Bhadana seminar (2)

WELCOMEWELCOMETo The
Department of Genetics &Plant breeding
Sardar Vallabhbhai Patel University of Agriculture
and Technology, Modipuram, Meerut

Tuesday, April 23, 2019Tuesday, April 23, 2019 22
DOCTORAL SEMINAR -IDOCTORAL SEMINAR -I
onon
Presented by :
Department of Genetics &Plant breeding
Sardar Vallabhbhai Patel University of Agriculture
and Technology, Modipuram, Meerut
ROLEROLE OF MARKER ASSISTEDOF MARKER ASSISTED
SELECTIONSELECTION
IN CROP IMPROVEMENTIN CROP IMPROVEMENT

 Introduction
 History
 Marker and It’s type
 Molecular marker
 Classification of molecular marker
 Application of molecular marker
 Mapping population
 Mapping of gene / QTL
 Gene tagging
 Marker – assisted selection
 Procedure of MAS
 Role & Importance of MAS
 Merits & Demerits
 Achievement
 Conclusion
 References
CONTENTS
Tuesday, April 23, 2019 3

Marker Assisted Selection (MAS) is a combined product of
traditional genetics and molecular biology.
In Plant Breeding, Molecular approaches applied through the use
of two main, but entirely different strategies, each of them
expediting the process of Plant Breeding.
In the first strategy a variety of transgenic crop have been
produced that carry genes, which could not be introduced other
by any conventional methods.
 In the second strategy, molecular markers closely linked to
numerous traits of economic importance have been developed in
several crops.
Any property of an individual showing heritable variation is
referred to as character or trait. It includes morphological,
physiological and biochemical properties in plants. Plant characters
are of two types qualitative and quantitative. Those characters
which can be easily identified are referred to as marker characters.
MAS allows for the selection of genes that controls traits of
interest, such traits are colour, disease resistance, etc.

The first genetic map was developed by A.H. Sturtevant in 1913,
which consisted of 5 genes located in a linear fashion on a chromosome
of Drosophila. Since then genetic maps have been developed in several
plant species.
In 1923, Sax first reported association of a simply inherited genetic
marker with a quantitative trait in plant when he observed segregation
of seed size associated with segregation for a seed coat color marker in
beans (Phaseolus vulgaris L.).
In 1935, Rasmussen demonstrated linkage of flowering time (a
quantitative trait) in peas.
In 1970, the discovery of Restriction Endonuclease Enzyme by Smith.
In 1980, Botstein et al. used the first DNA based genetic markers were
the Restriction Fragment Length Polymorphism(RFLP) markers.
In 1983, invention of Polymerase Chain Reaction(PCR) by Kary Mullis.
In 1990, Williams et al. &Welsh, McClellan proposed the use of single
short random primers( usually 10 mers) in a polymerase chain
reaction(PCR) as a method of generating polymorphic
markers(RAPDs).
Tuesday, April 23, 2019
5

 Marker is a trait which is tightly linked to a gene,
whose inheritance could be easily detected.
 Marker is a sign post used as a reference. The
markers are generally of three types:
I. Morphological markers
II. Biochemical markers
III. DNA marker or Molecular markers
Morphological Markers :- Morphological markers
are called visible marker. We can see i.e. shape,
size, colour, etc.
Morphological markers are generally related to
qualitative traits which can be scored visually and
these differences develop by mutation.Tuesday, April 23, 2019 6

Drawback of Morphological Marker :-
 They masked the effect of recessive gene.
• Dominant in nature, exhibit Epistatic effect.
• It shows Pleiotropic effect.
• Affected by the Developmental stage of the Plant.

 Biochemical markers are based on amino acid banding
patterns. They are also known as isozyme markers and
useful for breeders.
 A gene that encodes a protein that can be extracted and
observed; for example, isozymes and storage protein.
 Common protein markers: Isozyme
Multiple forms of the same enzyme.
 Allozyme : one enzyme and one locus.
 Isozyme : one enzyme, more than one locus (gene
duplication, gene families)
Limitations :-
 Limited in number.
 Affected by the environmental conditions.
 Also affected by the developmental stage of the plants.

o DNA markers first reported during 1980s.
o A molecular marker is a DNA sequence that is readily detected
and whose inheritance can easily be monitored.
o Molecular markers leave individual differences at DNA level
and arises from mutation in DNA.
o The use of molecular markers is based on naturally occurring
DNA polymorphism, which forms the basis for designing
strategies to exploit for applied purposes.
o A marker must be polymorphic; that is, it must exist in
different forms so that chromosome carrying the mutant gene
can be distinguished from the chromosome with the normal
gene by a marker it also carries. One of the main aspects of this
technology is that linkage between molecular markers and
traits of interest can be detected in a single cross.
o Genetic markers are specific DNA sequence differences that
can be identified through Biochemical assays.

A molecular marker should have some desirable
properties.
 It must be polymorphic as it is the
polymorphism that is measured for genetic
diversity studies.
 Co dominant inheritance. The different forms
of a marker should be detectable in diploid
organisms to allow discrimination of homo
and heterozygote.
 A marker should be evenly and frequently
distributed throughout the genome.
 It should be easy, fast and cheap to detect.
 It should be reproducible.
 Absence of non-allelic interaction.

 It is applied in testing the parentage,
 Genetic mapping and tagging of genes,
 Measurement in genetic diversity,
 Phylogenetic analysis (Relationship of an Ancestry’s
analysis),
 Fingerprinting of varieties or cultivars,
 Synteny mapping (Synteny means find out the relationship
between species and genera),
 Map based cloning of genes and
 Marker assisted selection of desirable genotypes.Tuesday, April 23, 2019 11

Molecular markers are classified into two types:
 Non-PCR based (Hybridization based)
 PCR based
1. Non PCR based marker: It consist only one marker e.g.
RFLP – Restriction Fragment Length Polymorphism.
2. PCR based marker:
A- Polymorphic Marker-
I. Dominant- e.g. RAPD – Random Amplified Polymorphic DNA.
II. Co dominant- e.g.
AFLP– Amplified Fragment Length Polymorphism, (micro-satellites),
SSRP –Simple Sequence Repeat Polymorphism, etc.
B- Monomorphic Marker

RFLP – Restriction Fragment Length Polymorphism,
AFLP –Amplified Fragment Length Polymorphism
(micro-satellites),
RAPD –Random Amplified Polymorphic DNA,
CAPS -Cleaved Amplified Polymorphic Sequence,
SSRP –Simple Sequence Repeat Polymorphism,
SNPs -Single Nucleotide Repeats,
AP.PCR – Arbitrarily Primed PCR,
DFP -DNA Fingerprinting,
STS – Sequence Target Sites,
SCARs – Seq. Characterized Amplified Region and
STMs – Seq. Target Micro-satellites.

RFLP firstly given by Botstein (1980).
It is first molecular marker, it was first technology
that enable the detection of polymorphism at DNA
sequence level and this variation at the DNA level is
the real causes of genetic diversity in the species. Main
features of this technique are:
 It is widely used for genetic mapping.
 Universal, neutral, abundant & co-dominant in nature,
 It is also used for germplasm characterization.
 Show no interlocus interaction.
 Can construct high density saturated map,
 It is effectively used for marker assisted selection in
plant breeding.

RAPD (Random amplified polymorphic DNA):-
In 1990, Williams et al. proposed the use of single
short random primers in a PCR as a method of
generating polymorphic markers RAPDs.
RAPD is based on amplification of genomic DNA with
single primer of arbitrary nucleotide sequence. This
procedure detect nucleotide sequence polymorphism in
a DNA amplification.
Advantages:
 Need for a small amount of DNA.
 It involves non radioactive assays.
 It needs a simple experimental set-up requiring only a
thermo cycler and an agarose assembly.
 It provides a quick and efficient screening for DNA
sequence based polymorphism at many loci.
 It does not involve blotting or hybridization steps.

Advantages:
 This technique is extremely sensitive.
 It has high reproducibility, rendering it superior to RAPD.
 It discriminates heterozygote's from homozygote's when a gel
scanner is used.
 It is not only a simple fingerprinting technique, but can also be
used for mapping.
Disadvantages:
 It is highly expensive and requires more DNA than is needed in
RAPD.
 It is technically more demanding than RAPDs, as it require
experience of sequencing gels.
 AFLPs are expensive to generate as silver staining, fluorescent dye,
or radioactivity detect the bands.
Amplified fragment length polymorphism
(AFLP)
Amplified fragment length polymorphism was developed
by Zabeau and Vas in 1993.This is a highly sensitive method for
detecting polymorphism throughout the genome. It is essentially
a combination of RFLP and RAPD methods.

(1) LEAF TISSUE
SAMPLING
(2) DNA EXTRACTION
(3) PCR
(4) GEL ELECTROPHORESIS
(5) MARKER ANALYSIS
Marker analysisMarker analysis
overview in fig:overview in fig:

APPLICATION OF MOLECULARAPPLICATION OF MOLECULAR
MARKERMARKER
 DNA markers can be used for map-based cloning of genes ofDNA markers can be used for map-based cloning of genes of
interest.interest.
 DNA markers have been used to map quantitative trait lociDNA markers have been used to map quantitative trait loci
(QTLs).(QTLs).
 DNA markers can be used for indirect selection of difficultDNA markers can be used for indirect selection of difficult
traits like yield etc; this is known as marker-assistedtraits like yield etc; this is known as marker-assisted
selection.selection.
 DNA marker can be used for rapid and unequivocalDNA marker can be used for rapid and unequivocal
diagnosis of human disease.diagnosis of human disease.
 DNA marker can be used for assessment of geneticDNA marker can be used for assessment of genetic
diversity, taxonomic classification and for DNA fingerprintingdiversity, taxonomic classification and for DNA fingerprinting
used for identification of individual/varieties/parents etc.used for identification of individual/varieties/parents etc.
 Molecular markers can be used for elimination of undesirableMolecular markers can be used for elimination of undesirable
genes, in segregating population.genes, in segregating population.
 The molecular markers that are uniformly distributedThe molecular markers that are uniformly distributed
throughout the genome can be used to estimate the geneticthroughout the genome can be used to estimate the genetic
contribution of each parent to each individual of acontribution of each parent to each individual of a
segregating population.segregating population.

MAPPING POPULATIONMAPPING POPULATION
The breeding population which is used forThe breeding population which is used for
identification, tagging and mapping of gene/QTLidentification, tagging and mapping of gene/QTL
is known as mapping population. The mappingis known as mapping population. The mapping
population may be Fpopulation may be F22, B, BCC, RILs, NILs, DH Lines., RILs, NILs, DH Lines.
RILs is also called F2- derived lines, are homozygous lines
derived from individual F2 plants from a suitable cross. RILs
provides an excellent mapping strategy and a permanent mapping
source. RILs are created by single-seed descent (SSD) from F2
plants through at least five or more generations of continued
selfing. This process yield a set of lines each of which contain a
different combination of linkage blocks from the original parents.
RILs is ideal for QTL mapping.
RILs (Recombinant inbred lines)

NILs (Near isogenic lines)
Near-isogenic lines are those lines that are identical
in their genotype, except for one gene. In this
programme, a donor parent (DP) which is
homozygous for the allele of interest, is crossed with a
recurrent parent (RP) which is homozygous for the
wild type or standard allele of this locus. The resultant
F1 individual backcrossed (BC) to the RP to obtain BC
generation. In each BC generation, only those BC
individuals that have the introgressed allele and
which are most similar to the RP in phenotype are
selectively crossed with the RP. The NILs have been
developed in many crop sps. by the method of
backcrossing.

RR X rr
Resistant Susceptible
(Donor parent) (Recurrent parent)
F1 Rr X rr
(Resistant) (RP)
(Backcross)
BC1 rr X Rr, rr
(RP) (Rejected)
BC
BC6 Rr, rr
(Rejected)
Selfed
RR, Rr, rr
(Rejected) Selfed
Resistant Susceptible
Progenies progenies
(Near isogenic lines)

P1 X P2
F1
By anther culture/microspore culture
Haploid plant
Double haploid
Colchicine
Endomitosis
Double haploid or DH Lines :
The term haploid refer to those plant which possess a
gametic chromosome number. DH is used for the
production of homozygous plant having DNA sequence
of the donor parent. DH is used as mapping population
for mapping and tagging of the gene/QTLs.

The gene mapping is a technique which is used to identify genes
responsible for expression of specific traits. Quantitative trait locus is
refer to a chromosomal region that is control quantitative trait. The
QTL mapping refers to locating of genes that control expression of
quantitative traits or used to identify where QTLs are located on the
chromosome. The important mapping technique are fallows:
I. Single Marker analysis,
II. Interval mapping,
III. Composite interval mapping,
IV. Multiple interval mapping, and
V. Bayesian interval mapping -(Satagopan et al. 1996).
Limitations:
 Poor resolution of agronomic QTLs.
 Small effects
 Interaction with environment and genetic background.
 Expense of genotyping.
MAPPING OF GENE/QTL

An important use of DNA marker is to tag gene/QTLsAn important use of DNA marker is to tag gene/QTLs
influencing qualitative traits e.g. disease resistance. In someinfluencing qualitative traits e.g. disease resistance. In some
species, the availability of nearly isogenic lines (NILs)species, the availability of nearly isogenic lines (NILs)
facilities detection of RFLP markers linked to monogenicfacilities detection of RFLP markers linked to monogenic
disease-resistance genes. NILs are developed by repeateddisease-resistance genes. NILs are developed by repeated
backcross to the RP under continuous selection for thebackcross to the RP under continuous selection for the
resistance trait. The donor genome is thereforeresistance trait. The donor genome is therefore
progressively diluted in the introgressed lines. When theprogressively diluted in the introgressed lines. When the
parents and the NILs derived from them are compared withparents and the NILs derived from them are compared with
molecular probes, only those are linked to the resistancemolecular probes, only those are linked to the resistance
locus are expected to be polymorphic in the NILs. Thelocus are expected to be polymorphic in the NILs. The
linkage and the genetic distance between RFLP markers andlinkage and the genetic distance between RFLP markers and
the resistance locus are then verified by segregation analysisthe resistance locus are then verified by segregation analysis
in normal mapping population. This technique has beenin normal mapping population. This technique has been
successfully employed for tagging genes in several crops.successfully employed for tagging genes in several crops.
GENE TAGGINGGENE TAGGING

 Marker assisted selection (MAS) is the breeding strategy in which selection
for a gene is based on molecular markers closely linked to the gene(target
loci) of interest rather than the gene itself. MAS has become possible for
traits both governed by major genes as well as quantitative trait loci (QTLs).
 MAS refer to indirect selection for a desired plant phenotype based on the
banding patterns of linked molecular markers. Improvement of crop plants
for various economic characters using indirect selection for linked molecular
markers is referred to as molecular breeding.
 In this technique, linkages are sought between DNA markers and
agronomically important traits such as tolerance to biotic and abiotic
stresses and quality parameters . The essential requirements for MAS in a
plant breeding program are as follows:
Marker's should co segregate or be closely linked with the desirable trait.
An efficient means of screening of large populations for the molecular markers (s)
should be available.
It should be economical to use and be user friendly.MAS based on:
Morphological Markers and DNA Markers.

 Application
 High accuracy
 Rapid method
 Free from environmental effects.
 Permits gene pyramiding
 Trait improved
 Requires sophisticated laboratory
 Health hazardsTuesday, April 23, 2019 27

In the marker aided selection, RFLP markers are widely
used for genetic improvement of crop plants for various
economic characters. The marker aided selection consists of
five important steps. These are briefly discussed below:
1. Selection by parents:
The parents should be such so that we can get usable level
of polymorphism (variation) in the RFLP markers. This will
help in identification of DNA of both the parents and also
their segments in F2 generation in various recombinations. For
selection of parents, we have to screen germplasm and select
parents with distinct DNA. The parents that are used for MAS
should be pure (homozygous). In self-pollinated species,
plants are usually homozygous. In cross-pollinated species,
inbred lines are used as parents.

2. Development of Breeding Populations:
The selected parents are crossed to obtain F1 plants. F1 plants
between two pure-lines or inbred lines are homogenous but
are heterozygous for all the RFLPs of two parents involved in
the F1. The F2 progeny is required for the study of segregation
pattern of RFLPs. Generally 50-100 F2 plants are sufficient for
the study of segregation of RFLP markers.
3. Isolation of DNA:
The main advantage of MAS is that DNA can be isolated even
from the seedlings and we need not to wait for flowering or
seed development stage. The DNA is isolated from each plant
of F2 population standard procedures are available for DNA
isolation. The isolated DNA is digested with specific restriction
enzyme to obtain fragments of DNA. The DNA fragments of
different sizes are separated by subjecting the digested DNA to
agarose gel electrophoresis. The gel is stained with Ethidium
Bromide and the variation in DNA fragments can be viewed in
the ultraviolet light.

4. Scoring RFLPs:
The polymorphism in RFLPs between the parents and
their involvement in the recombinations in F2 population
is determined by using DNA probes. The labelled probes
are used to find out the fragments having similarity. The
probe will hybridize only with those segments which are
complementary in nature. Generally 32P is used for
radioactive labelling of DNA probe. In this way RFLP are
determined. Non-radioactive probe labelling techniques
are also available.
5. Correlation with morphological traits:
The plant selected with the help of molecular marker
are tested in the target environment, for their phenotypic
screening and agronomical performance. Once the
correlation of molecular markers is established with
morphological markers, MAS can be effectively used for
genetic improvement of various economic traits.

F1 x P1
P1 x P2
CONVENTIONAL BACKCROSSING
BC1
VISUAL SELECTION OF BC1 PLANTS THAT
MOST CLOSELY RESEMBLE RECURRENT
PARENT
BC2
MARKER-ASSISTED BACKCROSSING
F1 x P1
P1 x P2
BC1
USE ‘BACKGROUND’ MARKERS TO SELECT PLANTS
THAT HAVE MOST RP MARKERS AND SMALLEST %
OF DONOR GENOME
BC2

Development of Swarna sub1. The Swarna sub 1 line has been developed by
marker assisted backcross breeding, involving Swarna as recurrent parent and
FR13A as donor parent for submergence tolerance.
Swarna x FR13A
RILs
Mapping
(Map the gene sub;chr.9)
Tagging
[with the marker (M1)]
Sub 1 Chr. no. 9
(M1) of FR13A
Swarna x FR13A
F1 X Swarna

BC1
F1
Isolate the DNA from P1,P2 and BC1F1 progenies at seedling stage (21days)
Go with the PCR for obtaining the banding pattern
On the basis of banding pattern select a progeny which is identical to donor parent
BC2F1
Again repeat all the steps
upto BC4 generation
BC4F1
Selfing
BC4F2
Plants are similar to Swarna with desirable gene of FR13A
Screening for submergence tolerance
Development of Swarna sub1Tuesday, April 23, 2019 33

Marker-assisted selection has become a promising and
potent approach for integrating biotechnology with
conventional and traditional breeding. The interest of
plant breeder in molecular marker revolve around
certain points:
Resistance breeding:
Availability of tightly linked genetic markers for
resistance genes will help in identifying plants carrying
these genes simultaneously without subjecting them to
pathogen or insect attack in early generations. The breeder
would require a low amount of DNA from each individual
plant to be tested without destroying the plant, and seed
the presence or absence of the product of PCR reaction
(marker band) on the gel. Only materials in the advanced
generations would be required to be tested in disease and
insect nurseries.

 Pyramiding of major/minor genes into cultivar for
development of durable resistance/multiple
resistance: Pathogens and insects are known to
overcome resistance provided by single genes. Single-
gene resistances are fragile and often broken down
easily. Therefore, breeders intend to accumulate several
major and minor resistance genes into one cultivar to
achieve durable resistance. Durability of resistance has
been increased by developing multilines and by
pyramiding of resistance genes. MAS for resistance
genes can be useful in these approaches. Pyramiding of
bacterial blight resistance genes Xa1. Xa3, Xa4, Xa5 and
Xa10 in different combinations using molecular
markers has been reported in rice.
 Improvement of qualitative characters: RFLP markers
have been linked to the linolenic acid content Fan locus
in soybean (Brummer et al., 1995). Not only this, RAPD
markers that control somatic embryogenesis in alfalfa
have been identified.

 Molecular markers for hybrid vigor: Hybrids in crops such
as maize, sorghum, rice pearl millet, cotton, and several
vegetable crops have contributed greatly toward increasing
the yield potential of these crops. The use of molecular
markers has been investigated in maize and rice. Photoperiod
sensitive genetic male sterility (PSGMS) genes in rice,
designated pms-1 and pms-2, were located on chromosomes 7
and 2, respectively.
 Molecular markers and abiotic resistance: Using molecular
markers, biochemists and physiologists have identified
specific traits beneficial in improving drought responses such
as osmotic adjustments, water use efficiency, and efficient
root system. All these add to the yield improvement in crop
plants. In rice and maize, QTLs for root traits have been
identified and are being used to breed high yielding drought-
resistant rice and maize genotypes. In many crops, RAPD
markers are population specific. MAS has helped to improve
yield performance under drought in beans, soybean, and
peas.

Host species Pathogen Resistance gene Marker
Rice Pyricularia oryzae
Xanthomonas oryzae
Pi-2(t), Pi-4(t),
Xa 21
RFLP
Wheat Puccinia recondite
Hessian fly
Lr 9, Lr 24
H 21
RAPD
RFLP & RAPD
Maize Leaf blight Rhm RAPD
Potato Cyst nematode H1 RFLP
Barley Stem rust RPg1 RFLP

Some of the institutions working on MAS in India
for different traits of rice
Sl.
No.
Institution Variety Trait/Genes
1 IARI & NRCPB,
New Delhi
Pusa Basmati-1 Bacterial blight (xa13 and Xa
21)
2 PAU, Ludhiana PR 106 and Pusa 44 Bacterial blight
(xa5, xa13 and Xa21)
3 TNAU, Coimbatore Co 43 and ADT 38 Gall midge (Gm1 and Gm4)
4 UAS, Bangalore IR 64 Blast (Pi1 and Pi2)
5 DRR, Hyderabad Triguna and BPT 5204 Bacterial blight (xa5, xa13
and Xa21)
6 IGAU, Raipur Swarna Gall midge (Gm2 and Gm4)
7 CRRI, Cuttack IR 64, Swarna, Tapaswini
and Lalat
Bacterial blight (xa5, xa13
and Xa21)
Swarna and Lalat Gall midge (Gm1 and Gm4)
Vandana and Kalinga III Blast (Pi2 and Pi9)
Sarala, Savitri and
Gayatri
Submergence (Sub 1)

 It permits early screening of traits that are expressed late in the life
of plant. For example characters such as grain or fruit quality, flower
colour, male sterility, photoperiod sensitivity. On other words, DNA
isolated at seedling stage can throw light about the traits which are
expressed later on.
 It permits screening of traits that are extremely difficult, expensive
or time consuming to sore phenotypically. For example, screening
for traits such as root morphology, resistance to biotic (Insects,
diseases) and abiotic stresses (drought, salinity, mineral deficiencies
or toxicity) is very easy through marker aided selection.
 It helps in distinguishing the homozygous versus heterozygous
condition of many loci in a single generation without the need of
progeny testing, because molecular markers are co-dominant.
 DNA markers permits marker aided selection for several characters
at one time.
 RFLP markers help in indirect selection of recessive allele, in the
backcross programme in the heterozygous condition without selfing
or progeny testing. Thus this is a rapid method of crop
improvement.
 The accuracy of marker aided selection is very high, molecular
markers are not affected by environmental conditions.

 It requires a sophisticated and well equipped laboratory to
initiate the work on DNA markers assisted selection.
 The molecular breeding techniques are very expensive,
because these techniques require very costly equipments,
glasswares and chemicals.
 It requires well trained manpower for handling of equipments,
isolation of DNA molecule and study of DNA markers.
 The detection of various DNA markers (RFLP, AFLP, RAPD) is
a laborious and time consuming work.
 For RFLP markers, a huge breeding population has to be
screened to get meaningful results which is a very
cumbersome job. This limits the use of RFLP in plant breeding.
However, short cut methods are expected to be developed in
the future.
 Molecular breeding/MAS involves use of radioactive isotopes
on labeling of DNA, which may lead to serious health hazards.
DEMERITS

 Pyramiding of bacterial blight gene Xa5, Xa21, xa13 by Khush group, IRRI
& resistant two rice varieties developed e.g. Amgke, Conde in Indonesia.
 Development of Swarna sub-1. The Swarna sub-1 line has been developed
by marker assisted backcross breeding, involving Swarna as recurrent
parent and FR-13A as donor parent for submergence tolerance by D.J.
Mackill and group at IRRI.
 Incorporation of Saltol 1 gene in the background IR 64 under progress at
IRRI
 Marker assisted drought tolerant QTL pyramiding was done in the
background of IR64, from two donor STYH and BR24 (Dwivedi et al.,
2005).
 At IARI, Dr. N.K. Singh and group (2003) had combined bacterial blight
resistance and Basmati quality characteristics by marker assisted
backcross breeding in Pusa Basmati-1.
 MAS used in Cereals- Maize, Wheat, Barley(CYMMIT, USA, Australia,
Canada) for insect-pest resistance, protein quality and other agronomic
traits.
 MAS in INDIA: cultivars Rice(ImprovePB-1, Improved Sambha Mahsuri);
Pearl-Millet(HHB-67&67-2), Maize(Vivek-QPM9).

 MAS may have potential in population and inbred line
development. When QTLs and single genes are adequately
mapped, they can be isolated by map-based cloning strategies.
The effectiveness of any MAS will depend on the accuracy of the
phenotypic classification of trait expression and the degree of
linkage between the marker's and traits of interest.
 Marker allow interesting alleles to be traced through the
pedigrees of breeding programmes or mined out of germplasm
collections to serve as the basis for future varietals improvement.
 Molecular markers technology can benefit breeding objectives by
increasing the efficiency and reliability of selection and by
providing essential insights into how genes and QTL are
identified.
 Using Markers in combination with both QTL and association
approaches may accelerates the biotechnological innovative.

 Chawla H.S. (2010). Introduction to plant biotechnology, 3rd
Edition,
pp.356-397.
 Dwivedi et al. (2005). pyramided, 18 drought tolerant QTLs in the
genetic background of IR64, from the two donor, STYH (Chinese) and BR24
(Bangladesh).
 Kole, C. and Abbott, A. G. (eds.) 2008. Principles and practices of Plant
Genomics, Vol.1: Genome Mapping, Science Publishers, Enfield, NH, USA.
 Ren, Z.H. et al.(2005). A rice quantitative trait locus for salt tolerance
encodes a sodium transporter. Nature Genet. 37 : 1141-1146.
 Singh A.K. et al. (2003).combining bacterial blight resistance and
Basmati quality Characteristics by phenotypic and molecular marker
assisted selection in rice. Molecular breeding 00: 1-11.
 Singh S.P.,Sundaram R.M & Biradra S.K.(2006). Identification of
simple sequence repeat marker for utilizing wide compatibility gene in
inter sub specific hybrid in rice (Oryza sativa L.). Theor. Appl. Genet;
(113): 509-517.
 Singh, P. (2009) Genetics, kalyani publication pp. 255-263.
 Steele, K. A. et al. (2006). Marker assisted selection to introgress rice
QTLs controlling root traits into an Indian upland rice variety, Theory.
Appl. Genet. 112: 208-221.
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