen developed the pure line theory while working with princess beans in 1901. He established 19 pure lines through individual plant selection and followed with selection among the pure lines.
- Johannsen concluded that continuous inbreeding leads to homozygosity, variation within a pure line is due to environment only, and selection within a pure line is not effective because all plants have the same genotype.
- A pure line is the progeny of a single homozygous, self-pollinated plant. Pure line selection involves evaluating individual plant progeny from a self-pollinated crop to release the best as a pure line variety.
This document discusses gene pyramiding as a tool for developing durable resistance in crops. It defines gene pyramiding as combining two or more genes from multiple parents to develop elite lines with simultaneous expression of multiple genes. The objectives of gene pyramiding are to enhance traits, meet deficits in elite cultivars, and increase durability. Types of gene pyramiding include conventional pedigree breeding and backcrossing as well as molecular marker-assisted selection and transgenic methods. Gene pyramiding provides advantages like wider disease resistance and improved elite cultivars, while limitations include difficulty achieving multiple gene incorporation. Examples and applications in rice, wheat and other crops are also provided.
Reverse breeding is a novel plant breeding technique that allows the development of parental lines directly from any superior heterozygous plant. It involves suppressing meiotic recombination to produce gametes with whole parental chromosome sets, followed by doubling of haploids to generate parental lines. Two case studies demonstrate using RNAi to silence meiotic genes in Arabidopsis thaliana, producing parental lines that reconstitute the original hybrid when crossed. A second technique, marker-assisted reverse breeding, uses high-density SNP genotyping instead of gene silencing to select maize lines similar to original parents within one year. Reverse breeding techniques accelerate breeding and facilitate hybrid improvement without prior knowledge of parental lines.
The document discusses MAGIC (Multi-parent Advanced Generation Inter-Cross) populations, which are created by intercrossing multiple parent lines over several generations. This increases recombination and genetic diversity. Key points:
- MAGIC populations allow more precise mapping of QTLs controlling quantitative traits compared to biparental populations.
- Two case studies describe the development of MAGIC populations in rice with 8 founders each, and tomato with 8 founders. Traits like yield, disease resistance, and abiotic stress tolerance were evaluated.
- Advantages include exploiting more genetic variation, developing varieties with favorable trait combinations, and more accurate gene mapping. Limitations include requiring more time, resources for phenotyping and breeding.
This document discusses the diallel selective mating approach (DSM) for genetic improvement of autogamous crops. DSM involves three steps: 1) a parental diallel series of crosses between multiple parents, 2) F1 diallel series of crosses between F1 plants, and 3) selective mating series where selected F2 plants are intercrossed and selfed in successive generations. The goal is to accumulate desirable genes and increase recombination through restoring heterozygosity via intermating selected plants over multiple cycles. While it broadens the genetic base, DSM is more complex than pedigree methods and success depends on identifying desirable plants in segregating generations.
This document provides information on various plant breeding methods. It discusses the production of new crop varieties through selection, introduction, hybridization, ploidy, mutation, and tissue culture. Popular plant breeders like M.S. Swaminathan and Venkataramanan are mentioned. Introduction of plants from their native places to new locations for crop improvement is described. Breeding methods like inbreeding, outbreeding, and heterosis are explained. The theories of heterosis like dominance hypothesis and overdominance hypothesis are presented. The document highlights the effects and advantages of hybrid vigor in crops.
This document discusses a student project on plant breeding tomatoes. It will involve growing tomatoes from two varieties, Marimar and Diamante, in controlled and experimental groups. The project aims to develop a new high-yielding tomato variety or observe differences in fruit yield between the groups. The document outlines the project activities, which include preparing planting materials and soil, planting the tomato seeds, and observing and caring for the young plants. It is hoped that the project will help address issues of malnutrition, food shortage, and poverty through improving tomato yields.
Breeding techniques in self pollinated crops presentationDev Hingra
1. Plant breeding techniques for self-pollinated crops include plant introduction, pure line selection, mass selection, pedigree method, bulk method, backcross method, and mutation breeding.
2. Pure line selection involves selecting individual plants, evaluating their progeny, and conducting yield trials to develop uniform varieties. Mass selection composites seed from selected plants for future planting.
3. Plant introduction is an oldest method that can introduce entirely new crop species or superior varieties from other regions. It provides germplasm for breeding programs.
This document discusses different types of mapping populations that can be used for genetic mapping and molecular breeding programs. It describes F2, F2:F3, backcross, doubled haploid (DH), recombinant inbred line (RIL), and near-isogenic line (NIL) populations. For each type, it provides details on how they are developed, their characteristics, and merits and demerits relative to mapping objectives. The document emphasizes that the choice of mapping population depends on the research goals, availability of markers, and existing molecular maps. RILs and DHs allow for replication over environments but require more time and resources to develop.
This document discusses marker-assisted backcrossing (MAB) for introgressing traits from a donor parent into a recipient line. MAB uses DNA markers linked to target genes/QTLs to aid in selection. Markers can be used for foreground selection of target genes, background selection to recover the recipient genome, and recombinant selection to minimize linkage drag. A case study is described where MAB was used over multiple generations to introgress 5 drought resistance QTLs from a donor rice variety into a recipient variety. Through foreground, background, and recombinant selection using DNA markers, lines were developed with the target QTLs and most of the recipient genetic background.
This document discusses speed breeding, a technique to accelerate crop breeding cycles. Traditional breeding can take many years to develop new varieties while meeting future food demands poses challenges. Speed breeding uses controlled environmental conditions like extended photoperiod and supplemental lighting to complete multiple generations in a year. Case studies show this approach led wheat and barley to flower in half the time and generated 5 soybean generations per year. Speed breeding holds potential to rapidly develop climate-resilient varieties on a smaller scale while combining with genomics and other innovations.
Heterotic group “is a group of related or unrelated genotypes from the same or different populations, which display similar combining ability and heterotic response when crossed with genotypes from other genetically distinct germplasm groups.”
This document summarizes research on advances in plant breeding systems. It discusses how modern tools like molecular markers, marker-assisted selection, genomic selection, and new statistical methods are being used along with technologies like RNA interference, CRISPR/Cas9, and TALENs to introduce beneficial genes and improve traits. Specific examples discussed include research on improving okra and rice varieties for traits like disease resistance and yield through techniques like tissue culture, molecular characterization, and genome editing. The document also summarizes research on inducing mutations in wheat using chemicals like EMS to generate genetic variability for breeding programs.
This document provides information on breeding methods for self-pollinated crops. It discusses pureline selection and mass selection methods. Pureline selection involves isolating pure lines from a mixed population and selecting the best ones. Mass selection selects desirable plants from a mixed population based on phenotype. The document compares pureline and mass selection, noting that pureline selection results in more uniform cultivars while mass selection cultivars are heterogeneous mixtures. It also describes multiline breeding, which develops cultivars that are mixtures of isolines or related lines to provide genetic diversity and disease resistance.
Recurrent selection is a plant breeding technique that involves repeated cycles of selection and intermating to improve quantitative traits in a population. There are several types including simple recurrent selection, recurrent selection for general combining ability, and recurrent selection for specific combining ability. Recurrent selection for specific combining ability uses homozygous testers to select for specific combining ability through multiple generations of testing cross performances, selecting best performers, and intermating selections. This allows for systematic accumulation of favorable alleles while maintaining genetic variation to continue making progress from selection.
Marker-assisted selection (MAS) is a plant breeding method that uses DNA markers to select for desirable traits. It allows breeders to select plants earlier in development compared to phenotypic selection. MAS has advantages like being unaffected by environment and ability to select for recessive traits, but may be more expensive initially than conventional methods. Careful analysis of costs and benefits is needed to determine if MAS is advantageous for a particular program over traditional breeding. MAS requires tightly linked markers, knowledge of marker-trait associations, and data management to be effective. A variety of MAS approaches exist like backcrossing, pyramiding, and combined MAS and phenotypic selection.
Gene introgression from wild relatives to cultivated plantsManjappa Ganiger
This document summarizes a seminar on using crop wild relatives to introduce beneficial genes into cultivated crops. It discusses how crop wild relatives contain genetic diversity that can provide traits like pest and disease resistance, abiotic stress tolerance, and improved yields. Specific examples are given of introducing disease resistance genes from wild relatives into tomatoes and rust resistance genes into wheat. The use of wild rice species to develop rice varieties with improved resistance to various diseases and insects is also described.
Selection: pure line, mass and pedigree breeding methods for self pollinated ...Vinod Pawar
This document discusses different selection methods used in self-pollinating crops, including pure line selection, mass selection, and pedigree selection. Pure line selection involves selecting the best individual plants and propagating their progeny to create homogeneous varieties. Mass selection selects many plants with desirable traits and mixes their seeds to create heterogeneous varieties with wider adaptation. Pedigree selection maintains records of each selected plant's ancestry over multiple generations to develop homogeneous, homozygous varieties taking 14-15 years.
This document discusses different types of male sterility in plants, including genetic male sterility (GMS), cytoplasmic male sterility (CMS), and chemically-induced male sterility (CHA). It describes how each type of male sterility works and how it can be used for hybrid seed production. Specifically, CMS uses cytoplasmic genes to induce sterility and requires maintainer and restorer lines, while GMS uses nuclear genes and can be environmentally sensitive. The document also covers transgenic systems like Barnase/Barstar and provides examples of major crops where male sterility systems have been applied.
Pure Line Theory and Pure line SelectionNikhilNik25
- Johannsen developed the pure line theory while working with princess beans in 1901. He established 19 pure lines through individual plant selection and followed with selection among the pure lines.
- Johannsen concluded that continuous inbreeding leads to homozygosity, variation within a pure line is due to environment only, and selection within a pure line is not effective because all plants have the same genotype.
- A pure line is the progeny of a single homozygous, self-pollinated plant. Pure line selection involves evaluating individual plant progeny from a self-pollinated crop to release the best as a pure line variety.
This document discusses gene pyramiding as a tool for developing durable resistance in crops. It defines gene pyramiding as combining two or more genes from multiple parents to develop elite lines with simultaneous expression of multiple genes. The objectives of gene pyramiding are to enhance traits, meet deficits in elite cultivars, and increase durability. Types of gene pyramiding include conventional pedigree breeding and backcrossing as well as molecular marker-assisted selection and transgenic methods. Gene pyramiding provides advantages like wider disease resistance and improved elite cultivars, while limitations include difficulty achieving multiple gene incorporation. Examples and applications in rice, wheat and other crops are also provided.
Reverse breeding is a novel plant breeding technique that allows the development of parental lines directly from any superior heterozygous plant. It involves suppressing meiotic recombination to produce gametes with whole parental chromosome sets, followed by doubling of haploids to generate parental lines. Two case studies demonstrate using RNAi to silence meiotic genes in Arabidopsis thaliana, producing parental lines that reconstitute the original hybrid when crossed. A second technique, marker-assisted reverse breeding, uses high-density SNP genotyping instead of gene silencing to select maize lines similar to original parents within one year. Reverse breeding techniques accelerate breeding and facilitate hybrid improvement without prior knowledge of parental lines.
The document discusses MAGIC (Multi-parent Advanced Generation Inter-Cross) populations, which are created by intercrossing multiple parent lines over several generations. This increases recombination and genetic diversity. Key points:
- MAGIC populations allow more precise mapping of QTLs controlling quantitative traits compared to biparental populations.
- Two case studies describe the development of MAGIC populations in rice with 8 founders each, and tomato with 8 founders. Traits like yield, disease resistance, and abiotic stress tolerance were evaluated.
- Advantages include exploiting more genetic variation, developing varieties with favorable trait combinations, and more accurate gene mapping. Limitations include requiring more time, resources for phenotyping and breeding.
This document discusses the diallel selective mating approach (DSM) for genetic improvement of autogamous crops. DSM involves three steps: 1) a parental diallel series of crosses between multiple parents, 2) F1 diallel series of crosses between F1 plants, and 3) selective mating series where selected F2 plants are intercrossed and selfed in successive generations. The goal is to accumulate desirable genes and increase recombination through restoring heterozygosity via intermating selected plants over multiple cycles. While it broadens the genetic base, DSM is more complex than pedigree methods and success depends on identifying desirable plants in segregating generations.
This document provides information on various plant breeding methods. It discusses the production of new crop varieties through selection, introduction, hybridization, ploidy, mutation, and tissue culture. Popular plant breeders like M.S. Swaminathan and Venkataramanan are mentioned. Introduction of plants from their native places to new locations for crop improvement is described. Breeding methods like inbreeding, outbreeding, and heterosis are explained. The theories of heterosis like dominance hypothesis and overdominance hypothesis are presented. The document highlights the effects and advantages of hybrid vigor in crops.
This document discusses a student project on plant breeding tomatoes. It will involve growing tomatoes from two varieties, Marimar and Diamante, in controlled and experimental groups. The project aims to develop a new high-yielding tomato variety or observe differences in fruit yield between the groups. The document outlines the project activities, which include preparing planting materials and soil, planting the tomato seeds, and observing and caring for the young plants. It is hoped that the project will help address issues of malnutrition, food shortage, and poverty through improving tomato yields.
plant breeding techniques used in self-pollinated plants v/s those used in cr...Anusha Babooa
1. Plant breeding techniques differ between self-pollinated and cross-pollinated plants. Common techniques for self-pollinated plants include mass selection, pure line selection, pedigree selection, and backcross breeding. Hybridization is more common for cross-pollinated plants.
2. Selection, hybridization, and introduction are used for both types of plants. Rare techniques include mutation breeding and polyploidy.
3. Recurrent selection, synthetic varieties, and multiline varieties are mainly used to improve cross-pollinated crops where pollination control is difficult.
Breeding methods in cross pollinated cropsDev Hingra
This document discusses methods of breeding in cross-pollinated crops. It describes mass selection, progeny selection (ear-to-row method), modified ear-to-row method, and recurrent selection. It also discusses hybrid varieties, synthetic varieties, and the operations involved in producing hybrids and synthetics. The key methods discussed are mass selection, ear-to-row selection, and recurrent selection.
Breeding involves applying genetic principles to improve economically important traits in domestic animals. The goal is to produce individuals with superior traits and characteristics, and to develop new traits. Common breeding methods include hand mating, pair mating, and harem mating. Inbreeding involves mating closely related individuals over several generations to develop lines for commercial use. It increases homozygosity but also risks inbreeding depression. Outbreeding introduces new genes by mating distantly related animals. Crossbreeding and backcrossing are used to combine desirable traits from different breeds. Grading up and mutations can also be used to improve animal stock over generations.
Plant breeding, its objective and historical development- pre and post mendel...Avinash Kumar
ppt for 1st chapter of plant breeding. it includes defination & objectives of plant breeding, role & challanges of plant breeeders and historical development
This document evaluates plant breeding techniques for their compatibility with organic agriculture. It begins by explaining that seeds are the basis of agricultural production but most organic farmers know little about how their seedstocks have been produced. It then provides an overview of standard plant breeding and multiplication techniques, distinguishing those that act at the plant, cell, and DNA levels. The aim is to inform ongoing discussions around organic plant breeding by explaining each technique and assessing its suitability according to organic principles.
MLN Workshop: Breeding for maize lethal necrosis -- B DasCIMMYT
CIMMYT's maize breeding program focuses on developing varieties tolerant to biotic and abiotic stresses for tropical regions where maize is an important food crop. The program has screened over 45,000 varieties for tolerance to Maize Lethal Necrosis (MLN), finding that around 10% show some tolerance. Promising tolerant inbred lines and hybrids have been identified and some recommended for release. CIMMYT is expanding its MLN screening capacity through additional sites in East Africa that experience natural MLN infection. The goal is to accelerate the development and release of MLN-tolerant varieties to address the devastating impacts of the disease.
This document discusses mutation breeding and mutation induction. It defines mutation as a heritable change in phenotype and describes two types of mutations: those caused by changes in nuclear DNA and those caused by changes in cytoplasmic DNA. It then outlines the history of mutation research and induction starting in the 1920s. The document discusses spontaneous versus induced mutations and different mutagens used to induce mutations like radiation, chemicals, and base analogues. It describes the breeding procedure for mutation breeding and screening techniques. Finally, it covers advantages, limitations, research centers involved, and some achievements of mutation breeding.
This document discusses plant biotechnology techniques used to genetically modify organisms. It defines biotechnology as applying technology to modify biological organisms by adding genes from other species. The key techniques discussed are identifying genes from other organisms that control desired traits and introducing those genes into plants through transformation. This allows developing crops with improved traits like herbicide or insect resistance, drought tolerance, or increased nutritional content. The document outlines the process of gene cloning, creation of transformation cassettes containing the gene of interest and selectable marker, and delivery into plants via Agrobacterium or gene gun. Extensive testing of transgenic plants in the lab and field is needed before commercial release to ensure safety and trait expression.
Chickpea breeding aims to develop higher yielding varieties with improved resistance to biotic and abiotic stresses. Breeding methods include hybridization of selected parents followed by selection of progeny. Hybridization techniques can increase success rates. Segregating populations are handled using pedigree, bulk, or single seed descent selection. Mutation breeding induces genetic variation which is selected in subsequent generations. This helps develop stress resistant and high yielding varieties adapted to Pakistan.
This document discusses domestication, polyploidy, and genomics of crops and weeds. It notes that most major crop species were domesticated around 10,000 years ago, with a few more recently. Polyploidy, or whole genome duplication events, have also played an important role in crop evolution. The document examines genome sizes and components of various crop species, and notes that repetitive elements like transposons can make up large proportions of plant genomes. Differences in repetitive sequences between microspecies of dandelion are also discussed.
Comparative genomic analysis in Zingiberales: what can we learn from banana to enable Ensete and Boesenbergia to reach their potential?
Talk for Plant and Animal Genomics XXV 25 - San Diego January 2017
Trude Schwarzacher, Jennifer A. Harikrishna and Pat Heslop-Harrison, University of Leicester and University of Malaya
phh(a)molcyt.com
Within the Zingiberales there are many orphan crops that are grown in Africa and Asia where recently started genomic efforts will have an impact for the future understanding and breeding of these crops. Advanced genomics and genome knowledge of the taxonomically closely related genus Musa will help identify genes and their function. We will discuss relevant recent work with Musa and results from DNA sequencing, examinations of diversity and studies of genome structure, gene expression and epigenetic control in Boesenbergia and ensete. Ensete is an important starch staple food in Ethiopia. It is harvested just as the monocarpic plant starts to flower, a few years after planting, and the stored starch extracted from the pseudo-stem and corm. A genome sequence has been published, but there is little genomics. Characterization of the diversity in the species and understanding of the differences to Musa will enable selection and breeding for crop improvement to meet the requirements of increasing populations, climate change and environmental sustainability. Boesenbergia rotunda is widely used in traditional medicine in Asia and has been shown to produce secondary metabolites with antiviral activity. For high throughput propagation and metabolite production in vitro culture is employed; embryogenic calli of B. rotunda in vitro are able to regenerate into plants but lose this ability after prolonged periods in cell suspension media. Epigenetic factors, including histone modifications and DNA methylation are likely to play crucial roles in the regulation of genes involved in totipotency and plant regeneration. These findings are also relevant to other crops within the Zingiberales. Further details will be given at www.molcyt.com
Hybridization is the process of breeding plants and animals to produce hybrid offspring that have desired qualities. It involves cross-breeding two parent varieties to develop a new hybrid variety that possesses traits from both parents, such as high yield, disease resistance, or climate tolerance. The process involves selecting parent plants, removing stamens from female flowers, collecting pollen from male flowers, pollinating the female flowers, collecting mature seeds, and selecting offspring with better qualities over several generations. Hybrid varieties developed through this process contribute greatly to agricultural progress as they are widely used for traits like high yield and disease resistance.
1. The document discusses components of variation, heritability, types of heritability, genetic advance, environment, and genotype-environment interaction. It defines key terms like phenotypic variation, genotypic variation, broad sense heritability, narrow sense heritability, genetic advance, and genotype-environment interaction.
2. Heritability is the ratio of genotypic variance to phenotypic variance and indicates the proportion of a phenotypic trait caused by genetic factors. Broad sense heritability includes all genetic effects while narrow sense only includes additive genetic effects.
3. Genetic advance measures the expected genetic improvement from selection and depends on genetic variability, heritability, and selection intensity. High genetic advance indicates a trait is
Organic peanut production relies on cultural techniques that maintain soil fertility through crop rotation and composting, rather than off-farm inputs. While labor and management costs are higher for organic peanuts, farmers can find higher demand and premium prices in organic markets. The document discusses organic peanut production methods, varieties suited to different regions, challenges in organic marketing, and potential alternative uses for organic peanuts including forage and biodiesel production.
1) Quantitative genetics focuses on inheritance of quantitative traits controlled by multiple genes and influenced by the environment.
2) A basic single-gene model is used to explain quantitative genetic theory, including calculations of population mean, genetic effects, and variance components.
3) More complex multi-gene models and analyses like ANOVA and heritability are then introduced to better capture quantitative traits controlled by numerous genes and environmental influences.
The document outlines the materials and steps needed to perform hybridization in lab conditions using sweet pea flowers of different varieties. The key steps are: 1) emasculating female flowers by removing their anthers, 2) collecting pollen from male flowers by crushing their anthers, and 3) dusting the collected pollen onto the stigma of the emasculated female flowers. The hybridized flowers are then covered with paper bags to avoid contamination from external pollen sources.
This presentation discusses hybridization techniques in rice. It begins with definitions of key terms like hybrid and homozygous. It describes the objectives of hybridization like increasing yield and developing disease resistance. The materials, floral biology, and step-by-step process of emasculation and pollination are explained. Maintaining genetic diversity through hybridization is important for crop health. Hybrid rice often displays heterosis or hybrid vigor, increasing yields. The Green Revolution widely used hybridization to create high-yielding rice varieties adapted to local conditions.
This document describes a biology project on plant breeding prepared by a student for their class XII exams. It provides an overview of advanced plant breeding techniques, focusing on marker-assisted selection (MAS). MAS uses DNA markers linked to desirable genes to select plants without evaluating the trait directly. The techniques allows for faster selection and stacking of multiple resistance genes to develop durable crop resistance. MAS is particularly useful for traits that are difficult, time-consuming, or expensive to evaluate through conventional methods.
Process whereby a marker is used for indirect selection of a genetic determinant or determinants of a trait of interest (i.e. productivity, disease resistance, abiotic stress tolerance, and/or quality).
Trait of interest is selected not based on the trait itself but on a marker linked to it.
The assumption is that linked allele associates with the gene and/or quantitative trait locus (QTL) of interest. MAS can be useful for traits that are difficult to measure, exhibit low heritability, and/or are expressed late in development.
Pre-Requisites: Two pre-requisites for marker assisted selection are: (i) a tight linkage between molecular marker and gene of interest, and (ii) high heritability of the gene of interest.
Markers Used: The most commonly used molecular markers include amplified fragment length polymorphisms (AFLP), restriction fragment length polymorphisms (RFLP), random amplified polymorphic DNA (RAPD), simple sequence repeats (SSR) or micro satellites, single nucleotide polymorphisms (SNP), etc. The use of molecular markers differs from species to species also.
Marker assisted selection or marker aided selection is an indirect selection process where a trait of interest is selected based on a marker linked to a trait of interest, rather than on the trait itself. This process has been extensively researched and proposed for plant and animal breeding.Marker-assisted breeding uses DNA markers associated with desirable traits to select a plant or animal for inclusion in a breeding program early in its development. ... This genetic test is helping breeders to select for hornless cattle, which makes it safer for the animals themselves and the people handling them.
Marker-assisted selection (MAS) uses molecular markers linked to genes or traits of interest to select desirable plants. MAS can reduce the time needed for variety development compared to conventional breeding by allowing early generation selection. The success of MAS depends on the close linkage between markers and target genes. MAS has been used successfully in crops like rice, maize, and chickpeas to develop varieties with improved disease resistance and other traits. While powerful, MAS also has limitations like the need for accurate marker-trait linkage and potential recombination between markers and genes.
Genomic aided selection for crop improvementtanvic2
This document summarizes a case study on the draft genome sequence of chickpea. Key points include:
- Researchers sequenced and assembled the ~738Mb genome of a kabuli chickpea variety, identifying an estimated 28,269 genes.
- The genome provides resources for molecular breeding through identification of candidate genes for traits like disease resistance.
- Resequencing of elite varieties provided insights into genome diversity and domestication.
- Analysis found the draft captured over 90% of the gene space through mapping of transcriptome data, and contained homologs for over 98% of core eukaryotic genes.
Marker assisted selection is the breeding strategy in which selection for a gene is based on molecular markers closely linked to the gene of interest rather than the gene itself, and the markers are used to monitor the incorporation of the desirable allele from the donor source. Selection of a genotype carrying desirable gene via linked marker (s) is called Marker Assisted Selection. MAS can be applied to possible to use this kind of information.
The prerequisites for the classical procedure of MAS are the tight linkage between molecular marker and gene of interest and high heritability of the gene of interest. It is noteworthy that the “quality” and the number of markers have a major impact on the success of MAS. The quality of markers relates to their characteristics and to the cost and the efficiency of the genotyping process. The number of markers affects the reliability of the linkage between them and the gene(s). In other words, screening a large number of markers has the potential to identify close and reliable linkage between the marker and the gene of interest. MAS has greater potential for efficient gene pyramiding combining several important genes in one cultivar. MAS is gaining considerable importance as it can improve the efficiency of plant breeding through precise transfer of genomic regions of interest and acceleration of the recovery of the recurrent parent genome. Marker-assisted selection is gaining considerable importance as it would improve the efficiency of plant breeding through precise transfer of genomic regions of interest (foreground selection) and accelerating the recovery of the recurrent parent genome (background selection). The use of MAS in crop improvement will not only reduce the cost of developing new varieties but will also increase the precision and efficiency of selection in the breeding program as well as lessen the number of years required to come up with a new crop variety.
This document discusses approaches for breeding wheat with resistance to rust diseases. It begins by noting the importance of wheat as a food crop and challenges in meeting future demand. Classical breeding approaches are described that involve determining breeding objectives, assessing genetic variation, crossing, evaluation and selection. Molecular approaches for identifying rust resistance genes using markers can detect variations directly and are not influenced by environment. An efficient breeding program requires clear objectives, understanding pathogen variation and available resistance sources to design programs. Selection of parents, hybridization techniques, bulk and pedigree selection methods, and marker assisted selection are described to introgress resistance while maintaining other important traits.
This document summarizes a study on marker assisted selection for disease resistance in legume crops. It discusses marker assisted selection (MAS) and its advantages over conventional breeding. MAS allows for indirect selection of traits using DNA markers linked to genes or traits of interest. It also describes specific examples of using MAS to develop disease resistance in pea and common bean crops by mapping genes conferring resistance to powdery mildew in pea and rust resistance in common bean. The studies aimed to validate DNA markers for use in MAS breeding programs to more efficiently develop legume varieties with improved disease resistance.
Application of molecular biology to conventional disease strategies ( M.Phil ...Satya Prakash Chaurasia
As resistance to disease in plants is genetically controlled, molecular tools like breeding resistant cultivars has been an intensively used approach for crop protection since near beginning of human civilization, the time when we did not know its molecular aspects. Even today, molecular biology is applied in multiple ways to control plant diseases. Some of which are breeding, tissue culture, marker assisted breeding, QTL- mapping, identification of novel resistance genes etc. With the commencement of advanced technologies in the recent past, we are now able to genetically modify a plant without wasting a lot of time and avoiding problems of sexual incompatibility which we encounter in breeding programs.
Marker assisted selection (MAS) is a technique used in animal breeding that uses genetic markers linked to traits of interest to indirectly select desirable individuals. MAS can improve traits more efficiently than traditional breeding by selecting early in an individual's life. The key advantages of MAS are that it allows selection based on traits that are difficult to measure, for recessive genes, and faster than phenotypic selection. Future challenges include reducing costs and developing methods for large-scale genotyping to implement MAS in large breeding populations.
Marker-Assisted Backcrossing in breedingbineeta123
Marker-assisted backcrossing can improve the efficiency of backcross breeding in three ways:
1) Markers can be used for early-generation selection when phenotyping traits is difficult.
2) Markers enable selection against the donor parent genome outside of the target region to minimize linkage drag.
3) Markers allow selection of rare recombinants near the target gene.
Using markers at multiple stages of selection, including for the target gene, recombinant selection around the gene, and background selection, can accelerate the recovery of the recurrent parent genome and potentially save 2-4 backcross generations.
Marker-assisted selection (MAS) uses DNA markers that are linked to genes or traits of interest to indirectly select for those traits. MAS can be integrated into traditional breeding programs. It allows for traits like disease resistance and quality to be selected for earlier in the breeding process compared to conventional phenotyping. MAS requires identifying tightly linked DNA markers, developing breeding populations to study marker segregation, isolating DNA, identifying polymorphisms, and correlating markers to traits. It has advantages like accuracy, speed, ability to select recessive alleles, and permit mapping of quantitative trait loci. Limitations include cost and difficulty associated with some marker techniques. For MAS of multiple traits, typically no more than 3-5 quantitative trait loci
Genetic markers, Classical markers, DNA markers, MICROSATELLITES, AFLP, SNP: Single Nucleotide Polymorphism, QTL: Quantitative Trait Locus, Activities of marker-assisted breeding, Marker-based breeding and conventional breeding Perspectives,The application of molecular technologies to plant breeding is still facing the following drawbacks and/or challenges
Pre-breeding involves introducing beneficial genes from exotic or wild plant materials into domestic crops to broaden their genetic base. It captures useful traits and puts them into forms usable for breeding programs. The document discusses pre-breeding strategies like backcrossing, convergent improvement, and bridge crosses. Pre-breeding has enhanced disease resistance and drought tolerance in crops like maize, pearl millet, and sorghum. While it provides long-term benefits, pre-breeding also faces challenges like linkage drag and hybrid sterility. Overall, pre-breeding is important for generating genetic diversity and new traits to develop improved crop varieties.
The document presents on gene stacking, pathway engineering, and marker-free transgenic development strategies. It discusses various methods for combining multiple genes/traits into plants, including gene stacking, gene pyramiding, sexual hybridization, re-transformation, co-transformation, and marker-free techniques. The goal is to develop crops with improved agronomic traits through plant genome engineering approaches.
Marker-assisted backcrossing (MAB) was used to introgress a submergence tolerance gene from donor variety IR49830 into the popular rice variety Swarna. MAB involved three levels of selection: foreground selection to select plants with the submergence tolerance gene, background selection to recover the Swarna genome, and recombinant selection to minimize the donor DNA in the background. Over multiple generations of backcrossing and selection, researchers were able to develop a version of Swarna with the submergence tolerance gene but that was otherwise genetically similar to the original Swarna variety.
Molecular Marker-assisted Breeding in RiceFOODCROPS
1. The document discusses molecular marker-assisted breeding in rice. It provides details on the expertise and experiences of Dr. Jian-Long Xu in molecular rice breeding including allele mining and marker-assisted selection.
2. Marker-assisted selection is described as a method to select phenotypes based on the genotype of linked markers rather than the target gene itself. The advantages of MAS include time and cost savings compared to traditional field trials.
3. Requirements for large-scale application of MAS include validation of QTL in breeding materials, efficient genotyping protocols, and decision support tools for breeders.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
The binding of cosmological structures by massless topological defectsSérgio Sacani
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field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
When I was asked to give a companion lecture in support of ‘The Philosophy of Science’ (https://shorturl.at/4pUXz) I decided not to walk through the detail of the many methodologies in order of use. Instead, I chose to employ a long standing, and ongoing, scientific development as an exemplar. And so, I chose the ever evolving story of Thermodynamics as a scientific investigation at its best.
Conducted over a period of >200 years, Thermodynamics R&D, and application, benefitted from the highest levels of professionalism, collaboration, and technical thoroughness. New layers of application, methodology, and practice were made possible by the progressive advance of technology. In turn, this has seen measurement and modelling accuracy continually improved at a micro and macro level.
Perhaps most importantly, Thermodynamics rapidly became a primary tool in the advance of applied science/engineering/technology, spanning micro-tech, to aerospace and cosmology. I can think of no better a story to illustrate the breadth of scientific methodologies and applications at their best.
Nucleophilic Addition of carbonyl compounds.pptxSSR02
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Large groups adjacent to the carbonyl will slow the rate of reaction.
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hematic appreciation test is a psychological assessment tool used to measure an individual's appreciation and understanding of specific themes or topics. This test helps to evaluate an individual's ability to connect different ideas and concepts within a given theme, as well as their overall comprehension and interpretation skills. The results of the test can provide valuable insights into an individual's cognitive abilities, creativity, and critical thinking skills
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Advance Plant Breeding Techniques
1. A Term paper on
ADVANCE PLANT BREEDING TECHNIQUES
Submitted To
Assoc. Professor Madhav Pandey Ph.D.,
Department of Genetics and Plant Breeding
Faculty of Agriculture
Agriculture and Forestry University
Rampur, Chitwan, Nepal
Submitted By
Khem Raj Pant
R-2014-PLB-06-M
M.Sc.Ag. (Plant Breeding), 1st
Semester
Agriculture and Forestry University
Rampur, Chitwan, Nepal
Principle of Plant Breeding II
April, 2015
2. 1. Introduction:
Traditional Plant Breeding procedures are based on manipulation of genes and
chromosomes through sexual reproduction in whole plants. The breeding procedures evolve from
the principle of Mendalian genetics. There has been significant improvement in production and
productivity of important cereal crops globally as a consequence of the “Green Revolution” and
other initiatives. However, today the stage has reached that the available traditional methods of
crop improvement are not sufficient to provide enough and staple food grains to the constantly
growing world population. This situation is projected to be worse by the year 2050 especially in
context of climate change. In other words, the conventional plant breeding practices may not able
to achieve the sustainability in today’s agriculture. Recent advances made in the area of
molecular biology and bioinformatics offer substantial opportunities for enhancing the
effectiveness of classical plant breeding programs. The following are the Advance plant breeding
techniques used in crop improvements:
2. MOLECULAR BREEDING (MARKER ASSISTED SELECTION, MAS)
The term ‘molecular breeding’ is used to describe plant breeding programmes that are supported
by the use of DNA-based markers. Marker assisted selection(MAS) is the breeding strategy in
which selection for a gene is based on molecular markers closely linked to the gene of interest
rather than the gene itself, and the markers are used to monitor the incorporation of the desirable
genes from the donor source. In this technique, linkages are sought between DNA markers and
agronomically important traits such as resistance to Pathogens, Insects and nematodes, tolerance
to abiotic stresses, quality parameters and quantitave traits. Instead for selection of the trait, the
breeder can select for a marker that can be detached very easily in the selection scheme. The
molecular breeding requires the following technologies; genetic maps, molecular marker linked
to agronomical traits, high throughput, automated diagnostic techniques and a modification in the
breeding practices. The essential requirements for marker assisted selection in a plant breeding
program are:
• Marker(s) should co-segregate or be closely linked (1cM or less is probably sufficient for
MAS) with the desired traits.
• An efficient means of screening large population for the molecular marker(s) should be
available. At present this means relatively easy analysis based on PCR technology.
• The screening technique should have high reproducibility across laboratories
• It should be economic to use and be user friendly.
Several strategies have been developed that allow on to screen a large number of random,
unmapped molecular markers in relatively short times and to select just those few markers that
resides in the vicinity of the target gene. These high volume marker technologies that have
shown efficacy are RAPD, AFLP, RFLP, Microsatellites, SNPS, etc. These methods rely on two
principles:
3. i. To generate hundreds or even thousands of potentially polymorphic DNA segments
and rapidly visualize from single preparation of DNA; and
ii. Use of Genetic stocks to identify among these thousands of DNA fragments, those
few derived from a region adjacent to the target genes.
In the past few years, by using one or more of these high volume marker technologies,
thousands of loci scattered throughout the have been assayed in a matter of weeks or months.
The next problem is to determine which of the amplified loci near the targeted gene. Two
strategies have proved effective:
1. Nearly isogenic line (NIL) strategy:
Breeders have developed NIL genetic stocks and have been maintaining these inbreds lines that
differ at the targeted locus. Nearly isogenic lines are created when a donor line (P1) is crossed
to a recipient line (P2). The resulting F1 hybrid is then back crossed to the P2 recipient to
produce the backcross 1 generation (BC1). From BC1, a single individual containing the
dominant alleles of the target genes from P1 is selected. Selection for the target gene is normally
made on the basis of phenotype. This BC1 individual is again backcrossed to P2, and the cycle of
backcross selection is repeated for a number of generations. In the BC7 generation, most if not
all of the genome wiil be derived from P2, except for a small chromosomal segment containing
the selected dominant allele, which is derived from P1. Line homozygous for the target gene can
be selected from the BC7F2 is said to be nearly isogenic with the recipient parent, P2.
2. Bulk segregent analysis (BSA): This method is more generally applicable, and relies on the
use of segregating populations (Michelmore et al., 1991). It requires the generation of
populations of bulked segregates (bulks). When P1 and P2 are hybridized, the F2 generation
derived from the cross will segregate for alleles from both parents at all loci throughout the
genome. If the F2 population is divided into two pools of contrasting individuals on the basis of
screenings at a single target locus, these two pools (Bulk 1 and Bulk 2) will differ in their allelic
content only at loci contained in the chromosomal region close to the target gene. Bulk 1
individuals selected for recessive phenotype will contains only P2 alleles near the target, while
Bulk 2 plants selected for dominants phenotypes will contains alleles from both P1 and P2 at loci
unlinked to the target.
Marker assisted selection has become a promising and potent approach for integrating
biotechnology with conventional and traditional breeding. The plant breeder interest on
molecular markers revolves around certain basic issues which have been illustrated below:
1. Resistance breeding: At present breeding for disease and pest resistance is conducted on the
segregating populations derived from crosses of susceptible cultivars with resistant donors.
These Populations are then selected either under natural disease or pest hot spots or under
artificially created conditions. Although these procedures have given excellent results, they are
time consuming. Besides, there are always susceptible plants that escape attack. Screening of
4. plants with several different pathogens and their pathotypes or pests and their biotypes
simultaneously or even sequentially is difficult, if not possible. Availability of tightly linked
genetic markers for resistance genes will help in identifying plants carrying these genes without
subjecting them to pathogen or insect attack in early generation. The breeder will require a low
amount of DNA from each individual plant to be tested without destroying the plants, and see the
presence or absence of the product of PCR reaction (marker band) on the gel. Only materials in
the advanced generations would be required to be tested in disease and insect nurseries. Thus,
with MAS it is now possible for the breeder to many rounds of selection in the year without
depending on the natural occurance of the pest or pathogen as well.
2. Pyramiding of major/minor genes into cultivars for development of durable
resistance/multiple resistance: Pathogens and insects are known to overcome resistance
provided by single genes. Single gene resistances are fragile and often broken down easily.
Therefore breeder intended to accumulate several major and minor resistance genes into one
cultivar in order to achieve durable resistance. Durability of resistance has been increased by
developing multiline and by pyramiding of resistance genes.MAS for resistance genes can be
useful in these approaches. Pyramiding of bacterial blight resistance genes Xa1, Xa2, Xa3,
Xa4, Xa5 and Xa10 in different combination using molecular markers has been reported in
rice (Yoshimura et al., 1995).
3. Improvement of qualitative character: RFLP markers have been linked to the linolenic
acid content Fan locus in soybean (Brummer et al., 1995). Not only this, RAPD markers that
control somatic embryogenesis in alfalfa have been identified (Yu and Pauls, 1993).
4. Molecular Markers for hybrid vigor: Hybrids in crops such as maize, sorghum, rice
pearl millet, cotton and several vegetable crops have contributed greatly towards increasing
the yield potential of these crops. Using the molecular marker on a set of diallel crosses
among eight elite parental lines widely used in Chinese hybrid rice production programme,
high correlation was found between specific heterozygosity and mid parent heterosis.
5. MAS for trait difficult to evaluate: The MAS is especially useful for the traits that are
ardous and/or expensive to evaluate such as male fertility restorer genes for cytoplasmic male
sterility in which the presence of the fertility restorer genes (Frs) in the breeding lines can’t
easily be detached by conventionally breeding technique as they involve careful and
extensive evaluation and analysis of innumerable segregants.
6. Molecular Marker and abiotic resistance: In rice and maize, QTL for root traits have
been identified and are being used to breed high yielding drought resistance Rice and Maize
genotypes. MAS have helped to improve the yield performance under drought in beans,
soybean and peas.
5. 3. Micro-Propagation:
Clonal Propagation in vitro is called Micro-propagation. The word clone was first used by
Webber for apply to cultivated plants that were propagated vegetatively. It signifies that plants
grown from such vegetative parts are not individuals in the ordinary sense, but are simply
transplanted parts of the same individual and such plants are identical. Thus, clonal propagation
is the multiplication of the genetically identical individuals by asexual reproduction while clone
is a plant population derived from a single individual by asexual individuals. The significant
advantage offered by the aseptic method of clonal propagation (Micropropagaion) over the
Conventional methods is that in a relatively short span of time and space, a large number of
plants can be produced starting from a single individuals. Some potential uses of clonal
propagation in agronomical crops are:
• Large scale increase of a heterozygous genotypes
• Increase of self incompatible genotypes
• Increase of a male sterile parent in a hybrid seed program
• Production of a disease free rootstock, and
• Preservation and international exchange of germplasm.
Advantages of Micropropagation:
In vitro micro-propagation techniques are now often preferred to conventional practices of
asexual propagation because of following advantages:
• A small amount of plant tissue is needed as the initial explant for regeneration of millions
of clonal plants in one year.
• The invitro stocks can be quickly proliferated at any time of the year.
• The invitro technique provides a method for speedly international exchange of plant
materials.
• Production of disease free plants.
• Germplasm storage: Plant breeding programme rely heavily on the germplasm.
Preservation of the germplasm is a mean to assure the availability of genetic materials as
the need arises.
• Seed Production: For Seed production in some of the crops, a major limiting factor is the
high degree of genetic conservation required. In such cases micropropagation can be
used.
6. 4. Double Haploid Production:
In the double haploid procedure, haploid plants are generated from anther of F1 plants, or by
other means, and the chromosomes of the haploid plants are doubled with colchicines treatment
to produce diploid plants. An example of the double haploid procedure using anther culture
follows:
Crossing generation: Crossing cultivar A and Cultivar B
F1 Generation: Culture Anther to produce 2000 t0 3000 haploid plants.
F2 Generation: Double chromosome of the haploid plants and harvest seeds from double haploid
plants produced.
F3 Generation: Grow progeny rows from double haploid plants and harvest seeds from superior
rows.
F4 Generation: Grow progeny rows in the field and select superior rows.
F5 Generation: Grow Preliminary Yield Trial.
F6 to F8 Generation: Continues yield trials.
F9 and F10 Generation: Increase and distribute superior lines as a new cultivars.
Double haploid plants are normally homozygous at all loci and it is unnecessary to grow
segregating generation. Lines generated by the double-haploid procedures may reach preliminary
yield trials two to three generation earlier than with the pedigree- selection or Bulk selection
procedures. Like the single seed descent procedure, early generations are not exposed to
environmental stresses in the field, and attrition of lines is greater in initial field evaluation trials
than with pedigree selection or bulk population procedures, in which early generations are field
grown. The double haploid plants should be vigorous, stable, free from tissue culture induced
variations, and represents a random selection of F1 pollen gametes.
5. Somaclonal Variation
Genetic Variability is the essential component of any breeding program designed to improve the
characterstics of crop plants. The variability generated by the use of a tissue culture cycle has
been termed somaclonal variation by Larkin and Scowcroft (1981). They defined a tissue culture
cycle as a process that involves the establishment of a dedifferentiated cell or tissue culture under
different conditions, proliferation for a number of generations and the subsequent regeneration of
plants. In other words one imposes a period of callus proliferation between an explants and the
regeneration of plants. The initiating explants for a tissue culture cycle may come virtually from
any plant organ or cell type including embryos, microspores, roots, leaves and protoplasts.
Historically, it became accepted dictum that all plants arising from tissue culture should be exact
7. copies of the parental plants. However phenotypic variants were frequently observed amongst
regenerated plants. These were usually dismissed earlier as tissue culture artifact due to the
recent exposure of exogenous phytoharmone, and sometimes they were labeled as epigenetic
events. However, evidence has now shown that these variants are not artifacts but variation
arising due to culture of cells and this has been termed as somaclonal variation. The cause of
variation is attributed to change in the chromosomal number and structure. Two schemes, with
and without in vitro selection, have been generally followed for getting somaclonal variation in
crop plants.
Explant
Explant derived callus
Shoot regeneration
Plant
Transfer to the field
Screening for disease traits
Agronomical traits
Fig : A flow diagram for generation of Somaclonal variation without in-vitro selection.
Genetic variation in Somatic cell cultures includes a wide mutation spectrum such as point
mutations, Chromosomal rearrangements, inversion, duplications, polyploidy, aneuploidy and
deletion. Either qualitatively or quantitatively inherited characters may be affected by the tissue
culture- induced mutation.
8. 6. Mutation Breeding:
Mutation is the sudden heritable change in a characteristic of organisms. Clearly, a mutation may
be the result of a change in gene ,a change in chromosome(s) that involves several genes or
change in plasma gene(genes present in cytoplasm, e.g. chloroplast, mitochondria etc which have
circular DNA , as chromosome).Mutation produced by change in the base sequence of gene (as a
result of base pair transition or transversion , deletion, duplication or inversion ,etc) are known
as gene or point mutation. Some mutation can be produced by change in chromosome structure,
or even in chromosome number: they are termed as chromosomal mutations.
Mutation occurs in a natural population at low rate; these are known as spontaneous mutations.
The frequency of spontaneous mutation is generally is one in 10 lacks i.e.10-6
but different genes
shows different mutation rates .for example R locus in maize mutates at a frequency of 4.92×10-
4
, Su 2.4×10-6,
while Wx appears to be highly stable. Mutation can be artificially induced by
treating with a certain physical or chemical agents; such mutations are known as induced
mutation, and the agents used for producing mutation are termed as mutagens. The utilizationof
induced mutation for crop improvement is known as mutation breeding.
Application of mutation breeding
Mutation breeding has been used for improving both the oligogenic as well as polygenic
character. It has been used to improve both the morphological as well as the physiological
characters, disease resistance and quantitative character including yielding ability. The various
applications of mutation breeding can be summarized as follows;
1.Induction of desirable mutation alleles, which may not be present in the germplasm or which
may be present ,but may not be available to the breeder due to political and geophysical reasons.
2. It is useful in improving specific characteristics of a well adapted high yielding variety. This is
particularly so in case of clonal crops due to their highly homozygous nature.
3. Mutagenesis is very useful in improving various quantative characters including the yield.
Several varieties have been developed using this technique.
4. F1 hybrids from the intervarietal crosses may be treated with the mutagens in order to improve
genetic variability by inducing mutations and by facilitating recombination among linked genes.
5. Irridation of interspecific hybrids has been done to produce translocations. This is done to
transfer a chromosome segment carrying a desirable gene from the alien chromosome to the
chromosome of cultivated species.
9. 7. Gene Pyramiding:
The development of molecular genetics and associated technology like MAS has led to the
emergence of a new field in plant breeding-Gene pyramiding. Pyramiding involves stacking
multiple genes leading to the simultaneous expression of more than one gene in a variety to
develop durable resistance expression. Introgression of multiple QTLs/genes for a solitary trait
or multiple traits into a cultivar that is deficient for these traits is known as ‘‘gene pyramiding’’.
One of the most important uses of gene pyramiding is the transfer of multiple disease resistance
genes for imparting durable disease .Pyramiding of genes for certain traits (such as for disease
resistance) following conventional backcrossing is tedious, time-consuming and difficult,
although successful pyramiding of resistance against all the three rusts [leaf (LR), stem (SR), and
yellow (YR) rusts] in wheat was achieved in India through conventional backcrossing technique
by B. P. Pal and coworkers as early as the 1950s (Gupta, 2007). With the availability of
molecular markers, it has now become much easier for breeders to combine desirable alleles at a
number of loci in a relatively short period of time .MAS has been successfully utilized in several
major crops to pyramid a number of targeted genes .In wheat, gene pyramiding using MAS has
been achieved for resistance against leaf rust (Cox et al., 1994; Gupta et al.2005; Singh et
al.2004; Nocente et al.,2007), powdery mildew (Liu et al.,2000; Wang et al.,2001). The success
of gene pyramiding depends upon several critical factors, including the number of genes to be
transferred, the distance between the target genes and flanking markers, the number of genotype
selected in each breeding generation, the nature of germplasm etc. Innovative tools such as DNA
chips, micro arrays, SNPs are making rapid steps, aiming towards assessing the gene functions
through genome wide experimental approaches.
8. Genetic Engineering:
Plant Genetic engineering refers to the transfer of foreign DNA which codes for specific genetic
information, from a donor species into a recipient plant species by means of a bacterial plasmid,
virus, or the vector. The procedure is also referred to as transformation. For the plant breeder,
plant genetic engineering has the potential for transferring a desirable foreign gene from a wide
range of source, including non- plant genetic material, into an economic crop species without
sexual hybridization. In many respects, plant genetic engineering (transformation) is comparable
to the back cross method of breeding in which desirable genes are transferred to recipient
genotypes by a succession of crosses. The molecular biologist inserts a segment of DNA that
code for desirable traits into the plant genotype where it replicates and is expressed in the new
plant genotypes. The crop species that have been genetically transformed with foreign DNA
includes corn, alfa alfa, potato, cauliflower, soybean, lettuce, sunflower, carrot, canola, cotton,
tomato etc.
10. Genetic Transformation: The transfer of the gene is mediated with the bacterial pathogen
Agrobacterium tumefaciens which is able to transfer a piece of its DNA (T-DNA) into DNA of
the plant resulting in the new, genetically transferred plant cell. Agrobacterium tumefaciens
infect plants by transferring T- DNA of the Ti- plasmid into plant cells and the t-DNA becomes
incorporated into the plant DNA’s , hence causing the crown gall disease.The gall of the tumour
are developed because the T-DNA from the bacteria has genes which regulates the biosynthesis
of the plant harmone IAA and Cytokinin. After plant become infected with A.tumefaciens,
abnormal level of IAA and cytokinin causes’ anomalous growth and tumer formation. Mutants of
A.tumefaciens have been developed in which the T-DNA doesnot produce IAA or cytokinin.
Foreign DNA is incorporated in to these non harmone producing A.tumefaciens strains as part of
the T-DNA. As, a result the modified A.tumefaciens as a vehicle to introduce the foreign genes
into the plants. This process now makes it possible to genetically engineered specific crop plants.
Steps, involving transformation:
Identification Isolation Introduction
(gene) (gene) (host)
Transmission Regeneration Selection & Integration
(Progeny) Expression genome
8. Genomic Selection:
It has been predicted for over two decades that molecular marker technology would reshape
breeding programs and facilitate rapid gains from selection. Currently, however, marker-assisted
selection (MAS) has failed to significantly improve polygenic traits. While MAS has been
effective for the manipulation of large effect alleles with known association to a marker, it has
been at an impasse when many alleles of small effect segregate and no substantial, reliable effects
can be identified.
The weaknesses of traditional MAS come from the way MAS splits the task into two
components, first identifying QTL and then estimating their effects. QTL identification
methods can make MAS poorly suited to crop improvement: (i) Biparental populations may be
used that are not representative and in any event do not have the same level of allelic diversity
and phase as the breeding program as a whole (ii) the necessity of generating such populations is
costly such that the populations may be small and therefore underpowered; (iii) validation of
discoveries is then warranted, requiring additional effort; (iv) the separation of QTL identification
from estimation means that estimated effects will be biased, and small-effect QTL will be missed
entirely as a result of using stringent significance thresholds. Association mapping (AM)
11. applied directly to breeding populations has been proposed to mitigate the lack of relevance
of biparental populations in QTL identification and QTL have been mapped in this way.
This practice nevertheless retains the disadvantage of biased effect estimates and therefore poor
prediction of line performance.
GS emerged out of a desire to exploit high density parallel genotyping technologies. At such
high densities, it was assumed that linkage phase between markers or haplotype blocks of
markers and casual polymorphism would be consistent across families so that population-wide
estimates of marker effects would be meaningful. GS uses a ‘training population’ of individuals
that have been both genotyped and phenotyped to develop a model that takes genotypic data
from a ‘candidate population’ of untested individuals and produces genomic estimated breeding
values (GEBVs). These GEBVs say nothing of the function of the underlying genes but they
are the ideal selection criterion in the plant breeding context, untested individuals would belong
to a broader population defined as a crop market class or the breeding program as a whole. In
simulation studies, GEBVs based solely on individuals’ genotype have been remarkably accurate.
These accuracies have held up in empirical studies of dairy cattle, mice and in biparental
populations of maize, barley and Arabidopsis.GS is revolutionizing both animal and plant
breeding.
9. Quantitative Trait Loci (QTL) Mapping:
A quantitative trait is governed by polygenes and is markedly affected by the environment. As a
result, it shows a continuous variation as opposed to the discrete variation that is characterstics of
qualitative traits. Polygenes are those genes that have small and cumulative effect on the
concerned traits, and several polygenes affect a single trait. Quantitative trait loci (QTL) are a
position in a chromosome that contains one or more polygenes involved in the determination of a
quantitative traits.
QTL mapping involves testing DNA markers throughout the genome for the likelihood that they
are associated with a QTL. Individuals in a suitable mapping population are analyzed in terms of
DNA marker genotypes and the phenotypes of interest. For each DNA marker, individuals are
split into classes according to marker genotype. A significant difference between the DNA
marker and the trait of interest indicates a linkage between the DNA marker and the traits of
interest i.e., the DNA marker is probably linked to a QTL controlling the phenotypes of interest.
The mapping of the QTL is done using the markers restriction fragment length polymorphism
(RFLP), randomly amplified polymorphic DNA (RAPD), microsatellite or simple sequence
repeat (SSR), amplified fragment length polymorphism (AFLP), single nucleotide polymorphism
(SNP) markers have been developed in a range of crops.
The mapping population must be relatively large in order to detect QTLs having minor effects,
and the biological relevance of the uncovered QTLs depends on the cut-off chosen for the
statistical significance. In QTL mapping, environmental factor and genetics background have a
marked impact on the results; some QTLs may be detectable in some but not in other
environment. One of the most powerful applications of QTL mapping is to analyze gene ×gene
and gene×environment interaction.
12. 10. Polyploidy Breeding:
Ploidy refers to the number of copies of the entire chromosome set in a cell of an individual. The
complete chromosome set is characteristic of, or basic to, a species. A set of chromosomes (the
genome) is designated by “x”. Furthermore, the basic set is called the monoploid set. The
haploid number (n) is the number of chromosomes that occurs in gametes. This represents half
the chromosome number in somaticcells, which is designated 2n. A diploid species, such as corn, has
n =10 and 2n=20. Also, a diploid species has 2n =2x in its somatic cells, and n =x in its gametes.
Polyploidy is the heritable condition of possessing more than two complete sets of chromosomes.
Most polyploids have an even number of sets of chromosomes, with four being the most
common (tetraploidy).
Fig. | Evolutionary alternation of diploidy and polyploidy.
Diploid
Speciation
DiploidspeciesAA Diploidspecies BB
2Ngamete
2N + 1N gametes
2Ngamete
F1(AB)
2Ngamete
Duplication
Triploid(AAA)
2N + 2N
t
Autotetrapoloid (AAAA) Allotetrapoloid (AABB)
Partially diploidized tetraploids
Diploid
13. Autoploids: Autoploids comprise duplicates of the same genome. Autoploids are useful in making
alloploids and wide crosses. Natural autoploids of commercial importancecommercial value
include banana, a triploid, which is seedless (diploid bananas have hard seeds not desirable in
production for food). Other important autoploids are tetraploid crops such as alfalfa, peanut,
potato, and coffee. Spontaneous autoploids are very important in the horticultural industry where
the gigas feature has produced superior varieties of flowering ornamentals of narcissus, tulip,
hyacinth, gladiolus, and dahlia among others.
Alloploids
Allopolyploid comprises of 2 or more distinct genome, generally each genome has two
copies.A number of economically important crops are alloploids. These include food crops
(e.g., wheat, oat), industrial crops (e.g., tobacco, cotton, sugarcane), and fruits crops (e.g.,
strawberry, blueberry). These crops, by definition, contain a combination of different genomes.
Dubbed the triangle of U, it describes the origins of three Brassica species by alloploidy. The
diploid species involved are turnip or Chinese cabbage (B. campestris, n=10), cabbage or kale (B.
oleracea, n=9), and black mustard (B. nigra, n =8). For example, B. napus has 2n =38, being a
natural amphiploid of B. oleracea and B. campestris. In cereal crops, wheat is a widely studied
alloploid that comprises genomes from three species. Cultivated common wheat (Triticum
aestivum) is a hexaploid with 21 pairs of chromosomes and is designated AABBDD. The AA
genome comes from T. monococcum. Tetraploid wheats have the genomic formula AABB.
wheat (T. dicoccum) crossed naturally with Aegilops squarrosa (DD) to form common wheat.
Fig.Thetriangleof U showingtheoriginsof variousalloploidsinBrassica. Fig. The evolution of the Hexaploid Wheat
B. carinata
(2n = 34)
(e g wild
B. napus
(2n = 38)
(e g rutabaga
B.
juncea
(2n
= 36)
(e.g.,
brown
B.
oleracea
(2n
= 18)
n
9
n
9
n
8
n
10
B. nigra
(2n
= 16)
n
8
n
10
B.
campestri
s
(2n = 20)
Triticum monococcum Unknown
BB(2n = 2x = 14) × (Aegilops speltoides?)
(AA)
2n = 2x = 14
Chromosome doubling
T. turgidum T.tauschii 2n= 14
(AABB)= 28 × (DD)
3x = 21 (ABD)
Chromosome doubling
T.aestivum 2n = 6x
= 42 (AABBDD)
14. Conclusion
Conventional breeding methodologies have extensively proven successful in development of
plant cultivars and germplasm. The most renowned examples include the semi-dwarf high-
yielding cultivars of cereals developed during the Green Revolution and the hybrid rice
developed in 1970s. However, conventional breeding is still dependent to a considerable extent
on subjective evaluation and empirical selection. It is tedious, time-consuming and difficult.
Scientific breeding needs less experience and more science, i.e. practical and accurate evaluation,
and effective and efficient selection. Molecular marker-assisted breeding (MAB) has brought
great challenges, opportunities and prospects for conventional breeding. The rapid development
of molecular markers (particularly DNA markers) and continuous improvement of molecular
assays has led to the birth of a new member in the family of plant breeding - molecular marker-
assisted breeding (MAB). The extensive use of molecular markers in various fields of plant
science, e.g. germplasm evaluation, genetic mapping, map-based gene discovery,
characterization of traits and crop improvement, has demonstrated that molecular technology is a
powerful and reliable tool in genetic manipulation of agronomically important traits in crop
plants . The significant advantage offered by the aseptic method of clonal propagation
(Micropropagaion) over the Conventional methods is that in a relatively short span of time and
space, a large number of plants can be produced starting from a single individuals. The genomic
selection , Gene pyramiding, MAS(Marker Assisted Selection), Mapping of the QTL(
Quantitively Trait Loci) are the emerging highly efficient technique which are in use nowadays
for the improvement of the crop species to revolutionize the world.
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