Study of betasatellite molecule from leaf curl disease of sunn hemp (Crotalaria juncea) in India

Leaves of sunn hemp (Crotalaria juncea) showing geminiviral symptoms were collected from Lucknow, India during rainy season in 2008. DNA template isolated from the symptomatic leaf tissues were subjected to polymerase chain reaction (PCR) using specific primers to amplify coat protein (CP) gene of DNA-A as well as betasatellite DNA associated with the leaf curl disease. CP gene showed 97% sequence identity with that of Cotton leaf curl Burewala virus (CLCuBwV). Further, the betasatellite DNA molecule revealed sequence similarity with previously characterized betasatellite DNA of begomoviruses affecting malvaceous crops from different regions of India and Pakistan. Maximum similarity (>90%) of betasatellite DNA under study was observed with Cotton leaf curl Multan betasatellite (CLCuMB-[Pak: Mul17:08) and other betasatellite DNA from Pakistan thus confirming possible infection of C. juncea with begomovirus. A complementary sense open reading frame (ORF) βC1 is present at nucleotide position 194–550. Sequence comparison of this ORF with other members of begomoviruses further confirmed association of a begomovirus with C. juncea. The betasatellite DNA when expressed under the control of CaMV35S promoter Nicotiana tabacum, showed leaf deformities. Our results demonstrated that a malvaceous betasatellite is adapted by a nonmalvaceous host and causes similar disease symptoms.