Inheritance of Resistance to Mungbean Yellow Mosaic Virus (MYMV) in Inter and Intra
Specific Crosses of Mungbean (Vigna radiata) 1925
heritance of resistance to MYMV disease is useful in
breeding for resistant cultivars. Inheritance of resistance
to MYMV in mungbean has been studied extensively us-
ing different resistant sources but results were contradic-
tory. Inheritance of MYMV resistance studies revealed
that the resistance is controlled by a single recessive gene
[4-9], dominant gene [10], two recessive genes [11-13]
and complementary recessive genes [14]. Thus a more
extensive study is needed in order to finalize th e mode of
inheritance of the resistance. Meanwhile understanding
the inheritance of resistance to MYMV is of prime im-
portance in mungbean breeding programmes. However
sources of resistance to MYMV are very rare in the
germplasm of mungbean, whereas a high proportion of
Ricebean (Vigna umbellata) and urdbean (Vigna mungo)
lines resistant to MYMV are available. Monika et al. and
Pandiyan et al. [15,16] reported that Ricebean (Vigna um-
bellata) contains desirable genes for MYMV resistance.
Therefore, the present study was undertaken to investi-
gate the inheritance of resistance to MYMV in inter and
intra specific crosses of mungbean.
2. Materials and Methods
Materials for the present investigation comprised a
MYMV resistant mungbean line KMG 189 and ricebean
line TNAU RED, Two MYMV susceptible mungbean
lines VBN (Gg) 2 and VRM (Gg) 1 (All the lines are ori-
ginated from Tamilnadu, India), F1, F2 and F3 genera-
tion plants (derived from crossing between resistant and
susceptible parents were used in the present study. The
field experiment was conducted during the period of
2006-2010 in every kharif and summer season of the year
at the National Pulse Research Centre. The plants were
maintained properly by providing row to row and plant to
plant spacing at 50 cm and 10 cm, respectively. The in-
fector row method, where in two test rows alternating
with spreader rows of the susceptible variety (C0 5 mung-
bean) were sown, was adopted in the field condition, for
the evaluation of MYMV infestation. No insecticide was
sprayed in order to maintain the natural whitefly popula-
tion in experimental field. Only after 80% of plants
showed MYMV incidence, the scoring of the test materi-
als was done. The rating scale suggested by Singh et al.,
[17] was adopted. The mean disease score was calculated
as disease rating and frequency per total number of plants
was also calculated. Based upon the MYMY score, the
mungbean plants were divided into five categories, resis-
tant (R), moderately resistant (MR), moderately suscep-
tible (MS), susceptible (S) and highly susceptible (HS).
Plants that are moderately susceptible (MS), susceptible
(S) and highly su sceptible (HS) were included in suscep -
tible group and resistant (R), moderately resistant (MR)
plants were included in resistant group. The chi-square
test was performed to determine the goodness of fit of
observed segregation for MYMV disease reaction in F2
and F3 generati o ns.
3. Results and Discussion
Mungbean yellow mosaic virus (MYMV) is widespread
in the major mungbean-growing areas in India. A severe
outbreak of MYMV in the southern and northern states is
currently causing serious concern to mungbean growers
and to the mungbean industry in these regions. Resis-
tance to MYMV was determined by visual symptoma-
tology. Symptomless lines were assumed to be resistant.
As mungbean lines can be infected without showing
symptoms, it is possible that these are not resistant lines.
Breeding for cultivars with resistance is a commonly ac-
cepted and effective strategy for controlling the MYMV
disease and also prevent the multiplication of virus. The
knowledge of inheritance of resistance genes and role of
each gene in the development of resistance or suscepti-
bility will be very useful for the mungbean breeders to
breed MYMV-resistant varieties. The objective of this
study was to determine the inheritance of MYMV resis-
tance in inter and intra specific crosses of mungbean. In
the field condition, MYMV infection can be evaluated by
MYMV disease rating scale suggested by Singh et al.,
[17]. The susceptible parents VBN (Gg) 2, VRM (Gg) 1
and F1 plants of all two crosses showed susceptible reac-
tion (S), that is, symptoms observed on both leaves and
pods. No symptoms were observed in resistant parents
KMG 189 and TNAU RED up to maturity, and hence,
they were scored as resistant. Based on the rating scale in
all the two F2 and F3 generations, five reactions were re-
corded, resistant (R), moderately resistant (MR), moder-
ately susceptible (MS), susceptible (S) and highly sus-
ceptible (HS). F2 generation disease screening results are
presented in Table 1.
The X2 tests of the two crosses showed a good fitness
to 3 (Susceptible): 1 (Resistance) in F2 population (Ta-
ble 2) and it showed th e dominance of susceptib ility over
the resistance which indicated a monogenic inheritance
designated as MYMV. But the segregation for 3:1 in F2
[10,11,13] is totally different from the present study.
However the F3 progenies from two crosses showed
Table 1. MYMV disease screening results in F2 generation
of crosses between re sistant and susc e ptible plants.
Plant material sTotal
plants (HS) (S) (MS) (MR)(R)
TNAU RED
×
VRM(Gg)1 187 24 50 59 30 24
KMG 189
×
VBN(Gg)2 203 19 56 57 41 30
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