Begomovirus causing leaf curl disease in tomato (Lycopersicon esculentum L.) in sub-Himalayan West Bengal, India

Abstract

Tomato (Lycopersicon esculentum L.) is an extensively cultivated vegetable crop in India. In the year 2009, a survey was conducted to find leaf curls of tomato in different locations of sub-Himalayan West Bengal, India. During the survey a severe leaf curl disease was observed. The characteristic disease symptoms (puckered leaves) and presence of whitefly (Bemisia tabaci) population indicated the possibility of begomovirus infection. Total DNA was extracted from the infected samples and PCR was carried out using begomovirus specific primers. An amplicon of expected size ( ̴1280 bp) was found when PALIc1960 and PARIv722 were used as primers in agarose gel electrophoresis. The PCR Amplicons of two samples (collected from two different places of present study area) were cloned and sequenced (GenBank accession nos. HM856626 and HM856627). The sequence data analysis of partial coat protein gene (AV1), full replication enhancer protein gene (AC3) and partial transcription activator protein gene (AC2) of 831 nt revealed highest 98% similarities with several isolates of Tobacco curly shoot virus (TBCSV) at both nucleotide and amino acid levels. The phylogenetic analysis also showed close relationship of the present isolates with different variants of TbCSV. Based on highest sequence similarities and closest relationships with TbCSV the viruses (present in infected tomato plants) were considered as Begomovirus. Transmission of the virus in tomato could not be done by sap transmission procedure. In experimental insect transmission tests, test plants showed symptoms very much like the natural symptoms. Artificial transmission was confirmed by comparing the PCR Amplicons raised from the experimentally infected plants.