Molecular characterization of coat protein of tomato leaf curl New Delhi virus (Begomovirus, F: Geminiviridae) infecting ridge gourd and its expression studies in Escherichia coli

Ridge gourd (Luffa acutangula L. Roxb.) is one of the most important vegetable crops in India. It belongs to the family Cucurbitaceae; like any other crop, it is also highly susceptible to biotic and abiotic stresses. Among the biotic stresses, tomato leaf curl New Delhi Virus (ToLCNDV) is becoming a major constraint in cultivation of ridge gourd. ToLCNDV is naturally transmitted through whitefly in a circulative and persistent manner and causes the yield loss to the tune of 40-100% (Patil et al. in Virus Dis 28(2):146-155, 2017. https://doi.org/10.1007/s13337-017-0376-6). In present investigation, coat protein gene of ToLCNDV was used to construct a phylogenetic tree showing no host-specificity in the population studied. Further, for in vitro expression studies, the coat protein gene was cloned into pET28a and successfully overexpressed in E. coli BL21 (DE3) cells. The expression of recombinant coat protein varied with different induction time and the highest expression was recorded in 4 h of induction period, incubated with 1-mM IPTG at 37 degrees C. Overexpressed protein was further purified using Ni-NTA column and confirmed through SDS-PAGE analysis. The present study will help to develop ELISA-based detection tools to diagnose the disease as well as to take up immediate management practices.