MYMV tolerance in green gram

1. Welcome
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2. YMV TOLERANCE IN GREENGRAM
SPEAKER: NIDHI SINGH
CHAIRMAN: Dr. N. MANDAL
SEMINAR LEADER: Dr. N. MANDAL
DEPARTMENT OF Biotechnology, Instrumentation and
Environmental Science, FACULTY OF AGRICULTURE
2/13/2014
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3. INTRODUCTION
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4. MUNGBEAN [VIGNA RADIATA (L.) ]
1. One of the thirteen food legumes grown in India
and third most important pulse crop of India after
chickpea and pigeonpea.
2. Native to India-Burma region of South-East Asia.
It is cultivated extensively in the India-Burma-
Thailand region of Asia.
3. India covers up to 65% of the total world acreage
and 54% of total production
Chatterjee and Randhawa, 1952 4

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•Grown principally for its high protein seeds that are
used as human food
•Contains about 24 per cent protein
•Being a short duration pulse crop, it fits well in
mixtures and crop rotation
•Used as green manure crop
•Helps to enrich the soil by symbiotic relationship with
specific soil rhizobia of the genus Bradyrhizobium

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1. Cercospora leaf spot (C. canescens, C. cruenta),
2. Powdery mildew (Erysiphe polygoni),
3. Root disease complex (Pythium spp.,
4. Rhizoctonia solani, Fusarium spp.)
5. Reniform (Rotylenchulus reniformis)
6. Root knot (Meloidogyne spp.) nematodes.
o Prone to several diseases
o Harbours different viruses namely alfalfa mosaic
virus, bean common mosaic virus, cucumber
mosaic virus, leaf crinkle virus, leaf curl virus,
mosaic mottle virus and mungbean yellow mosaic
virus.

7. Among all the viruses, mungbean yellow
mosaic virus (MYMV) is the most destructive
one
First ever reported from fields of IARI, New
Delhi in 1960 and is transmitted principally by
whitefly, Bemisia tabaci (Genn.) and grafting
but not by sap, seed or soil (Nariani, 1960)
Major biotic stresses accounting for the low
harvest index and causes significant yield loss
MYMV

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Geminiviruses have been grouped into four genera:
Mastrevirus, Curtovirus, Topocuvirus and Begomovirus,
depending on their vector, host range and genomic characteristics
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MYMV belongs to the genera begomovirus of the family
Geminiviridae (Bos, 1999).
The virus has geminate particle morphology (20 x 30 nm) and
the coat protein encapsulates spherical, single stranded DNA
genome of approximately 2.8 Kb (Hull, 2004).
MYMV Genome organization
Stanley et al., 2005

9. GENETICS OF MUNGBEAN YELLOW MOSAIC
VIRUS (MYMV) IN MUNGBEAN
 single recessive gene is responsible for MYMV resistance in mung
bean
 The expression of the major gene responsible for MYMV
resistance/susceptibility was affected by modifying genes
 These modifying genes caused variation in the degree of MYMV
resistance/susceptibility in the progenies derived from a single cross
 Evolution of a highly resistant mung bean line for MYMV disease
would depend on the accumulation of favourable modifying genes.
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Khattak et al., 2000

10. SYMPTOMATOLOGY
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First symptoms appear on the young leaves in the form of mild
scattered yellow specks or spots
Next trifoliate leaf emerging from the growing apex shows irregular
yellow and green patches alternating with each other
The leaf size is generally not much affected but sometimes the green
areas are slightly raised and the leaves show slight puckering and
reduction in size.
The size of yellow areas goes on increasing in the new growth and
ultimately some of the apical leaves turn completely yellow.
The diseased plants usually mature late and bear very few flowers and
pods.
 The size of the pod is reduced and more frequently immature small
sized seeds are obtained from the pods of diseased plants.

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SURVEY
To obtain information’s on the natural incidence of Yellow
Mosaic disease (YMD) of mungbean (Vigna radiata) in the
agro-ecological condition of lateritic zone of West Bengal a
survey was conducted during the pre kharif season of 2009
in different locations of Birbhum , Bankura and Purulia
District
The natural incidence of the disease in farmers fields
incidence of YMD was varied from 5.33% to 14.00%
according to the location and variety
PAUL, 2013

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Mechanical
transmission
Graft
transmission
Insect
transmission
Transmission
Nariani et al., 1960

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Epidemiology
Murugesan and Chelliah (1977) reported a yellow
mosaic on greengram sown during March to May months.
A positive correlation of whitefly population on 20 and 30
day crop and disease incidence at 45 days old crop with
maximum temperatures was obtained.
 In most of the research regarding this aspect it has
been found that all the genotypes of mungbean showed a
higher disease incidence during summer compared to
spring and rainy season crops.

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Growth attributes and losses
Reduction of 9.6 to 38.2 per cent in height, 7 to
28.5 per cent in fresh weight of shoot and 4.3 to
22.1 per cent in dry weight, 25.7 per cent in 1000
seed weight of susceptible cultivar was observed
by Premchand and Varma (1983)
However, the germinability of seeds was
apparently unaffected due to yellow mosaic.
yield loss of 83.9 per cent and a maximum
growth reduction of 62.94 per cent in Vigna
radiata cv. Pusa baisakhi was reported by
Quaiser Ahmed (1991)

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Mode of inheritance of resistance to mungbean
yellow mosaic virus (mymv) in mungbean
The MYMV resistance was inherited through a major
recessive gene
No maternal effect was found for the inheritance of
MYMV resistance in mungbean.
The monogenic recessive inheritance for MYMV has
been reported by Singh and Patel (1977), Malik et al. (1986
& 1988).

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Screening
For the purpose of identifying
resistance/tolerance in mungbean
germplasm, screening of mungbean
genotypes for resistance and
tolerance to MYMV has to be done.
This can be achieved by
developing disease screening
nursery
Screening has to be done in
natural environmental condition.
It can also be achieved by using
agroinoculation.

17. CONSTRAINTS
 Lack of enough genetic diversity in the parental
material used narrow genetic base results in
inherently low yield potential.
 The susceptibility to biotic stresses and abiotic
stresses has become the major constraints in
achieving higher yield in this crops
 Lack of suitable varieties and genotypes with
adaptation to local conditions,
 absence of suitable ideotypes for different cropping
systems and poor harvest index have
 The disease incidence is seasonal and cannot be
created as and when desired by artificial means.
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18. DEVELOPMENT OF YMV-TOLERANT VARIETY
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Identification of resistant lines
through conventional breeding is
time consuming and requires
evaluation at ‘hot spot’ area
(Selvi et al. 2006).
Indirect selection using molecular
markers linked to MYMIV resistant
genes would facilitate precision
plant breeding and high-throughput
marker assisted selection (MAS) of
resistant genotypes.
An attempt should made
to develop molecular
marker(s) linked with the
YMV-tolerance in Vigna
mungo
The results of molecular analysis
can be relied upon only when there is
an accurate phenotypic data. This
helps to draw conclusions more
precisely by correlating the results
obtained through molecular analysis
with the phenotypic analysis.
Hence, while exploring the
genotypes for the resistant
motifs it is necessary to
screen them for diseases
under natural or artificial
conditions.

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STRATEGIES
Mapping of MYMV tolerance
genes in greengram.
Development of Yellow Mosaic Virus (YMV) resistance linked
DNA marker in Vigna mungo from populations segregating for
YMV-reaction
crosses with MYMV-tolerant mungbean
germplasm, interspecific crosses with highly MYMV-
resistant blackgram, and the use of gamma ray
mungbean mutants
Development of MYMV specific
DNA Probes
Agro-inoculation technique may lead to the
development of a MYMV resistance variety.

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Achievements

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YMV tolerant line identified in the field with in large population of the
susceptible cultivar T-9 and crossed with the T-9 and F1, F2, & F3
progenies were raised.
Different generations were phenotype for YMV tolerance reactions by forced
inoculation using viruliferous white flies monogenic recessive control of YMV-
tolerance was revealed from the F2 - segregation ratio of 3:1 susceptible :
tolerant
Of 24 pairs of resistance gene analog (RGA) primers screened, only
one pair, RGA 1F-CG/RGA 1R, was found to be polymorphic among
the parents.

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Selected F2individuals and F3 families were genotyped with the polymorphic RGA
primer pair and the polymorphism was found to be linked with YMV-reaction
This primer pair amplified a 445bp DNA fragment only from homozygous tolerant
and the heterozygous lines.
The 445bp marker band was sequenced and named ‘VMYR1’.
The predicted amino acid sequence showed highly significant homology with the NB-
ARC domain present in several gene products involved in plant disease
resistance, nematode cell death and human apoptotic signaling
This YMV-resistance linked marker is of potential commercial importance in
resistance breeding of plants.

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The present investigation was carried out to study the
inheritance and identify molecular markers linked with MYMV
resistance gene by using F1, F2 and 167 F2 : 8 recombinant
inbred lines (RILs) developed from the cross ‘TM-99-37’
(resistant) × Mulmarada (susceptible).
The F1 was susceptible, F2 segregated in 3S:1R phenotypic
ratio and RILs segregated in 1S:1R ratio in the field screening
indicating that the MYMV resistance gene is governed by a
single recessive gene.

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Of the 140 RAPD primers, 45 primers showing
polymorphism in parents were screened using bulked
segregant analysis.
 Three primers amplified specific polymorphic fragments
viz. OPB-07600, OPC-061750 and OPB-12820.
The marker OPB-07600 was more closely linked (6.8 cM)
with a MYMV resistance gene as compared to OPC-
061750 (22.8 cM) and OPB-12820 (25.2 cM).
The resistance-specific fragment OPB-07600was
cloned, sequenced and converted into a sequence-
characterized amplified region (SCAR) marker and
validated in twenty genotypes with different genetic
backgrounds.

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The present study was undertaken to identify RAPD marker
associated with Mungbean Yellow Mosaic Virus (MYMV)
resistance in mungbean ( Vigna radiata (L.) Wilczek) cross ML
267 x CO 4.
 Bulked segregant analysis was employed to identify RAPD
markers linked to MYMV resistant gene of ML 267.
 A total of 149 random decamers were surveyed for
identification of polymorphic markers between the DNA bulks
of resistant and susceptible F2 individuals and their parents

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 Forty one primers produced specific band for resistant
parent which were absent in susceptible parent.
Out of 41 random primers, three primers viz., OPT 16, OPS
7 and OPAK 19 produced specific fragments viz., OPT
16564, OPS 7900 and OPAK 19400, respectively in resistant
parent and resistant bulk, which were absent in the susceptible
parent and bulk
 Amplification of individual DNA samples out of the bulk
with putative markers, OPS 7900 only revealed polymorphism
in all 8 resistant and 6 susceptible plant, indicating that the
marker OPS 7900 was associated with MYMV resistance in ML
267.

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CONCLUSION Urgent need to
develop high-yielding
varieties with resistance
to diseases with greater
yield stability.
 Development of
tightly linked markers
endowed with the
features of resistance
gene candidates
Generating superior
genotypes with
durable YMV-
resistance.

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