Natural occurrence and genetic diversity of Tospovirus isolates from India
Bhanupriya M1, Srinivasulu P2, Zehr UB1, Ravi KS1
1Mahyco Research Center, Jalna-Aurangabad Road, Dawalwadi, Jalna-431203, Maharashtra, India.
2Department of Virology, S.V.University, Tirupati-517502, Andhra Pradesh, India
Correspondence: Ravi.Kankanallu@mahyco.com
Tospoviruses are one of the major constraints in vegetable production next to geminiviruses in India. The spotted wilt in tomato, caused by peanut bud necrosis virus (PBNV) which is widely prevalent and it is one of the significant yield-limiting factors. Surveys were conducted during 2002每05 in the potential vegetable growing regions of Maharashtra, Andhra Pradesh, Karnataka and Tamil Nadu for the detection of tospoviruses and their natural occurrence. The incidence of spotted wilt in tomato varied from 2 to 87%. Field isolates showing typical spotted wilt and related symptoms was detected by DAC-ELISA using PBNV specific antisera, some of the hosts include tomato, chili, brinjal, peanut, greengram, soybean, blackgram, carrot, field bean and watermelon. In order to establish the genetic diversity among tospovirus isolates, the representative virus isolates were initially purified in cowpea cv. C-152 and characterized the NP gene sequences. Molecular analysis showed that the NP gene sequences from 36 isolates among nine different crops revealed very high degree of homology ie 94每99% at nucleotide and 94.9每100% at amino acid level with the reference Indian PBNV sequence (U27809). The characterized PBNV isolates were also compared with the other tospovirus members which include watermelon bud necrosis virus (WBNV) and watermelon silver mottle virus, which shares 79.8每81.3% and 83.7每87.3% homology at nucleotide & amino acid level respectively. In addition to PBNV, three other distinct tospoviruses viz., WBNV, IYSV and peanut yellow spot virus isolates were encountered in watermelon, onion and peanut crops respectively.
