DIVERSITY AMONG THE COAT PROTEINS OF LUTEOVIRUSES ASSOCIATED WITH CHICKPEA STUNT DISEASE IN INDIA

Chickpea stunt is an important virus disease of chickpea in the Indian subcontinent which is thought to be caused by infection with a luteov irus. Samples of diseased chickpea plants were collected from differen t chickpea growing regions of India and analysed with a panel of monoc lonal antibodies to potato leafroll, beet western yellows and barley y ellow dwarf (RPV strain) luteoviruses. The results suggested that more than one luteovirus was present in chickpea crops near ICRISAT Asia C enter, Hyderabad. Aphid transmission tests resulted in the separation of two distinct isolates from these samples. One of them (isolate L) w as more efficiently transmitted by Myzus persicae than the other (isol ate IC). Nucleotide sequence analysis of DNA obtained by reverse trans cription-polymerase chain reaction (RT/PCR) amplification revealed tha t the amino acid sequence of the coat protein of isolate L was 94% ide ntical to that of beet western yellows virus, whereas the coat protein sequence of isolate IC was 82% identical to that of isolate L and 80% identical or less to those of the coat protein of other luteoviruses. Using newly designed ''universal luteovirus primers'', a minor sequen ce variant of isolate IC, which was 96% identical to it in part of the coat protein gene, was detected in the same location during the next season. Only isolate IC could be detected in samples from other locati ons by either serological or nucleotide sequence analysis.