Bread wheat is an allohexaploid species that evolved through two hybridization events followed by chromosome doubling. The first event involved hybridization of Triticum urartu and Triticum speltoides, producing a tetraploid species. The second event involved hybridization of the tetraploid with Triticum tauschii, producing hexaploid wheat with three complete genome sets. Most evidence now suggests the tetraploid intermediate was produced from hybridization of Triticum urartu and Aegilops speltoides, not Triticum speltoides as previously thought. Hexaploid wheat then evolved on farmers' fields through hybridization of the tetraploid or domesticated em
Plant exploration, germplasm collection, conservation and utilizationSyed Zahid Hasan
Sequentially given germplasm exploration, collection, conservation,evaluation and utilization sof Agroforestry plants.
Some information and pictures collected from google.
Mutation breeding is a technique used to induce desirable mutations in crops to develop new varieties. It has been used successfully to create varieties with traits like higher yield, disease resistance, drought tolerance, and altered plant architecture. Desirable mutations are induced using physical mutagens like radiation or chemical mutagens and selected over multiple generations. Notable achievements include releasing over 2,000 new mutant varieties worldwide, with improvements in traits like yield, plant height, maturity, and seed size in various crops. While most mutations are undesirable, mutation breeding is an effective way to introduce new variation for crop improvement.
The term balanced tertiary trisomic has three words of which (1) “trisomic” indicates the presence of extra chromosome, (2) “tertiary” indicates that the extra chromosome is a trans-located chromosome, and (3) “balanced” refers to the breeding behaviour of the trisomic.
Ramage defined the BTT as a tertiary trisomic constructed in such a way that the dominant allele of a marker gene, closely linked with the translocation breakpoint of the extra chromosome is carried on the extra chromosome, and the recessive allele is carried on the two normal chromosomes that constitute the diploid complement. The dominant marker gene may be located on the centromere segment or the trans-located segment of the extra chromosome.
GPB 311: Wheat- Centre of origin, distribution of species, wild relatives and major breeding objectives and procedures for development of varieties and hybrids for improvement yield, adoptability, stability, biotic and abiotic stress tolerance and quality in Wheat
22. Polyploidy in plant breeding in crop improvementNaveen Kumar
Polyploidy refers to organisms that have more than two complete sets of chromosomes. It occurs naturally in plants through processes like autopolyploidy, where multiple chromosome sets are from the same species, and allopolyploidy, where chromosome sets are from different species. Polyploidy provides benefits like increased size, vigor and fertility restoration in some cases. It has played an important role in crop evolution, with many important crops being polyploid like potato, banana and coffee. Polyploidy can be artificially induced using techniques like colchicine treatment which inhibits chromosome separation. This has applications in crop improvement through creating new varieties and restoring fertility in interspecific crosses.
Bread wheat is an allohexaploid species that evolved through two hybridization events followed by chromosome doubling. The first event involved hybridization of Triticum urartu and Triticum speltoides, producing a tetraploid species. The second event involved hybridization of the tetraploid with Triticum tauschii, producing hexaploid wheat with three complete genome sets. Most evidence now suggests the tetraploid intermediate was produced from hybridization of Triticum urartu and Aegilops speltoides, not Triticum speltoides as previously thought. Hexaploid wheat then evolved on farmers' fields through hybridization of the tetraploid or domesticated em
Plant exploration, germplasm collection, conservation and utilizationSyed Zahid Hasan
Sequentially given germplasm exploration, collection, conservation,evaluation and utilization sof Agroforestry plants.
Some information and pictures collected from google.
Mutation breeding is a technique used to induce desirable mutations in crops to develop new varieties. It has been used successfully to create varieties with traits like higher yield, disease resistance, drought tolerance, and altered plant architecture. Desirable mutations are induced using physical mutagens like radiation or chemical mutagens and selected over multiple generations. Notable achievements include releasing over 2,000 new mutant varieties worldwide, with improvements in traits like yield, plant height, maturity, and seed size in various crops. While most mutations are undesirable, mutation breeding is an effective way to introduce new variation for crop improvement.
The term balanced tertiary trisomic has three words of which (1) “trisomic” indicates the presence of extra chromosome, (2) “tertiary” indicates that the extra chromosome is a trans-located chromosome, and (3) “balanced” refers to the breeding behaviour of the trisomic.
Ramage defined the BTT as a tertiary trisomic constructed in such a way that the dominant allele of a marker gene, closely linked with the translocation breakpoint of the extra chromosome is carried on the extra chromosome, and the recessive allele is carried on the two normal chromosomes that constitute the diploid complement. The dominant marker gene may be located on the centromere segment or the trans-located segment of the extra chromosome.
GPB 311: Wheat- Centre of origin, distribution of species, wild relatives and major breeding objectives and procedures for development of varieties and hybrids for improvement yield, adoptability, stability, biotic and abiotic stress tolerance and quality in Wheat
22. Polyploidy in plant breeding in crop improvementNaveen Kumar
Polyploidy refers to organisms that have more than two complete sets of chromosomes. It occurs naturally in plants through processes like autopolyploidy, where multiple chromosome sets are from the same species, and allopolyploidy, where chromosome sets are from different species. Polyploidy provides benefits like increased size, vigor and fertility restoration in some cases. It has played an important role in crop evolution, with many important crops being polyploid like potato, banana and coffee. Polyploidy can be artificially induced using techniques like colchicine treatment which inhibits chromosome separation. This has applications in crop improvement through creating new varieties and restoring fertility in interspecific crosses.
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.
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.
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.
Role of mutation breding in crop improvement Sanjay Kumar
This document summarizes a seminar on the role of mutation breeding in crop improvement. It discusses types of mutations, mutagens used, procedures for mutation breeding including choice of material and mutagen dose, screening and selection of mutants, achievements and major varieties developed through mutation breeding in India. Key advantages are that mutation breeding is a cheap and rapid method to develop new varieties and induce novel alleles. Limitations include the low frequency of desirable mutants and difficulties identifying micro-mutations. Mutation breeding has significantly contributed to global food security by developing new crop varieties.
The document provides information about the fundamentals of plant breeding course including the introduction and acclimatization topic. It defines introduction as growing genotypes in a new environment and lists objectives like obtaining new crops, serving as high yielding varieties, and being used in crop improvement. It also discusses the history of plant introductions to India, types of introductions, procedures involving procurement, quarantine, evaluation and distribution. Important plant introduction agencies and some prominent introductions are listed. The merits and demerits of introductions are outlined. Acclimatization is defined as the process where organisms adjust to environmental changes and performance improves over generations in the new environment through natural selection.
This document discusses plant introduction as a method of plant breeding. It begins by defining plant introduction as transferring plant genotypes or groups of genotypes to new areas where they have not been previously grown. The document then covers the history of plant introduction, the different types of plant introduction, the purposes of plant introduction, agencies involved in plant introduction, and the process of acclimatization. It also discusses the merits and demerits of plant introduction as a plant breeding method.
Thomas Fairchild was the first to create an artificial plant hybrid in 1717 between Sweet William and Carnation pink, called "Fairchild's Mule". Important developments in the pre-Mendelian era included domestication of major crops by 1000 BC, and the first description of the cell in 1665. The Mendelian era saw the rediscovery of Mendel's laws in 1900 and the development of the first commercial maize hybrid in 1917. The post-Mendelian era brought the discovery of cytoplasmic male sterility in rice in 1933 and transposable elements in 1950. Modern developments include the first transgenic plant in 1983, Bt cotton in 1987, and the Protection of Plant Varieties and Farmers'
This document discusses heterosis breeding in rice and wheat. It provides an introduction to hybrid rice technology in India, including the history and development of hybrid rice varieties. Key points covered include:
- Rice is a staple crop for over 70% of the Indian population. Hybrid rice was first developed in China in the 1970s and introduced to India in the late 1980s.
- Different hybrid rice production systems are described, including cytoplasmic male sterility (CMS) systems like three-line hybrids, and genic male sterility systems like photoperiod sensitive genic male sterility.
- Over 70 hybrid rice varieties have been released in India so far by public and private institutions. Popular hybrids
1. Inbred lines are developed through repeated self-pollination or inbreeding of plants over multiple generations to produce genotypes that are homozygous and genetically uniform.
2. The pedigree method is most commonly used to develop maize inbred lines, involving self-pollination over 6-7 generations with selection of desirable plants each generation.
3. Doubled haploid lines can also be used, in which haploid cells are induced and then chromosome doubled to instantly produce completely homozygous lines.
The document discusses the production of double haploid plants through anther and pollen culture techniques. It provides background on the history of double haploid development, the importance of double haploids in plant breeding, and methods used to induce haploids including anther culture, pollen culture, ovary slice culture, and ovule culture. Key factors influencing anther culture success are also reviewed, such as genotype, culture medium, microspore stage, temperature, and donor plant physiology. Advantages and disadvantages of generating double haploid lines are presented.
Cytogenetic techniques for gene location and transferPratik Satasiya
This document discusses various cytogenetic techniques for gene location and transfer. It describes techniques for locating genes such as using structural and numerical chromosomal aberrations, chromosome banding, and in situ hybridization. Structural aberrations discussed include deficiencies, inversions, and translocations. Numerical aberrations discussed include aneuploids like trisomics, monosomics, and nullisomics. The document also describes techniques for transferring genes between species such as transferring whole genomes, whole chromosomes, chromosome arms, and through various types of interchanges. Specific examples of using these techniques in plants are provided.
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.
Definitions, variety production release and notification in india and pakistsudha2555
1. The document discusses concepts related to variety release and seed production systems in India and other countries like Pakistan. It defines key terms and describes procedures for variety testing, release, and notification.
2. Variety testing in India involves evaluation through station trials, multilocation trials, national trials, and on-farm trials over several years before potential release. Superior varieties identified through this process may be recommended for release.
3. Release and notification involves recommendation by variety release committees at the state and national level, followed by an official notification from the Government of India allowing commercial seed production.
This document provides information about a plant breeding course including its objectives. It begins with details about the course such as its name, credit hours, and presenter. It then discusses definitions of plant breeding and the objectives of plant breeding which include higher yields, improved quality, disease and insect resistance, and changes in maturity duration among other traits. The document lists 12 main objectives of plant breeding and provides examples for each one. It concludes with information about international agricultural research centers.
Mutation breeding is a tool for crop improvement that induces mutations using physical or chemical mutagens. Over 3,200 mutant varieties have been released globally in over 70 plant species. Key milestones included the first induced mutations in plants in 1927 and development of the first induced mutant variety in 1936. Procedures involve choosing plant material, applying mutagens like radiation or chemicals, handling mutated plants, and screening generations to select desirable traits. Successful examples include developing semi-dwarf, disease resistant, early maturing, and stress tolerant rice, wheat, barley, peanut, and chickpea varieties. Mutation breeding has made major contributions to global food production.
This document describes the pedigree method of plant breeding. The pedigree method involves selecting individual plants from segregating generations like F2 and recording the parent-offspring relationships. Key steps include growing F1 plants to produce F2 seeds, selecting plants from the F2 generation based on traits, growing progeny rows from selected F2 plants in F3, continuing selection and growing of progeny rows from subsequent generations to achieve homozygosity and stable lines for yield trials. The pedigree method allows for selection and development of pure lines from segregating populations.
Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA). Passed from parents to offspring, DNA contains the specific instructions that make each type of living creature unique.
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.
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.
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.
Role of mutation breding in crop improvement Sanjay Kumar
This document summarizes a seminar on the role of mutation breeding in crop improvement. It discusses types of mutations, mutagens used, procedures for mutation breeding including choice of material and mutagen dose, screening and selection of mutants, achievements and major varieties developed through mutation breeding in India. Key advantages are that mutation breeding is a cheap and rapid method to develop new varieties and induce novel alleles. Limitations include the low frequency of desirable mutants and difficulties identifying micro-mutations. Mutation breeding has significantly contributed to global food security by developing new crop varieties.
The document provides information about the fundamentals of plant breeding course including the introduction and acclimatization topic. It defines introduction as growing genotypes in a new environment and lists objectives like obtaining new crops, serving as high yielding varieties, and being used in crop improvement. It also discusses the history of plant introductions to India, types of introductions, procedures involving procurement, quarantine, evaluation and distribution. Important plant introduction agencies and some prominent introductions are listed. The merits and demerits of introductions are outlined. Acclimatization is defined as the process where organisms adjust to environmental changes and performance improves over generations in the new environment through natural selection.
This document discusses plant introduction as a method of plant breeding. It begins by defining plant introduction as transferring plant genotypes or groups of genotypes to new areas where they have not been previously grown. The document then covers the history of plant introduction, the different types of plant introduction, the purposes of plant introduction, agencies involved in plant introduction, and the process of acclimatization. It also discusses the merits and demerits of plant introduction as a plant breeding method.
Thomas Fairchild was the first to create an artificial plant hybrid in 1717 between Sweet William and Carnation pink, called "Fairchild's Mule". Important developments in the pre-Mendelian era included domestication of major crops by 1000 BC, and the first description of the cell in 1665. The Mendelian era saw the rediscovery of Mendel's laws in 1900 and the development of the first commercial maize hybrid in 1917. The post-Mendelian era brought the discovery of cytoplasmic male sterility in rice in 1933 and transposable elements in 1950. Modern developments include the first transgenic plant in 1983, Bt cotton in 1987, and the Protection of Plant Varieties and Farmers'
This document discusses heterosis breeding in rice and wheat. It provides an introduction to hybrid rice technology in India, including the history and development of hybrid rice varieties. Key points covered include:
- Rice is a staple crop for over 70% of the Indian population. Hybrid rice was first developed in China in the 1970s and introduced to India in the late 1980s.
- Different hybrid rice production systems are described, including cytoplasmic male sterility (CMS) systems like three-line hybrids, and genic male sterility systems like photoperiod sensitive genic male sterility.
- Over 70 hybrid rice varieties have been released in India so far by public and private institutions. Popular hybrids
1. Inbred lines are developed through repeated self-pollination or inbreeding of plants over multiple generations to produce genotypes that are homozygous and genetically uniform.
2. The pedigree method is most commonly used to develop maize inbred lines, involving self-pollination over 6-7 generations with selection of desirable plants each generation.
3. Doubled haploid lines can also be used, in which haploid cells are induced and then chromosome doubled to instantly produce completely homozygous lines.
The document discusses the production of double haploid plants through anther and pollen culture techniques. It provides background on the history of double haploid development, the importance of double haploids in plant breeding, and methods used to induce haploids including anther culture, pollen culture, ovary slice culture, and ovule culture. Key factors influencing anther culture success are also reviewed, such as genotype, culture medium, microspore stage, temperature, and donor plant physiology. Advantages and disadvantages of generating double haploid lines are presented.
Cytogenetic techniques for gene location and transferPratik Satasiya
This document discusses various cytogenetic techniques for gene location and transfer. It describes techniques for locating genes such as using structural and numerical chromosomal aberrations, chromosome banding, and in situ hybridization. Structural aberrations discussed include deficiencies, inversions, and translocations. Numerical aberrations discussed include aneuploids like trisomics, monosomics, and nullisomics. The document also describes techniques for transferring genes between species such as transferring whole genomes, whole chromosomes, chromosome arms, and through various types of interchanges. Specific examples of using these techniques in plants are provided.
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.
Definitions, variety production release and notification in india and pakistsudha2555
1. The document discusses concepts related to variety release and seed production systems in India and other countries like Pakistan. It defines key terms and describes procedures for variety testing, release, and notification.
2. Variety testing in India involves evaluation through station trials, multilocation trials, national trials, and on-farm trials over several years before potential release. Superior varieties identified through this process may be recommended for release.
3. Release and notification involves recommendation by variety release committees at the state and national level, followed by an official notification from the Government of India allowing commercial seed production.
This document provides information about a plant breeding course including its objectives. It begins with details about the course such as its name, credit hours, and presenter. It then discusses definitions of plant breeding and the objectives of plant breeding which include higher yields, improved quality, disease and insect resistance, and changes in maturity duration among other traits. The document lists 12 main objectives of plant breeding and provides examples for each one. It concludes with information about international agricultural research centers.
Mutation breeding is a tool for crop improvement that induces mutations using physical or chemical mutagens. Over 3,200 mutant varieties have been released globally in over 70 plant species. Key milestones included the first induced mutations in plants in 1927 and development of the first induced mutant variety in 1936. Procedures involve choosing plant material, applying mutagens like radiation or chemicals, handling mutated plants, and screening generations to select desirable traits. Successful examples include developing semi-dwarf, disease resistant, early maturing, and stress tolerant rice, wheat, barley, peanut, and chickpea varieties. Mutation breeding has made major contributions to global food production.
This document describes the pedigree method of plant breeding. The pedigree method involves selecting individual plants from segregating generations like F2 and recording the parent-offspring relationships. Key steps include growing F1 plants to produce F2 seeds, selecting plants from the F2 generation based on traits, growing progeny rows from selected F2 plants in F3, continuing selection and growing of progeny rows from subsequent generations to achieve homozygosity and stable lines for yield trials. The pedigree method allows for selection and development of pure lines from segregating populations.
Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA). Passed from parents to offspring, DNA contains the specific instructions that make each type of living creature unique.
This document discusses cotton genomics and provides details about cotton species. It summarizes that cotton has a large and complex genome, with Gossypium hirsutum and G. barbadense being the most important cultivated species. The genome of G. raimondii is considered closest to the D-genome donor of tetraploid cotton. Resources like CottonDB provide genomic data on markers, genes, and genetic maps. Sequencing efforts aim to understand cotton evolution and support molecular breeding.
This document reports on a study comparing the karyotypes and protein profiles of three Trifolium species: T. alexandrinum, T. refeigratum, and T. repens. The results found that T. refeigratum and T. repens both have 16 pairs of chromosomes with one pair containing satellites, while T. alexandrinum has 8 pairs of chromosomes. Analysis of the karyotypes showed differences in symmetry indices between the species. Protein profile analysis via SDS-PAGE revealed clustering of T. alexandrinum separately from the other two species, indicating polymorphic protein bands that differ. The study provides cytological and protein evidence to compare the three clover species
Genetics is the study of heredity and variation in living organisms. Some key events in genetics include Mendel discovering the principles of heredity in 1865 and Watson and Crick determining the structure of DNA in 1953. In humans, each cell normally contains 23 pairs of chromosomes, including 22 pairs of autosomes and one pair of sex chromosomes. Important parts of chromosomes include the centromere and telomeres. Karyotyping involves analyzing an individual's chromosomes to detect abnormalities. Lyon's hypothesis explains X chromosome inactivation in females.
The document summarizes cytological features of green algae. It discusses nuclear structure, the cell cycle and processes of cell division including mitosis and meiosis. It describes different chromosome types observed such as long, small, polycentric and nucleolar organizing chromosomes. Karyotypes and chromosome numbers are provided for various orders of green algae. Methods used to study chromosomes including light microscopy, electron microscopy and fluorescence microscopy are mentioned. Important contributions to the field from researchers in India and abroad are also noted.
Karyotyping and idiograms are techniques used to study chromosomes. Karyotyping arranges chromosomes by size and structure, allowing comparison between species. Idiograms diagrammatically represent chromosome sets. Scientists use karyotyping to diagnose genetic disorders by examining chromosomes for abnormalities in number or structure. Chromosomes are classified by centromere position and banding patterns after staining. Karyotyping involves growing cells, arresting mitosis, staining, and arranging chromosomes for analysis. Common chromosomal abnormalities include aneuploidies like Down syndrome and sex chromosome disorders.
Karyotype analysis and evolution by MannatMannatAulakh
A karyotype is the number and appearance of chromosomes in a cell and can provide information about an organism's species. Key features used to characterize karyotypes include chromosome size, centromere position, and banding patterns. Karyotypes can be symmetric or asymmetric and are often represented visually using idiograms or karyograms. Analysis techniques like G-banding stain chromosomes to reveal identifying patterns. Comparing karyotypes across species provides insights into evolutionary mechanisms like centric fusion and fission that alter chromosome counts. In primates, chromosomal changes like the fusion that formed human chromosome 2 are important in lineage evolution.
Chromosomes are structures within the nucleus that carry genetic information. They are composed of DNA and proteins and are only visible during cell division. Chromosomes contain genes and come in varying numbers depending on the organism. They are organized into nucleosomes which aid in compactly packaging the long DNA molecules. Centromeres and telomeres are essential features that help segregate and provide stability to chromosomes during cell division.
Chromosomes are structures within the nucleus that contain DNA. They become visible during cell division and are the carriers of genetic information. Chromosomes are composed of chromatin fibers that coil and fold, making the chromosomes visible under a light microscope during cell division. Chromosomes vary in size and number between species. They contain DNA that is packaged with histone proteins to form chromatin. The basic repeating unit of chromatin is the nucleosome, which contains 146 base pairs of DNA wrapped around an octamer of histone proteins.
Chromosome structure and packaging of dnaDIPTI NARWAL
Chromosomes are structures that contain DNA and help transmit genetic information from parents to offspring. They exist in the nucleus of cells and vary in number between species. DNA is packaged into chromosomes through histone proteins that allow very long DNA strands to fit inside cells. DNA wraps around histone proteins to form structures called nucleosomes, which contain 147 base pairs of DNA wrapped around an octamer of histone proteins. Nucleosomes further compact DNA by forming a beads-on-a-string structure that can coil and fold, allowing the long DNA molecules to fit within cells.
This document provides information about yams, including their classification, cultivation, and key species. It discusses yams originating from Africa and Asia, with over 600 species worldwide, of which D. alata, D. cayenensis, D. rotundata, D. esculenta, D. bulbifera, D. nummularia, D. pentaphylla, D. hispida, D. trifida and D. dumetorum are the major cultivated ones. The document focuses on D. alata, D. dumentorum, and D. rotundata. It reviews literature around yam origins and classification. The objective is to determine the ploidy levels and
Polytene chromosome with respect to historical basis, occurrence, structural organisation, bands and inter bands, puff are briefly stated for basic idea.
You may find this interesting understand the reason behind the gaint structure of these chromosomes.
This study material is a compilation of various sources such as text books, website etc...
Enjoy the process of Learning
Thank you
This document provides information about karyotyping and cell division:
- It describes how karyotyping involves arranging chromosomes based on size and centromere position to identify abnormalities. Normal karyotypes are shown for several species.
- The stages of mitosis and meiosis are outlined, with mitosis producing identical daughter cells and meiosis resulting in halved chromosome number.
- Interphase, prophase, metaphase, anaphase, and telophase are the stages of mitosis described in detail. Cytokinesis then divides the cytoplasm.
This document discusses chromosomes and their structure. Some key points:
- Chromosomes are thread-like structures found in the nucleus that contain DNA. They can be seen during cell division.
- Chromosomes come in different shapes depending on the location of the centromere. They also have two arms labeled p and q.
- Humans have 46 chromosomes in their somatic cells. The number varies between species but is consistent within a species.
- Chromosomes contain DNA that is tightly packaged and organized through proteins like histones to fit inside the nucleus. Nucleosomes and chromatin compaction allow for the dense packing of DNA.
The mitotic and meiotic chromosome study in Vallenus malabaricus were performed from bone
marrow tissue and testes respectively. The mitotic metaphase plates showed diploid modal value 2n = 76±. The
meiotic showed diakinesis and metaphase stage with 38 bivalents confirming the diploid modal value 2n= 76±.
From Karyological analysis, the macrochromosomes were 20 in number and rests of the 56 chromosomes were
dot shaped acrocentric chromosomes. The macrochromosomes includes four pairs of metacentric, four pairs of
submetacentric one pair subtelocentric and one pair of telocentric chromosomes. The meiotic stages showed
diakinesis showing chiasma and crossing over stages. From Karyology study it is evident that order
Charadriiformes represents heterogeneity.
Polytene chromosomes are giant chromosomes that form in certain cell types through repeated rounds of DNA replication without cell division. This results in thousands of identical DNA strands aligned side by side. They are very large, up to 2000um long, and show characteristic banding patterns when stained. The bands correspond to regions of coiled DNA and contain genes, while interbands have less coiled DNA. Gene activity causes some bands to expand and puff out, indicating active transcription in those regions. Polytene chromosomes are useful for mapping genes and studying patterns of gene expression.
Karyotype analysis involves examining the number and appearance of chromosomes in a cell. It has been important for understanding cell biology, genetics, and evolution. Key developments include the first observation of chromosomes in 1842, the coining of the term "karyotype" in 1888, and defining karyotypes as phenotypic chromosome appearances in 1922. Karyotypes are studied by staining cells during cell division. Variations exist between sexes, germline/soma, populations, geography, and abnormalities. Chromosome number varies widely between species and changes during development, including elimination, diminution, and inactivation. Aneuploidy and polyploidy also contribute to karyotype diversity and evolution. Banding techniques like
Similar to Origin, Evolution, And Cytogenetic Studies In Rice (20)
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
Or: Beyond linear.
Abstract: Equivariant neural networks are neural networks that incorporate symmetries. The nonlinear activation functions in these networks result in interesting nonlinear equivariant maps between simple representations, and motivate the key player of this talk: piecewise linear representation theory.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Corrected slides: dtubbenhauer.com/talks.html
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
Travis Hills' Endeavors in Minnesota: Fostering Environmental and Economic Pr...Travis Hills MN
Travis Hills of Minnesota developed a method to convert waste into high-value dry fertilizer, significantly enriching soil quality. By providing farmers with a valuable resource derived from waste, Travis Hills helps enhance farm profitability while promoting environmental stewardship. Travis Hills' sustainable practices lead to cost savings and increased revenue for farmers by improving resource efficiency and reducing waste.
BREEDING METHODS FOR DISEASE RESISTANCE.pptxRASHMI M G
Plant breeding for disease resistance is a strategy to reduce crop losses caused by disease. Plants have an innate immune system that allows them to recognize pathogens and provide resistance. However, breeding for long-lasting resistance often involves combining multiple resistance genes
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
Unlocking the mysteries of reproduction: Exploring fecundity and gonadosomati...AbdullaAlAsif1
The pygmy halfbeak Dermogenys colletei, is known for its viviparous nature, this presents an intriguing case of relatively low fecundity, raising questions about potential compensatory reproductive strategies employed by this species. Our study delves into the examination of fecundity and the Gonadosomatic Index (GSI) in the Pygmy Halfbeak, D. colletei (Meisner, 2001), an intriguing viviparous fish indigenous to Sarawak, Borneo. We hypothesize that the Pygmy halfbeak, D. colletei, may exhibit unique reproductive adaptations to offset its low fecundity, thus enhancing its survival and fitness. To address this, we conducted a comprehensive study utilizing 28 mature female specimens of D. colletei, carefully measuring fecundity and GSI to shed light on the reproductive adaptations of this species. Our findings reveal that D. colletei indeed exhibits low fecundity, with a mean of 16.76 ± 2.01, and a mean GSI of 12.83 ± 1.27, providing crucial insights into the reproductive mechanisms at play in this species. These results underscore the existence of unique reproductive strategies in D. colletei, enabling its adaptation and persistence in Borneo's diverse aquatic ecosystems, and call for further ecological research to elucidate these mechanisms. This study lends to a better understanding of viviparous fish in Borneo and contributes to the broader field of aquatic ecology, enhancing our knowledge of species adaptations to unique ecological challenges.
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
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
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.
20240520 Planning a Circuit Simulator in JavaScript.pptx
Origin, Evolution, And Cytogenetic Studies In Rice
1.
2. INTRODUCTION
Rice is a diploid (2n=24), has a genome size of 430Mb and has
established cytogenetic stocks.
The cytogenetic stocks have been employed to develop
cytological, classical, and molecular linkage maps of rice.
The production of a series of MAALs from wide crosses has
enabled the introgression of economically useful alien genes into
cultivated rice.
3.
4. TAXONOMY
S.N: Oryza sativa
Chr No:-(2n=24)
Tribe- Oryzaea
Fam- Graminae
cultivated species of rice
i)Oryza sativa - Asian rice
ii) O. glaberrima- African rice.
The three races in cultivated Asian rice are
i) Indica
ii) Japonica (Sinica)
iii) Javanica.
5. Center of origin:
(Acc to Vavilov): (Indo – Burma )
(Acc to de Candello): South East Asia
The views regarding the origin of rice can be grouped in to two classes
viz.,
Monophyletic origin.
Polyphyletic origin
6. According to this theory both Asian rice and African rice arose
from a common parent (O.perennis). This view is the most
accepted one because both Asian rice and African rice are
similar except in glume pubescence, ligule size and colour of
pericarp which is red in African rice.
O.perennis
O.sativa
O.glaberrima
7. POLYPHYLETIC ORIGIN
Originated From several species.
Asian rice O.sativa have evolved in the region of South &
South East Asia from several species like Perennial
O.rufipogon; Annual O.nivara and O.spontanea.
African rice O.glaberrima have evolved in the region of
Tropical Africa from several species like O.longistaminata;
O.barthii; O.Staffii.
8. 8
COMMON ANCESTOR
(Pre perennis)
SOUTH AND SOUTH WEST ASIA TROPICAL AFRICA
O.rufipogon
(AA)
O.longistaminata
(AA)
O.nivara
(AA)
O.barthii
(Ag
Ag
)
O.sativa
(AA)
O.glaberrima
(Ag
Ag
)
O.Spontanea O.stapfi
Weedy
annual
Indica Japonica Javanica
Wild
perennial
Wild
annual
cultivated
annual
9.
10.
11. Sativa Complex Ploidy &
chromosome No.
Genome Distribut
ion
Useful Traits
O. sativa Diploid 2n=24 AA World
Wide
O.glaberrima Diploid 2n=24 AgAg Africa
O.barthii Diploid 2n=24 AgAg Africa Drought avoidance,
BLB resistant
O.longistaminata Diploid 2n=24 AgAg Africa Drought tolerance
O.nivara Diploid 2n=24 AA Tropical
Asia
Grassy stunt, virus
resistant& blast
resistant
O.rufipogan Diploid 2n=24 AA Tropical
Asia
Source of cms
,tolerance to
submergence
O.mesidionalis Diploid 2n=24 AA Tropical
Australia
O.glumacepetula Diploid 2n=24 AA South
America
12. Officinalis Complex Ploidy &
chromosome No.
Geno
me
Distribution Useful Traits
O. officinalis Diploid 2n=24 CC Tropical Asia to
New Guinea
O.eichinhgeri Diploid 2n=24 CC East and West
Africa
BPH,WBPH,GLH
resistant
O.rhizomatis Diploid 2n=24 CC Srilanka
O.minuta Tetraploid 2n=48 BBCC Philippines,
Paupua New
Guinea
BPH,WBPH,GLH
resistant
O.punctata Diploid 2n=24
Tetraploid 2n=48
BB
BBCC Africa
BPH
O.latifolia Tetraploid 2n=48 CCDD Latin America High biomass
production
O.alta Tetraploid 2n=48 CCDD Latin America High biomass
production & blast
resistant
O.grandiglumis Tetraploid 2n=48 CCDD South America High biomass
production
O.australiensis Diploid 2n=24 EE Australia Drought tolerance&
BPH resistant
13. Meyeriana Complex Ploidy &
chromoso
me No.
Genome Distribution Useful Traits
O. granulata Diploid
2n=24
FF South & South
East Asia
Shade tolerance
O. meyeriana Diploid
2n=24
FF Africa Shade tolerance
O. branchyantha Tetraploid
2n=48
FF New Guinea Yellow stem borer,
& leaf folder
resistant
O. schlecheri Tetraploid
2n=48
14. The cytology of rice, especially the meiosis, has been studied by Kuwada
(1910), Selim (1930) and Nandi (1936 unpublished), but owing to its
apparently diploid nature and the smallness of the chromosomes many
important details were omitted.
Secondary pairing was first observed by Kuwada (1910) in Oriyza sativa
L., from which evidence Lawrence (1931) tentatively concluded that O.
sativa is derived with 7 pairs of chromosomes, in common with the
majority of the Gramineae.
Yamaura (1933) suggested a possible origin of O. sativa by hybridization
between two ancestral species with 5 and 7 chromosomes respectively.
15. Somatic chromosome complement
The chromosomes of O. sativa are rather small, the longest
being about 2.8µ and the smallest 0.7µ long.
16. The size differences which exit make it possible to classify the 24
chromosomes of O. sativa L. into ten types. Of these ten types of
chromosomes, eight are present twice and two types are present four times,
making a total of 2n = 24 in the diploid complex.
The haploid complex of O. sativa may then be regarded as composed of two
different five-paired sets belonging to two different species in which two
chromosomes were duplicated, the two species concerned differing
somewhat in chromosome morphology.
These observations were verified from studies of meiotic chromosomes,
where the size differences and types of chromosomes are more marked.
18. The theory of secondary association of meiotic chromosomes originally
put forward by Darlington (1928) and systematized by Lawrence (1931)
implies that the chromosomes showing this kind of affinity are
phylogeneticalIy related to each other.
Secondary association is therefore "intimately connected with
allopolyploidy“.
Secondary pairing can be used as a measure of distant relationship between
the chromosomes present in a polyploid, and it will be so used in
determining the basic composition of the chromosomes in Oryza sativa L.
19.
20. In 1936, SAKAI concluded that 12 is not the basic
chromosome number of Oryza sativa in the strict sense, but that 5
is the primary number from which the 12 were derived.
In other words, Oryza sativa L. is a double hexasomic tetraploid
Cytological data supporting the above conclusion were :
(1) quadrivalent association of chromosomes at diakinesis and
metaphase I was observed,
(2) secondary association of the meiotic chromosomes was very
distinct, the maximum association being two groups of 3 and
three groups of two.
21. RAMANUJAM (1938), MORINAGA (1939), YASUI (1941), Hu (1958),
ISHII AND MITSUKURI (1960) made more detailed observations.
However, it is difficult to obtain distinct figures of chromosome
configurations because of their small size.
Pachytene chromosomes may be suitable for detailed observation. In
Oryza sativa, however, they do not always stain well, and the position of
the centromere cannot clearly be distinguished (YAO et al., 1958;
SHASTRY et al., 1960).
22. To solve these difficulties, the author have chosen haploid plants as his
experimental material, since in haploids each chromosome is represented
once and relatively distinct figures can be obtained.
He found that seven to eight different types of chromosomes could be
distinguished in a set, and that Oryza sativa and Oryza glaberrima showed
almost the same karyotype (Hu, 1958).
Comparing the data from haploid plants with those from diploids, he further
suggested that the various species of Oryza have similar karyotypes (Hu,
1961).
23. The 12 chromosomes are arranged in the order of their length (Hu, 1958).
The 21 cells observed also are arranged in the order of total chromosome
length. The variation in chromosome length among cells might be due to
contraction of chromosomes which varies with the mitotic stage. Each of
the 12 chromosomes is characterized as follows:
24. Chromosome 1:- longest chromosome. Sub-median. In late
prophase, the central part of the chromosome near the
constriction might be heterochromatic.
Chromosome 2. Submedian. At prometaphase, the long and short
arms appear to be of nearly the same length, but at metaphase the
primary and secondary constrictions in the long arm divide the
chromosome into three equal parts.
Chromosome 3. Median. At the end of the long arm there was
found a satellite-like granule in some cells, though it disappeared
at metaphase.
25. Chromosome 4. Median. Slightly shorter than chromosome 3.
Chromosomes 5 and 6. Submedian. It is difficult to distinguish
between them.
Chromosome 7. Submedian. Previously it have been considered to be
subterminal. This chromosome has one secondary constriction and a
satellite.
Chromosomes 8. Subterminal. It has a prominent satellite.
Chromosomes 9. Subterminal. Previously considered to be submedian,
at prometaphase chromosome 9 can be identified by the two arm
lengths and a darkly stained short arm.
26. Chromosomes 10 and 11. Submedian to median. They are small
and darkly stained even in late prophase and prometaphase. One
of them appears to be median at metaphase in the form of a V-
shaped chromosome.
Chromosome12. The smallest chromosome. Submedian. The
chromosome is so small that it is often difficult to find the
position of the centromere.
27. CHROMOSOME NUMBER AND SIZE
YAMAURA (1933) suggested a possible origin of O. sativa by
hybridization between two ancestral species with 5 and 7 chromosomes
respectively.
NANDI (1936), the original ancestor of rice had a basic number of 5
chromosomes, and the present number, n=12, is secondarily balanced.
The longest chromosome is about 2.8x10-6cm and the smallest is 0.7x10-
6cm.
27
28. From lengths, and the percentages of long-arm lengths of
individual chromosomes, it was found that the chromosomes could
be divided into six classes of different lengths represented by
chromosomes 1, 2, 3, 4 – 5 – 6 – 7 – 9, 8–10–11 and 12, and into
three classes of different arm ratios, 3 – 4 – 11 (median), 1– 2 – 5–
6– 7– 1 0– 1 2 (submedian), and 9–8 (subterminal) respectively.
It was also confirmed that two relatively small chromosomes have a
satellite each.
Most chromosomes seem to have heterochromatic segments.
Somatic pairing was found at metaphase.
31. To describe the karyomorphology of the haploid set of chromosomes,
we must determine length, position of constrictions, presence or absence
of satellites, and other characteristics. Previous findings for Oryza sativa
are compared with the results of the present study.
32. Pachytene analysis an ideal tool for the study of not only
chromosome morphology but also of chromosome pairing.
Employing this method, smaller differences between the
karyotypes, which are not detectable at metaphase, can be
revealed.
The morphology of bivalents differs between the species. The
karyotype of Oryza australiensis is highly heterochromatic.
Wild species have more symmetric karyotypes than cultivated
species.
The rate of condensation of individual chromosomes is of the
same order both within and among three varieties of Oryza
perennis.
33. KUWADA (1909, 1910) reported the development of the pollen grain, embryo
sac, and the formation of endosperm of rice. He determined the number of
chromosomes of rice as n = 12 and 2n = 24, and described in detail the
behavior of chromosomes during meiosis.
He observed that some of the chromosomes in the second division of
metaphase presented a paired arrangement, showing a tendency to form a
group of more than two. He also observed such a paired arrangement in the
somatic metaphase of the nucellar tissue.
34. Ichijima (1934) he induced mutations in rice by means of X-ray, ultraviolet
light and variation in temperature, and the mutant characters practically
covered all the types of spontaneous mutation previously reported in rice.
He classified the artificial mutations into two groups:
the mutant characters appeared in the first generation as the direct effect of
the treatment and
the mutant characters occurred in the second or third generation.
All gene mutations belonged to the first group; in the second group,
heteroploid, tetraploid and haploid plants appeared and triploids were most
common.
35. OKURA cross-pollinated 18 flowers of a tetraploid with the pollen grains of
diploid plants and obtained 11 seeds, of which eight germinated, producing
five diploid plants and three tetraploid plants (OKURA, 1940).
The author and KURIYAMA repeatedly tried in 1943 the reciprocal cross
between the diploid and tetraploid, but no hybrid was obtained.
The polyploid and haploid plants were studied from various points of interest by
many workers.
36. In the haploid, 9 microsporocytes in metaphase and early anaphase showed
distinctly 12 univalents. Such chromosomes were observed near the pole as
well as near the equator. At anaphase, 6–6 distribution of univalents to each
pole was observed most frequently; 5–6 and 4–8 distributions followed in
that order. The entire complement of 12 chromosomes were rarely found in
the same pole region.
In triploids, 36 chromosomes were usually arranged in 12 groups of 3 each
at diakinesis. In metaphase I usually 12 or more chromosomes are counted,
the largest number observed being 18 (6 III + 6 II + 6 I ). In the following
anaphase, the trivalent chromosomes disjoin to the 3 components, and one
travels to one pole and the other two to the opposite pole.
37. In tetraploids, 13-20 chromosomes were counted at diakinesis, the average
number being 16.04. In metaphase I, quadrivalents and bivalents were easily
identified and the maximum and minimum numbers of quadrivalents observed
were 12 and 6 respectively, the average number being 9.38. In the following
anaphase, the chromosomes disjoined into four homologues, which, as a rule,
were evenly distributed to each pole.
38. Chromosomal set of sativa is dissimilar to chromosomal
sets of minuta or latifolia, the genomic constitutions :
• Oryza sativa L. (2 n = 24) AA
• Oryza minuta (2 n = 48) BBCC
• Oryza latifolia (2 n = 48) CCDD
Reported on 12 interspecific hybrids, postulated the genomic
constitution of the 11 species ;
I. AA group: sativa, cubensis, glaberrima, breviligulata, perennis
II. CC group:officinalis
III. BBCC group: minuta, eichingeri
IV. CCDD group: latifolia, paraguaiensis.
•The genomic constitution of australiensis is not quite decided yet,
but it is clearly dissimilar to AA.
(MORINAGA, 1959; MORINAGA and
KURIYAMA, 1960)
39.
40. MORPHOLOGY OF PACHYTENE
CHROMOSOMES
i) Highly differentiated type: very thick and deeply stained
heterochromatic regions. eg: O. australiensis, O. meyeriana
ii) Undifferentiated and moderately heterochromatic: eg: O.
rufipogan, O. officinalis, O. longistaminata
iii) Undifferentiated and highly euchromatic pachytene
chromosomes: eg: O. sativa, O. glaberrima and O. nivara
40
41. Fig. Pachytene studies on Oryza sativa × officinalis hybrid.
1 – Pachynema showing 24 univalent chromosomes
2 – Late pachynema showing 24 unpaired chromosomes
3 – First metaphase showing 1 II + 22 I .
pachynema Late pachynema
42. PMCs at pachynema and early diplonema showed 24
unpaired chromosomes. This unpaired condition persisted till
metaphase I.
Lack of homology between the chromosomes of the two
species caused the nearly complete univalent formation in the
hybrid.
This findings support the earlier observations of NANDI
(1936, 1938), RAMANUJAM (1937), MORINAGA and
KURIYAMA (1960) and NEZU et al. (1960) that sativa and
officinalis have two distinct genomes, A and C, respectively.
43. Fig. Pachytene stage of the parents and their F 1 hybrid.
1 – Oryza sativa
2 – Oryza australiensis.
HYB
44. Fig. Diplotene stage of the parents and their F 1 hybrid.
.
Oryza sativa Oryza australiensis
F 1 hybrid
45. The chromosomes of Oryza australiensis were made up partly of
heterochromatin, whereas those of sativa were mostly euchromatin.
In the F 1 hybrid of sativa × australiensis there was differential condensation
in these two morphologically different types of chromosomes.
The australiensis chromosomes with partly heterochromatin and partly
euchromatin condensed early, beginning presumably from pachynema until
diakinesis.
The sativa chromosomes started their condensation later but condensed more
completely at first metaphase.
Thus, before diakinesis, the australiensis chromosomes were stained darker
and were 2-4 times the size of the sativa chromosomes at MI-AI.
48. ANEUPLOIDY
The loss or gain of one or few chromosomes as compared to the somatic
chromosome number of a species is known as aneuploidy.
Trisomy: one chromosome extra; (2x+1). In rice, 12 primary trisomics are
possible.
Monosomy: one chromosome missing; (2x-1). In rice, 12 monosomics are
possible.
Autotriploid : three copies of same genome present; 3x.
48
49. 12 primary trisomics of Oryza sativa L. were isolated from the
progenies of spontaneous triploids and were transferred by
backcrossing to the genetic background of IR 36.
49
50. Origin of trisomics in rice
IR 262-43-8 X Khao Dawk Mali 4-2-108
In a breeding line IR 841-36-2-2 (semidwarf experimental
breeding line) a triploid plant with slight taller and
large sterile spikelets with awns was identified.
Cytological examination revealed 36 chromosomes
The plant was uprooted, pruned and divided into several
clones.
New triploid tillers X IR 22
92 seeds were obtained, 81 germinated and 72 plants survived
had 2,3,4 or 5 extra chromosomes (table1).
50
51. 2n+1 and 2n+2 are predominate in the progenies of rice triploids
studied to date, and the maximum number of extra chromosomes
tolerated by rice is 6.
Tolerance limits for extra chromosomes in rice are narrow.
51
52. 25 trisomic plants were categorized into 14 morphological groups.
4 plants of the 2n + 2 group and 2 plants of the 2n + 4 group
were planted in the greenhouse in June 1973
The progenies were again categorized into 14 distinct
trisomic lines.
11 of the 14 trisomic lines isolated were classified as primary
trisomics, and the remainder were classified as secondary trisomics.
53. Another triploid rice plant was found in 1974 in the F2 population of
IR3478.
This triploid plant was clonally propagated and pollinated with
pollen from IR3265-193-3.
The pollinations yielded a progeny of 26 plants, trisomics + 2 sterile
plants that had 2n + 1 and 2n + 2 Chromosomes.
The 2n + 1 plant was clonally propagated as the 12th primary trisomic.
After 1976, all 12 primary trisomics were transferred to IR36 background
by five backcrosses.
56. Trivalent associations of each trisomic were observed at pachytene stage.
The univalent portions were sometimes paired non homologously.
The trisomic having chromosome1 in triplicate was called triplo I, that
having an extra chromosome 2 was called triplo 2 and so on.
A small nucleolus is associated with the extra chromosome in triplo 2. In
triplo 12, in addition to the main nucleolus, several small nucleoli were
also observed. The number of these nucleoli varied from cell to cell.
61. problems facing the world’s rice geneticists and cytogeneticists,
the following areas were agreed upon as fields for increased
attention:
(1) Extensive genetic analysis of economic traits.
(2) Development of more complete linkage maps, both in indica and
japonica.
(3) Completion of a set of trisomics and a set of translocations
within a single japonica variety, within a single indica variety.
(4) Clarification of the nature of intervarietal sterility, using both
cytogenetic and genetic approaches, with special emphasis on
studies at leptotene, pachytene, and diplotene.
(5) Extension of studies of genome analysis to species in sections
other than Sativa, which is relatively complete, and the utilization
of amphidiploids.
62. (6) Clarification of species relationships still in dispute. Further
collections of African material are necessary.
(8) Preservation of genetic material used in important genetic
studies, particularly those stocks used to make comparative
genetic studies.
(10) Genetic studies on hybrid populations and on the interspecific
transfer of desirable traits qantitative characters of importance to
plant breeders.
63. Interspecific hybrids were obtained between Oryza sativa
(2x=2n=24=AA) and Oryza officinalis (2x=2n=24=CC) through an
embryo-rescue technique.
This study was undertaken to examine the possibility of establishing
MAALs having the complete chromosome complement of O. sativa
and single chromosomes from O. officinalis.
67. APPLICATION
Cytogenetic techniques are very valuable tools to get a quick
and accurate diagnosis of the possibility of gene transfer and
establishment of stable introgression.
Can rapidly be used to identify the potential progenitors of a
hybrid and the wild chromosome segments.
Used as a complement to phylogenetic studies based on gene
sequencing.
can still reveal its alien origin.
Transgenesis - documenting older events may help to discuss
the fate of a transgene eventually disseminated in the wild.