Advanced Centre 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.
Whitefly transmitted geminiviruses in the genus Begomovirus of the family Geminiviridae caused severe leaf curl and yellow mosaic disease in economically important crop species. The genome of begomoviruses infecting crop plants in Old World and New World have been understood in the last decade. Majority of Old World begomoviruses are monopartite and have the essential coding regions organized in a single genome compoonent DNA A. All New World begomoviruses and some Old World begomoviruses are bipartite having two DNA components, DNA A and DNA B. Recently a satellite DNA b was found to be associated with large number of Old World monopartite begomoviruses and is reported to be essential for the production of characteristics symptoms in the primary host. In our study on the genomic components of begomoviruses infecting Cucurbitaceous, Solanaceous and Leguminaceous plants more than fifty per cent of the samples analysed were found to be associated with DNA A, DNA B and satellite DNA b. The study convincingly indicated association of DNA b with two biparting becomoviruses, Tomato leaf curl New Delhi virus infecting tomato, potato and cucurbits and cowpea isolate of Mungbean yellow mosaic India virus. In agro-infectivity studies involving a monopartite begomovirus Tomato leaf curl Bangalore virus and the bipartite begomovirus, the presence of DNA b component was found to enhance the replication level of DNA A and DNA B.
