Mahyco Research Center, Jalna-Aurangabad Road, Dawalwadi, Jalna-431203, Maharashtra.
The viruses belonging to the family Geminiviridae are one of the economically important groups of plant pathogens emerging worldwide. In India, leaf curls in tomato/cotton, yellow vein mosaic in okra, yellow mottle in cucurbits, yellow mosaic in legumes and mosaic in cassava are some important diseases caused by whitefly-transmitted begomoviruses. Molecular studies at Mahyco Research Center, Jalna observed both monopartiate (DNA A) and or bipartiate (DNA A and DNA B) genomes in tomato leaf curl virus and only DNA A in CLCuV and OYVMV. In addition, a diverse set of symptom modulating single-stranded satellite DNA beta of ~1.3 kb and sub-genomic molecules of 0.5 to 0.8 kb were also found associated with the begomovirus. Mixed infections of more than one DNA A molecule was frequently encountered. Begomoviruses infecting tomato/cucurbit/chilli, okra and cotton were highly specific and distinct; however, ToLCV recombinant sequences were encountered in okra yellow vein mosaic virus isolates and vice versa. Similarly, observed tomato leaf curl or okra yellow vein mosaic virus sequences in cotton leaf curl disease from North India. This envisages natural recombination among begomoviruses in crop plants. More than one DNA beta species were observed among begomovirus, but in some cases other distinct DNA beta species was associated in tomato leaf curl virus from Maharashtra. Association of DNA beta in bipartiate begomovirus in tomato raises the concerns of functional role of BC1 and C1 genes of DNA B and DNA beta molecules respectively. In India, begomovirus complexes are expanding among the crops and geographic distribution.
