Mahyco Research Center, Jalna-Aurangabad Road, Dawalwadi, Jalna-431203, Maharashtra.
Abstracts of the papers presented at the 16th Annual Convention and International Symposium of Indian Virological Society on “Management of Vector-Borne Viruses” at International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru-502324, Hyderabad, India, February 7–10, 2006.
The cotton Leaf curl disease has emerged as a serious threat to cotton cultivation in Northern India. The disease is caused by a monopartite begomovirus with DNA-A with a satellite DNA beta molecule. In the present study, an attempt was made to study the virus sequence diversity and identify the reasons for resistance breaking in cotton cultivars. A survey has been undertaken during the cropping seasons of 2002–2005 in the major cotton growing regions of Punjab, Haryana and Rajasthan. Thirty-eight representative CLCuV isolates were characterized at molecular level to look into the genetic variability among the virus isolates. PCR fragment of DNA-A of ~700 bp (common region, full length AV2 gene and partial sequences of AC1 and CP gene) were cloned and sequenced. Nucleotide sequence analysis among CLCuV isolates revealed a high degree of genetic variability. Comparative sequence analysis showed that the Indian virus isolates were closely related to CLCuKV/CLCuMV (Pakistan) and CLCuRV (India) distantly to CLCuGV from Africa. Further it has been observed that, the virus isolates collected during 2004 and 2005 cropping season were highly distinct and posses high degree of variability. The virus strains/species emerged in and around Fazilka and Abohar regions of Punjab were found to be highly virulent and possess resistance-breaking properties, wherein the so called resistant cotton hybrids viz., LHH 144, Ankur-651, RCH-134 and F- 1861 (variety) were susceptible under natural conditions. The epidemiology of newly emerged CLCuV virulent strains and or species from Punjab need to be closely monitored with reference to virulence, resistance breaking nature and geographical distribution.
