Mungbean Yellow Mosaic Virus in the AVRDC Mungbean ...

Workshop on Mungbean 163
Table 2. Mungbean germplasm with reported vector resistance
Vector resistant/ tolerant line References
G 65 Chhabra et al. 1979, 1980, 1981,
IM 170 1988, Chhabra and Kooner 1980,
LM 47, 141, 170, 364 Kooner et al. 1973, 1977, 1979,
M 170 Singh 1988
ML 1,3,5,6,7,15,24, 186, 192, 194, 195,
197, 235, 337, 423, 428, 711
P 131, 242, 290, 292, 293, 325, 364
T44
191-1, 10866, 11148, 15127
2. Resistance screening has been conducted in the field, under natural epidemic
conditions, using alternating rows of highly susceptible varieties.
Occasionally field screening has been supported by the release of viruliferous
whiteflies (Varma et al. 1992).
3. A positive correlation exists between whitefly populations and disease
incidence in the field (Patel and Srivastava 1990).
4. A number of agronomically acceptable cultivars have been released with
various levels of resistance. However, due to various disease rating systems
used by breeders, the term "resistance" has been used to refer to absence of
symptoms, low disease incidence, or delayed infection.
5. In most cases resistance has been confirmed in multilocational tests
conducted for several years. However, variation in the incidence between
locations and years has been observed occasionally. The presence of
strains or variants of the virus, or possibly even the involvement of
distinct viruses, has been suggested.
6. In the absence of effective diagnostic tools, it has not been possible to confirm
the presence of strains of this virus.
A set of recommendations has been formulated by the participants of this
workshop:
1. Address the MYMV problem by a cooperative regional network with AVRDC
as the coordinating body.
2. Intensify virus/vector studies on the following aspects:
a. exact geographic distribution of the virus
b. variability of MYMV and relationship of MYMV with known
geminiviruses affecting other leguminous crops
c. role of biotypes of the vector
d. information exchange