Characterization of begomoviruses associated with emerging mosaic disease of ivy gourd (Coccinia grandis L.) in Tamil Nadu, India

A systematic field survey was conducted in ivy gourd fields of Tamil Nadu during the year 2019-2021. The infected plants manifesting prominent chlorosis, mosaic, puckering, and yellow mosaic symptoms on leaves were tested through polymerase chain reaction (PCR) assay for the infection of begomoviruses. Amplicons of PCR from 5 samples were sequenced. 4 samples were infected with tomato leaf curl New Delhi virus (ToLCNDV) and one with Coccinia mosaic Tamil Nadu virus (CoMoTNV). The nucleotide sequences from isolates IGT-1 (OR041745) and IGP-1 (OR041746) have an identity of 96-98% with ToLCNDV isolate infecting chrysanthemum (MG758145) from Karnataka. Another isolate IGD-1 (OR041747) had 99.3% identity with tomato infecting ToLCNDV isolate (MW538662) from Raipur and isolate IGE-1 (OR041748) had 98.4% highest identity with the previously reported ToLCNDV isolates of India infecting bitter gourd. The IGS-1 (OR028863) isolate 98.9% identity at the nucleotide level with previously reported CoMoTNV (KY860899) infecting ivy gourd from Tamil Nadu. Phylogenetic analysis revealed that ToLCNDV isolates infecting ivy gourd were grouped under three different clusters reported previously reported from different parts of the globe. The present investigation reports the emergence of begomoviruses (ToLCNDV and CoMoTNV) on ivy gourd growing in different parts of Tamil Nadu.