First report of Pepper virus A naturally infecting tomato in India.
In October 2018, diseased tomato plants (Solanum lycopersicum) were observed in a field from Nashik, Maharashtra state in India. The plants showed symptoms including leaf yellowing, mosaic and mottling. Leaf samples from four symptomatic plants (NSK-Tom-01-04) were tested with antisera raised against Cucumber mosaic virus, Groundnut bud necrosis virus and Tobacco mosaic virus (TMV), and a broad-spectrum antiserum against Cowpea mild mottle virus (CPMMV) in direct antigen coating (DAC)-ELISA. Three samples reacted positively with the CPMMV antiserum (NSK-Tom-01, NSK-Tom-02 and NSK-Tom-03) and the fourth sample (NSK-Tom-03) reacted positively only with the TMV antiserum. Mechanical sap transmission of the CPMMV-positive leaf samples produced similar symptoms on tomato plants 8-10 days post-inoculation. To confirm infection, the inoculated plants were tested using the CPMMV antiserum in DAC-ELISA and they reacted positively. The amplicon from the NSK-Tom-01 isolate was cloned into a pGEM-T Easy vector and sequenced. BLAST analysis of the sequence obtained (MK783696) showed the highest identity for both nucleotide (83%) and amino acid sequences (99%) with a CP sequence of Pepper virus A (PepVA; KU726694 and KU923763) isolated from chilli pepper. A phylogenetic tree based on the amino acid sequences of complete CP gene of Pepper virus A and other carlaviruses constructed using MEGA X, revealed that the NSK-Tom-01 isolate of PepVA (MK783696) is closely clustered with other isolates of PepVA (KU726694 and KU923763). This is thought to be the first report of PepVA in tomato in India.