Department of Plant Biotechnology, School of Biotechnology, Madurai Kamaraj University, Madurai-625021, 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.
Mungbean yellow mosaic virus (MYMV) is a bipartite geminivirus that causes yellow mosaic disease in blackgram, mungbean, soybean and mothbean. In view of the difficulties faced in blackgram transformation, we developed tobacco as a non-host model system to evaluate the potential applications of genetic engineering with viral and non-viral genes to control MYMV accumulation. Tobacco leaf discs replicated MYMV upon agroinoculation with the Agrobacterium tumefaciens strain Ach5 harbouring the partial dimers of both DNA A and B. Transgenic tobacco plants with MYMV genes for coat protein (CP), replication-associated protein (Rep)-sense, Rep-antisense, truncated Rep (T-Rep), nuclear shuttle protein (NSP) and movement protein (MP) were developed. Leaf discs from the transgenic tobacco plants harbouring MYMV genes were agroinoculated with the partial dimer clones of MYMV and analysed for viral DNA accumulation. Accumulation of MYMV DNA was inhibited in one transgenic plant harbouring the Rep-sense gene and in two plants harbouring the T-Rep gene. The leaf discs from the transgenic plants harbouring CP and MP genes showed higher accumulation of double-stranded viral DNA but accumulated very little single-stranded DNA of the virus. Transgenic tobacco plants expressing Agrobacterium VirE2, a nuclear-targeted single-stranded DNA binding protein, severely reduced the accumulation of MYMV DNA. Delivery of dsRNA gene of MYMV AC2 into blackgram through the inoculation of a wild-type Agrobacterium strain harbouring the dsRNA-AC2 gene brought about transient recovery from yellow mosaic disease. Our results highlight that genetic engineering with many viral and non-viral genes hold promise to control the yellow mosaic disease in blackgram and other pulses.
