Infectivity analysis of chilli leaf curl Ahmedabad virus and its associated tomato leaf curl Bangladesh betasatellite complex in chili

Abstract

Chilli leaf curl virus is responsible for inducing leaf curl disease in Chili (Capsicum annum L.), with whitefly (Bemisia tabaci) serving as the vector for transmission. Chili leaf samples with leaf curl symptoms were collected from Guntur, Andhra Pradesh, India. PCR-based detection screened for begomoviral infection and betasatellite in the collected samples. In this study, we have characterized tomato leaf curl Bangladesh betasatellite (ToLCBB) (OQ184745) using universal betasatellite primers. Partial dimer constructs were developed using the betasatellite and the DNA A genome of the chilli leaf curl Ahmedabad virus (ChiLCAV) (MW316419) in pCAMBIA 1302 vector. Both the constructs were mobilized separately into the Agrobacterium strain LBA4404, followed by agroinfiltration into healthy chili plants. Plants co-infiltrated with DNA A and betasatellite dimers exhibited symptoms after 21 days of infiltration, whereas plants infiltrated separately with the partial dimer constructs did not display any symptoms. Prominent symptoms include upward curling, thickening of stem ribs and stunted plant growth. Chili plants infiltrated with the infectious clones of ChiLCAV + ToLCBB and ChiLCAV alone showed positive amplification with ChiLCAV-specific and betasatellite primers. In contrast, plants infiltrated with ToLCBB partial dimer construct did not show any amplification with betasatellite primers. ChiLCAV DNA A titer accumulation was further quantified with qPCR and we observed that there is a significant increase (p < 0.0001) in the accumulation level with ChiLCAV + ToLCBB construct when compared to the ChiLCAV construct alone. Thus, this study highlights the pathogenesis of leaf curl disease in C. annuum caused by the begomovirus complex of ChiLCAV and its associated betasatellite ToLCBB.