Investigations of Mungbean yellow Mosaic Virus (Mymv) of Mungbean (Vigna Radiata (L.) Wilezek)
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Date
2010-07
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Department of Plant pathology College of Agriculture Gujarat Agricultural Universit
Abstract
Mungbean (Vigna radiata (L.) Wilczek) is one of the
important pulse crops primarily grown for food in India. During
the survey, occurrence of Mungbean Yellow Mosaic Virus
(MYMv) in mungbean was noticed in serious proportion
causing heavy losses in Navsari, Surat and valsad districts;.
Cultivars GM-4 and K-851 were found more severely affected
at the flowering stage during summer season . Considering the
seriousness of the problem, the present investigation was
carried out on transmission and detection of virus.
Roving field surveys were under taken in and around
Navsari , Surat and Val sad districts, the total 16 locations to
find out occurrence of the Mungbean Yellow Mosaic Virus
(MYMv) during summer, 20 I O. The MYMv incidence
increases with on increase in crop stages. Crop at the first
trifoliate leaf stage was 08-12 per cent, second trifoliate leaf
stage was 16-20 per cent and before flowering stage 4 I to 55 %
incidences were reloaded and at the time of maturity stage
showed 65-76 per cent incidence of MYMv. Fields of
Sugarcane Research Station, NAU, Navsari farm were observed
periodically. Three popular varieties of mungbean viz., K-851,
GM-3 and GM-4 were sown in the field. None of the variety
showed resistance against the disease and 75 to 100 per cent
incidence was reloaded at the time of crop maturity. Among
these, K-8S1 showed cent per cent MYMV incidence.
The disease appeared in the field as small scattered
yellow to golden yellow colour flecks on the infected leaves.
These were scattered on the entire leaves and were more
concentrated near the leaf venation. The severity of the
symptoms could be seen in the newly emerging leaves, where in
case of high susceptibility, cent per cent area of the leaf turned
yellow. The symptoms could be observed on all the green
coloured aerial parts of the plants including cotyledon leaf,
trifoliate leaves, stem, petiole, flower part, pod and seeds.
Infected plant remained stunted with few pods of small size and
shrivelled seeds.
The peR based diagnostic protocol was standardized
to amplify viral DNA, six different primer pairs were used.
Presence of DNA-A and DNA-8 molecules of the virus could
be detected by the different sets of the primers. Self designed
primer pair, LM-20F + LM-20R was best and replicative.
Therefore, the same primer pair was used for the different
diagnostic and localization purpose throughout the study.
The virus was not found to be transmitted by seeds,
mechanical sap and aphid in the susceptible plants. Whitefly
(Bemisia tabaci, Gennadius) could acquire virus i~ 30 minutes
of acquisition feeding and similarly could inoculate in 30
minutes of inoculation feeding period. There was effect of
fasting on the transmission of virus. for cent percent virus
transmission, whiteflies needs 6 hours of acquisition and
inoculation feeding period.
MYMV could be detected from the sepal, standard
petal, wing petal, keel petal and androecium . However, MYMV
could not be detected from gynoecium. Among the parts of
seeds, MYMV could be detected from the pod , seed coat and
cotyledon. However, presence of MYMV could not be detected
from embryo of the seed . From the results , it is concluded that
the seeds act as a passive source of primary inoculation and
may be termed as passive transmission of the disease or virus
through seeds .
Presence of MYMV in the callus induced from the
infected cotyledon could be detected. This is the first report of
the detection of any Begomovirus from the seeds or any part of
the seeds. Further, the virus could be multiplied (cultured)
artificially in the laboratory condition.
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Citation
PAWAR DNYANESHWAR MADHUKARRAO_43782