Geographical distribution and molecular characterization of tomato leaf curl and its vector across the Himalayan foothills in Uttarakhand, India

Abstract

Tomato leaf curl disease is a serious constraint to tomato cultivation across the globe. The disease is characterized by leaf curling, crinkling, stunting and puckering with the drastic reduction in plant growth and yield. During two‐year survey in major tomato‐growing belt of Tarai region located in foothills of Himalayas in Uttarakhand, India, the mean incidence and per cent disease index of the disease were found to be 68.76% and 67.19%, respectively. In the morphological analysis using electron microscopy, pathogen contains twin geminate particles measuring 30 × 20 nm. The PCR amplification using RUGEMF1 and RUGEMR1 primers and sequencing of the amplicons, revealed more than 97% similarity to Tomato leaf curl New Delhi Virus (ToLCNDV). Thus, based on the sequence similarity, morphology and whitefly transmission, begomovirus isolate was recognized as a Tomato leaf curl New Delhi virus and designated as ToLCNDV_[Pant]. Amplification and sequencing of the Bemisia tabaci partial mtCOI gene from the Tarai region revealed the prevalence of Asia‐II‐1 cryptic species in the region. The overall mean pairwise distance across the 10 sequences studied was 0.0139, whereas the reference Asia‐II‐1 distance ranged from 0.0031 to 0.0332. The current investigation will aid in the development of an integrated strategy to ToLCD management.