Quantitative trait loci (QTL) analysis and its applications in plant breedingPGS
Abstract
Many agriculturally important traits such as grain yield, protein content and relative disease resistance are controlled by many genes and are known as quantitative traits (also polygenic or complex traits). A quantitative trait depends on the cumulative actions of many genes and the environment. The genomic regions that contain genes associated with a quantitative trait are known as quantitative trait loci (QTLs). Thus, a QTL could be defined as a genomic region responsible for a part of the observed phenotypic variation for a quantitative trait. A QTL can be a single gene or a cluster of linked genes that affect the trait. The effects of individual QTLs may differ from each other and change from environment to environment. The genetics of a quantitative trait can often be deduced from the statistical analysis of several segregating populations. Recently, by using molecular markers, it is feasible to analyze quantitative traits and identify individual QTLs or genes controlling the traits of interest in breeding programs.
A new era of genomics for plant science research has opened due the complete genome sequencing projects of Arabidopsis thaliana and rice. The sequence information available in public database has highlighted the need to develop genome scale reverse genetic strategies for functional analysis (Till et al., 2003). As most of the phenotypes are obscure, the forward genetics can hardly meet the demand of a high throughput and large-scale survey of gene functions. Targeting Induced Local Lesions in Genome TILLING is a general reverse genetic technique that combines chemical mutagenesis with PCR based screening to identity point mutations in regions of interest (McCallum et al., 2000). This strategy works with a mismatch-specific endonuclease to detect induced or natural DNA polymorphisms in genes of interest. A newly developed general reverse genetic strategy helps to locate an allelic series of induced point mutations in genes of interest. It allows the rapid and inexpensive detection of induced point mutations in populations of physically or chemically mutagenized individuals. To create an induced population with the use of physical/chemical mutagens is the first prerequisite for TILLING approach. Most of the plant species are compatible with this technique due to their self-fertilized nature and the seeds produced by these plants can be stored for long periods of time (Borevitz et al., 2003). The seeds are treated with mutagens and raised to harvest M1 plants, which are consequently, self-fertilized to raise the M2 population. DNA extracted from M2 plants is used in mutational screening (Colbert et al., 2001). To avoid mixing of the same mutation only one M2 plant from each M1 is used for DNA extraction (Till et al., 2007). The M3 seeds produce by selfing the M2 progeny can be well preserved for long term storage. Ethyl methane sulfonate (EMS) has been extensively used as a chemical mutagen in TILLING studies in plants to generate mutant populations, although other mutagens can be effective. EMS produces transitional mutations (G/C, A/T) by alkylating G residues which pairs with T instead of the conservative base pairing with C (Nagy et al., 2003). It is a constructive approach for users to attempt a range of chemical mutagens to assess the lethality and sterility on germinal tissue before creating large mutant populations.
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.
Quantitative trait loci (QTL) analysis and its applications in plant breedingPGS
Abstract
Many agriculturally important traits such as grain yield, protein content and relative disease resistance are controlled by many genes and are known as quantitative traits (also polygenic or complex traits). A quantitative trait depends on the cumulative actions of many genes and the environment. The genomic regions that contain genes associated with a quantitative trait are known as quantitative trait loci (QTLs). Thus, a QTL could be defined as a genomic region responsible for a part of the observed phenotypic variation for a quantitative trait. A QTL can be a single gene or a cluster of linked genes that affect the trait. The effects of individual QTLs may differ from each other and change from environment to environment. The genetics of a quantitative trait can often be deduced from the statistical analysis of several segregating populations. Recently, by using molecular markers, it is feasible to analyze quantitative traits and identify individual QTLs or genes controlling the traits of interest in breeding programs.
A new era of genomics for plant science research has opened due the complete genome sequencing projects of Arabidopsis thaliana and rice. The sequence information available in public database has highlighted the need to develop genome scale reverse genetic strategies for functional analysis (Till et al., 2003). As most of the phenotypes are obscure, the forward genetics can hardly meet the demand of a high throughput and large-scale survey of gene functions. Targeting Induced Local Lesions in Genome TILLING is a general reverse genetic technique that combines chemical mutagenesis with PCR based screening to identity point mutations in regions of interest (McCallum et al., 2000). This strategy works with a mismatch-specific endonuclease to detect induced or natural DNA polymorphisms in genes of interest. A newly developed general reverse genetic strategy helps to locate an allelic series of induced point mutations in genes of interest. It allows the rapid and inexpensive detection of induced point mutations in populations of physically or chemically mutagenized individuals. To create an induced population with the use of physical/chemical mutagens is the first prerequisite for TILLING approach. Most of the plant species are compatible with this technique due to their self-fertilized nature and the seeds produced by these plants can be stored for long periods of time (Borevitz et al., 2003). The seeds are treated with mutagens and raised to harvest M1 plants, which are consequently, self-fertilized to raise the M2 population. DNA extracted from M2 plants is used in mutational screening (Colbert et al., 2001). To avoid mixing of the same mutation only one M2 plant from each M1 is used for DNA extraction (Till et al., 2007). The M3 seeds produce by selfing the M2 progeny can be well preserved for long term storage. Ethyl methane sulfonate (EMS) has been extensively used as a chemical mutagen in TILLING studies in plants to generate mutant populations, although other mutagens can be effective. EMS produces transitional mutations (G/C, A/T) by alkylating G residues which pairs with T instead of the conservative base pairing with C (Nagy et al., 2003). It is a constructive approach for users to attempt a range of chemical mutagens to assess the lethality and sterility on germinal tissue before creating large mutant populations.
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.
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.
Molecular Breeding in Plants is an introduction to the fundamental techniques...UNIVERSITI MALAYSIA SABAH
This slide describe the process of molecular breeding in plants which involves the application of molecular markers for Marker Assisted Selection and Marker Assisted Breeding.
I would like to share this presentation file.
Some basics information regarding to molecular plant breeding, hope this help the beginner who start working in this field.
Thanks for many original source of information (mainly from slideshare.net, IRRI, CIMMYT and any paper received from professor and some over the internet)
Mutagenesis is the process by which the genetic information
of an organism is changed in a stable manner.
The term ‘mutation breeding’ has become popular as it
draws attention to deliberate efforts of breeders and
the specific techniques they have used in creating and
harnessing desired variation in developing elite breeding
lines and cultivated varieties.
Role of Marker Assisted Selection in Plant Resistance RandeepChoudhary2
Topic Role of Marker Assisted Selection in Plant Resistance is described in detail including some case studies.
Types of markers used in genetic engineering and biotechnology are described in detail.
Marker assisted selection is a process whereby a marker (morphological, biochemical or one
based on DNA/RNA variation) is used for indirect selection of a genetic determinant of a trait
of interest. Since the first reported linkage of an agronomically important trait (a quantitative
trait locus affecting seed weight) to a simply controlled gene (seed colour) in common bean by
Sax (1923), it has taken more than 60 years for genetic markers to become a qualified tool for
plant breeding programs. In rice, the Xieyou 218 hybrid was the first to be developed through
MAS to select individuals carrying a bacterial blight-resistant gene. Marker-assisted selection
(MAS) can be applied at the seedling stage, with high precision and reductions in cost. Genetic
mapping of major genes and quantitative traits loci (QTLs) for agricultural traits is increasing
the integration of biotechnology with the conventional breeding process. Traits related to
disease resistance to pathogens and to the quality of some crop products are offering some
important examples of a possible routinary application of MAS. For more complex traits, like
yield and abiotic stress tolerance, a number of constraints have severe limitations on an efficient
utilization of MAS in plant breeding. However, the economic and biological constraints such
as a low return of investment in small-grain cereal breeding, lack of diagnostic markers, and
the prevalence of QTL-background effects hinder the broad implementation of MAS but over
the past 2 decades, a number of R-genes conferring resistance to a diverse range of pathogens
have been mapped in many crops using molecular markers.
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.
Molecular Breeding in Plants is an introduction to the fundamental techniques...UNIVERSITI MALAYSIA SABAH
This slide describe the process of molecular breeding in plants which involves the application of molecular markers for Marker Assisted Selection and Marker Assisted Breeding.
I would like to share this presentation file.
Some basics information regarding to molecular plant breeding, hope this help the beginner who start working in this field.
Thanks for many original source of information (mainly from slideshare.net, IRRI, CIMMYT and any paper received from professor and some over the internet)
Mutagenesis is the process by which the genetic information
of an organism is changed in a stable manner.
The term ‘mutation breeding’ has become popular as it
draws attention to deliberate efforts of breeders and
the specific techniques they have used in creating and
harnessing desired variation in developing elite breeding
lines and cultivated varieties.
Role of Marker Assisted Selection in Plant Resistance RandeepChoudhary2
Topic Role of Marker Assisted Selection in Plant Resistance is described in detail including some case studies.
Types of markers used in genetic engineering and biotechnology are described in detail.
Marker assisted selection is a process whereby a marker (morphological, biochemical or one
based on DNA/RNA variation) is used for indirect selection of a genetic determinant of a trait
of interest. Since the first reported linkage of an agronomically important trait (a quantitative
trait locus affecting seed weight) to a simply controlled gene (seed colour) in common bean by
Sax (1923), it has taken more than 60 years for genetic markers to become a qualified tool for
plant breeding programs. In rice, the Xieyou 218 hybrid was the first to be developed through
MAS to select individuals carrying a bacterial blight-resistant gene. Marker-assisted selection
(MAS) can be applied at the seedling stage, with high precision and reductions in cost. Genetic
mapping of major genes and quantitative traits loci (QTLs) for agricultural traits is increasing
the integration of biotechnology with the conventional breeding process. Traits related to
disease resistance to pathogens and to the quality of some crop products are offering some
important examples of a possible routinary application of MAS. For more complex traits, like
yield and abiotic stress tolerance, a number of constraints have severe limitations on an efficient
utilization of MAS in plant breeding. However, the economic and biological constraints such
as a low return of investment in small-grain cereal breeding, lack of diagnostic markers, and
the prevalence of QTL-background effects hinder the broad implementation of MAS but over
the past 2 decades, a number of R-genes conferring resistance to a diverse range of pathogens
have been mapped in many crops using molecular markers.
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.
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
A genetic marker is a gene or DNA sequence with a known location on a chromosome and associated with a particular gene or trait. It can be described as a variation, which may arise due to mutation or alteration in the genomic loci that can be observed. A genetic marker may be a short DNA sequence, such as a sequence surrounding a single base-pair change (single nucleotide polymorphism, SNP), or a long one, like mini & microsatellites.
Molecular Markers and Their Application in Animal Breed.pptxTrilokMandal2
Molecular markers have had a significant impact on breed development and conservation efforts, transforming genetics and offering vital insights into genetic diversity, lineage tracing, and genotype characterization. The importance of molecular markers in improving genetic gains, facilitating breeding programs, and preserving genetic diversity for the long-term sustainability of the animal population has been underlined in this review paper. Emerging advancements in molecular marker technology show enormous potential for improving and conserving breeds. Deeper insights into the genetic basis of complex traits will be provided through GWAS, CRISPR/Cas9, gene editing technologies, and sequencing technologies, resulting in faster genetic gains. Breeders and conservationists will be able to make more informed judgments thanks to these technologies. In conclusion, molecular markers have had a significant impact on breed conservation and enhancement. Their innovations have changed the industry and given both conservationists and breeders vital knowledge. We can pave the road for more effective and sustainable genetic improvement and the preservation of biodiversity for future generations by combining the power of molecular markers with conventional breeding and conservation techniques.
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
Students, digital devices and success - Andreas Schleicher - 27 May 2024..pptxEduSkills OECD
Andreas Schleicher presents at the OECD webinar ‘Digital devices in schools: detrimental distraction or secret to success?’ on 27 May 2024. The presentation was based on findings from PISA 2022 results and the webinar helped launch the PISA in Focus ‘Managing screen time: How to protect and equip students against distraction’ https://www.oecd-ilibrary.org/education/managing-screen-time_7c225af4-en and the OECD Education Policy Perspective ‘Students, digital devices and success’ can be found here - https://oe.cd/il/5yV
1. SEMINAR ON
APPLICATIONOF MOLECULAR MARKERS IN PLANT BREEDING
PRESENTED BY
SUNIL.L
Reg .No:K-19/061
Research guide SEMINAR INCHARGE
Dr. M. S. Mote Dr.A.G.Bhoite
Asst. Prof. of Agril ,Botany Asso.Prof.of Agril, Botany
Division of Agril, Botany Division of Agril, Botany
RCSM College of Agriculture, Kolhapur RCSM College of Agriculture ,Kolhapur
2. What is a marker
Classification of markers
Types of molecular /DNA marker
Application of molecular markers
Case study
Conclusion
Future thrust
CONTENTS
4. What is a Marker ???
Any genetic element (locus,allele or DNA sequence) which
can be readily detected by phenotype ,cytological or
molecular techniques and whose inheritance can be easily
followed.
6. Morphological markers
Disadvantage:
• low polymorphism
• Generally dominant
• Limited in number
• Unstable to environmental
effect
Markers that are related to shape, size, colour, and surface of
various plant parts. Such characters are used for varietal
identification.
7. Cytological markers
Markers that are related with variations present in the
numbers, banding patterns, size, shape, order and position of
chromosomes are known as cytological markers.
Disadvantage: low polymorphism and need special technique
8. Biochemical markers
• Markers that related to variations in protein and amino acid
banding pattern are known as biochemical markers.
• These are detected by electrophoresis and specific staining.
• Disadvantages: limited in
number, and are influenced
by environmental factors or
the developmental stage of
the plant (Winter & Kahl,
1995).
9. DNA/Molecular markers
• The DNA markers are related to variation in genomic DNA
sequences of different individuals.
• They are based on naturally occurring polymorphism in DNA
sequence i.e. base pair addition, deletion, substitution.
• DNA markers are unlimited in number and are not affected
by environmental factors and the developmental stage of the
plant(Winter&Kahl,1995).
• These markers are selectively neutral because they are usually
located in non-coding regions of DNA.
10. • Markers that are close together or tightly-linked will be
transmitted together from parent to progeny more frequently.
• markers that are located in close proximity to genes
(i.e.tightly linked) may be referred as gene‘tags’.
• They are used to flag the position of a particular gene or trait
of interest.
11.
12. Co-dominant marker
• It indicate or differentiate
whether individual is
homozygous and
heterozyous
• Ex: RFLP,SSR
Dominant marker
• It does not differentiate
• Ex:AFLP,RAPD
13. Restriction Fragment Length Polymorphism (RFLP)
• It refers to variations found within a species in the length of DNA fragment
generated by specific endonuclease.
Advantages :
• Simple technique
• Co dominant
• highly reproducible
disadvantages:
• Requires large quantities of high
molecular weight DNA.
• Expensive, time consuming and
labor intensive .
Uses:
• Used in determining paternity
cases.
• Diagnosis of pathogen in plants.
• gene mapping ,germplasm
characterization.
14. Randomly Amplified Polymorphic DNA (RAPD)
• RAPD refers to variations found within a species in the randomly amplified
fragments of DNA generated by using a single oligonucleotide as a primer of
arbitrary sequence.
Advantages
• Simple and quick technique
• Primers are readily available
• very small DNA samples required
Disadvantages:
• polymorphism is limited
• dominant marker
• Reproducibility of results is low or
inconsistent
Uses:
• used for DNA fingerprinting of
cultivars
• Varietal identification ,construction of
linkage maps
15. Amplified Fragment Length Polymorphism (AFLP)
advantages:
• Requires small quantities of DNA
• highly reproducible
• Less labour intensive and faster
technique
disadvantages:
• Dominant markers
• Requires very high quality DNA
Uses:
• Used in germplasm characterization
• Varietal identification and MAS
• It refers to variations observed within a species in the length of amplified DNA
fragments made by restriction endonuclease.
• AFLP shares features of both RFLP and RAPD . it uses restriction enzyme
digested genomic DNA as template for PCR amplification.
16. Simple Sequence Repeat(SSR)
• SSR markers are microsatellite based markers analysed by PCR
amplification of a short genomic region containing the repeated sequence.
Advantages :
• Co-dominant
• Highly polymorphic
• Requires very small amounts of DNA
Disadvantages:
• The cost of developing SSR markers is
very high
• labour intensive
Uses:
• Used for genetic mapping of
eukaryotes.
20. Marker assisted selection(MAS)
• MAS is an indirect selection for trait of interest(gene)based on
molecular markers linked to that trait of interest .
(Or)
• Selection for specific gene (which affect a trait of interest)
using genetic markers is referred as MAS
• Marker-assisted selection may greatly increase the efficiency
and effectiveness in plant breeding compared to conventional
breeding methods (Witcombe &Virk, 2001).
• MAS is done with the help of molecular markers or molecular
techniques Example: RFLP, SSR,RAPD,CAPS,SSCP, SNP etc.
21.
22. Advantages of MAS :
• Simpler than phenotypic screening especially in the case of
complex traits.
• High efficiency( screening of progeny in early stage allows a
breeder to reject undesirable genotypes from the programme
more quickly
• Time saving (field trails ,disease test/screening)
• Selection of genotypes can be carried out at the seedling
stage
Disadvantages of MAS :
• Requires technical skill
• Expensive technique
23. Genetic diversity analysis
• Analysis of genetic diversity is important for determination of
phylogenetic relationships among the lines.
• Molecular markers can be used for assessment of genetic
diversity in cultivars.
• Generally diversity analysis is based on phenotypes of number
of characters. but phenotypic variation is expected to reflect
only a part of the variation present at the genotypic level.
• Molecular markers may be expected to capture the genetic
variation more effectively than the trait phenotypes.
24. Germplasm characterisation and conservation
• Molecular markers can be gainfully used in the different
activities of germplasm conservation
• The germplasm accessions of a crop species may be
genotyped for a set of molecular markers
• The marker data can be used for grouping of the accessions
• Marker genotype data would allow identification and removal
of duplications in the collection ,which would reduce the cost
of managing the collection.
25. Identification of varieties and hybrids
• Molecular markers genotypes can be used to develop DNA
fingerprints of different individuals /lines/varieties/hybrids.
• SSR markers are widely used for DNA fingerprinting.
• Marker data helps in
unequivocal
identification of
different varieties and
hybrids ,and can be
useful for registration of
varieties by serving as a
tools for their
identification.
26. Determination of genetic purity
• Molecular markers provide the sensitive and comprehensive
test for cultivar purity.
• Marker data of DNA is extracted from individual seedlings
used in the detection/ identification of given variety from
other contaminated variety/hybrids/weeds.
27. Gene pyramiding
• Combining two or more different genes conferring
resistance to the pathogen/insect in the single lines/variety.
• Pyramiding is extremely difficult to achieve using
conventional methods( because it requires progeny test
,repeated disease tests)
• The use of molecular markers greatly facilitates gene
pyramiding as it minimize the need for disease tests and
progeny tests.
28. F2
AB Ab aB ab
AB AABB AABb AaBB AaBb
Ab AABb AAbb AaBb Aabb
aB AaBB AaBb aaBB aaBb
ab AaBb Aabb aaBb aabb
F2
F1
Gene A + B
P1
Gene A
x P2
Gene B
MAS
Select F2 plants that have Gene
A and Gene B
Genotypes
P1: AAbb P2: aaBB
F1: AaBb
• Process of combining several genes, usually from 2 different parents,
together into a single genotype
x
Breeding plan
30. CASE STUDY -1
objectives :
• To quantify the genetic divergence of aromatic rice accessions using SSR
markers and
• to identify the potential accessions for introgression into the rice breeding
program.
Material and methods:
• This research was carried out to study the genetic diversity among the 50
aromatic rice accessions including three local check varieties using the 32
simple sequence repeat (SSR) markers.
• Seeds of the 53 rice accessions were sown in the different pots using
randomized complete block design (RCBD) with three replications.
31.
32. • The dendrogram based on UPGMA and Nei’s genetic distance
classified the 53 rice accessions into 10 clusters.
• Analysis of molecular variance (AMOVA) revealed that 89% of
the total variation observed in this germplasm came from
within the populations, while 11% of the variation emanated
among the populations.
• Using all these criteria and indices, seven accessions
(Acc9993, Acc6288, Acc6893, Acc7580, Acc6009, Acc9956,
and Acc11816) from three populations have been identified
and selected for further evaluation before introgression into
the breeding program and for future aromatic rice varietal
development.
33. CASE STUDY -2
Objective:
• To identify the pure hybrid or confirmation of hybridity in sunflower
hybrids
• To identify the specific marker associated with each hybrid and
parental lines.
Material and methods :
• The study included five hybrids, four female lines and two male
lines( which are listed in table 1)
34. • 58 primer pairs SSR markers were screened to identify the
specific marker associated with each hybrid and parental
lines.
• Among the five hybrids studied, hybrids KBSH-44 and KBSH-
53 could be distinguishable from their parental lines using a
specific SSR marker.
35. • Based on the complementary banding patterns between the
hybrids and their parents, the SSR marker ORS 309 and ORS
170 was identified as the two specific markers distinguish F1
hybrid KBSH-44 form their parental lines.
36. Similarly, hybrid of sunflower KBSH-53, could be identified and
distinguished from their parental lines by the SSR marker ORS 811
37. CASE STUDY-3
Objectives:
• This study is to develop wheat lines with inbuilt tolerance to
drought stress using marker assisted backcross breeding (MABB)
approach employing three linked quantitative trait loci (QTLs).
Material and methods:
• The high-yielding wheat cultivar ‘HD2733’ sensitive to drought and
is used as the recurrent parent.
• ‘HI1500’ released for water-limiting conditions and carrying
drought-tolerant QTLs (Xbarc68-101+ Xgdm93+ Xgwm165) was
used as donor parent.
38.
39. Grain yield in five improved lines of ‘HD2733’
• The three QTLs combined through MABC led to the development of
29 improved lines that are tolerant to drought stress.
• The improved lines have desirable morpho-physiological characters,
in tandem with high chlorophyll content, low canopy temperature,
high normalized difference vegetation index and at par grain yield
compared to the original parent ‘HD2733’.
• Out of 29 lines five drought stress-tolerant lines selected to be the
future products for release as new improved wheat cultivars.
40. FUTURE THRUST
• With the highly advanced molecular genetic techniques, we
are still not achieving our goals due to inaccurate
phenotyping.
• High-throughput phenotyping techniques solve these
problems.
• There is a need to make the molecular marker technology
more precise, productive and cost effective in order to
investigate the underlying biology of various traits of interest.
Markers themselves donot affect the phenotype of the trait of interest because they are located only near or ‘linked’ to genes controlling the trait.
It is generated by the presence and absence of recongnition site for the same restriction endonuclease in the same region of a chromosome from the different individuals of a species.
It is detected by using oligonucleotide (random sequence a primer) in PCR rxn,genomic dna sequences complementary to the primer detected in the gel,where don’t have complementary sequence will not detected .
Conventional method of breeding slow, with the help of markers easily detect the gene of interest
