© 2012 Plant Management Network.
Mixed Groundnut bud necrosis virus and Okra yellow vein mosaic virus Infection of Okra in India
Kunkalikar Suresh, Beradpatil Babasaheb, Kurulekar Meera, Rajagopalan Prem, and Anandalakshmi Radhamani, Plant-Virus Interactions Lab, Mahyco Research Center, Jalna-Aurangabad Road, Dawalwadi, Jalna, Maharashtra, India 431203
Suresh, K., Babasaheb, B., Meera, K., Prem, R., and Radhamani, A. 2012. Mixed Groundnut bud necrosis virus and Okra yellow vein mosaic virus infection of okra in India. Online. Plant Health Progress doi:10.1094/PHP-2012-1023-01-RS.
Okra [Abelmoschus esculentus (L.) Moench] is one of the commercial vegetable crops grown in India. In May 2011, okra leaf samples showing mosaic (Fig.1A), necrosis (Fig. 1B), and yellow vein mosaic symptoms were collected from commercial fields in the Nasik district of Maharashtra state. Some of these infected plants showed stunted growth and lower numbers of flowers. The samples were tested for different viruses by enzyme-linked immunosorbent assay (ELISA). Out of fifteen samples collected, three samples showed positive reaction with an antiserum (courtesy ICRISAT, India) specific to Groundnut bud necrosis virus (GBNV) in direct antigen-coated plate (DAC) ELISA. Further, all fifteen samples showed positive reaction to an antiserum (courtesy IISc, Banglore) specific to geminiviruses in double antibody sandwich ELISA. Whitefly transmission of the virus from these fifteen samples to five Okra seedlings each produced symptoms typical of Okra yellow vein mosaic virus (OYVMV). Mechanical inoculation with sap extracts from GBNV-positive samples produced chlorotic lesions in five each of cowpea cv. C152 (Vigna unguiculata) and indicator host Nicotiana benthamiana, which reacted positive to GBNV in DAC-ELISA. Reverse transcription (RT)-PCR was conducted to further identify the virus in samples positive for GBNV in ELISA. A DNA fragment of approximately 850 bp was amplified using degenerate primers to the nucleocapsid (N) gene, which amplifies WBNV and GBNV (MhPVIL.F 5′-ATGCCATGGCAATGTCTAMCGTYAAGCAACT-3′ and MhPVIL.R 5′-CCGCTCGAGCAMTTCCARMGAAGKRCYAG-3′) (2). Direct sequencing of the amplicon (GenBank Accession no. JX524556) revealed a nucleotide sequence identity ranging from 97 to 99% with isolates from India (GenBank Accession nos. FJ168032, EU373779, and GQ844884). The phylogenetic analysis of the N protein sequences showed that the okra isolate from India formed a cluster with those from India. To our knowledge, this is the first report of GBNV (Genus Tospovirus) infection in okra and also its mixed infection with OYVMV (Genus Geminivirus) in India. It appears that the GBNV is expanding its host range from Fabaceae (1) and Solanaceae families to crops belonging to Malvaceae family. The potential impact of mixed infection of GBNV and OYVMV on economical yield in okra warrants continuous monitoring of the diseases in field.
1. Jain, R. K., Bag, S., Umamaheswaran, K., and Mandal, B. 2007. Natural infection by tospoviruses of cucurbitaceous and fabaceous vegetable crops in India. J. Phytopathol. 155:22–25.
2. Kunkalikar, S., Sudarsana, P., Rajagopalan, P., Zehr, U. B., Naidu, R. A., and Kankanallu, R. S. 2007. First report of Capsicum chlorosis virus in tomato in India. Online. Plant Health Progress doi:10.1094/PHP-2007-1204-01-BR.