Abstract
Cotton leaf curl disease (CLCuD), a major threat to the cotton industry, has a complex. etiology, Despite the identification and involvement of Cotton leaf curl virus (CLCuV, genus Begomovirus) and additional different satellite DNA molecules termed as DNA 8 and DNA 1 with CLCuD, the precise causative agents appear to be unclear. A cotton plant (Gossypium hirsutum) exhibiting symptoms of CLCuD was collected from Punjab and investigated for the presence of CLCuV in its hosts and vector. It was transmissible through whitefly (Bemisia tabaci) causing CLCuD symptoms in cotton. Employing begomovirus-specific primers located in the conserved regions of the coat protein gene, total DNA isolated from infected tissues of cotton leaf was subjected to PCR. It yielded a DNA fragment of about 550 base pairs, which was cloned and sequenced. In multiple sequence alignment with other CLCuV isolates, it revealed up to 99% nucleotide sequence identity in the corresponding regions. PCR and Southern hybridization assays were applied to monitor CLCuV in its hosts and to study transmission characteristics. A time course experiment demonstrated the presence of CLCuV in its alternate host (Lycopersicon esculentum), 12 days before the appearance of symptoms. Further, it could be detected in a single whitefly vector. Transmission studies showed that CLCuV could be acquired by whitefly within 4 h and was transmitted to test plant (Nicotiana benthamiana) within 1 hr of feeding. Two whiteflies were sufficient to induce symptoms. This study will. help in understanding the epidemiology of CLCuV and designing effective management strategies to control this devastating disease of national importance.