Unit of Plant Virology, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi-110012, India.
Abstracts of the papers presented at the International Conference of Indian Virological Society on “Emerging and Re-emerging viral Diseases of the Tropics and Subtropics” at Indian Agricultural Research Institute, New Delhi, India, December 11–14, 2007.
Urdbean (Vigna mungo L.), an important legume crop in India, is suffering seriously from several viral diseases. Of the viruses, Mungbean yellow mosaic India virus (MYMIV), Groundnut bud necrosis virus (GBNV), Urdbean leaf crinkle virus complex (ULCV) are most important viruses causing low productivity of grains in India. Multiple and mixed infection with two or more viruses causes tremendous crop losses under natural conditions. To study the incidence of multiple and mixed infection, several number of initial varieties (IVT) and nine number of released varieties (RVT) of urdbean were shown in natural field conditions during kharif seasons of 2006 and 2007 at experimental farm in Indian Agriculture Research Institute, New Delhi. Various symptoms of yellow mosaic, bud necrosis, stem necrosis and veinal necrosis, leaf crinkle, growth stunting were observed in urdbean caused by single, multiple and mixed viral infection. Fortythree IVTs were studied, 32 of them were found to be mixed infected by MYMV+ULCV, 20 by MYMV+GBNV, 22 by ULCV+GBNV and 11 by MYMV+ULCV+GBNV with maximum incidence of 56%, 27%, 33.5% and 16.5%, respectively. Maximum incidence of 100%, 63%, and 56% in IVTs were observed by single infection of MYMV, ULCV and GBNV, respectively. All the nine RVTs tested, were found to be infected with single and mixed viruses and maximum incidence of 65.5% in cv P2056 by MYMV, 56.4% in cv T9 by ULCV, 14.5% in Urdbean cv. Pant U-35 by GBNV, 20% in cv. P2056 by MYMV+ ULCV, 3% in cv. P2056 by MYMV + GBNV, 3% in cv. LPG94 by ULCV + GBNV and 3% in cv. P2056 by MYMV + ULCV + GBNV were observed and recorded. The multiple and mixed infections were determined by biological reaction, electron microscopy (EM), serological and molecular methods. The infection of MYMV was detected by EM, white fly (Bemisia tabaci) transmission and RT-PCR, GBNV by ELISA and rub-inoculation on diagnostic host Cowpea cv. Pusa Komal and ULCV by typical leaf crinkle complex symptoms.
