Co-infection and recombination-driven emergence of begomovirus complex causing mosaic disease in muskmelon (Cucumis melo L.).

BACKGROUND: Muskmelon (Cucumis melo L.) is an economically important crop, and mosaic disease is a major constraint to its cultivation in India. The disease is caused by begomoviruses (Family: Geminiviridae) transmitted by the whitefly (Bemisia tabaci). METHODS AND RESULTS: In 2023, symptomatic muskmelon samples were collected from fields in the Mirzapur region of Uttar Pradesh, India. PCR and rolling circle amplification were performed, followed by cloning and sequencing. This identified mixed infections involving three DNA-A and two DNA-B components. Two bipartite begomoviruses, Begomovirus solanumdelhiense (ToLCNDV) and Begomovirus solanumpalampurense (ToLCPalV), were detected. In addition, a monopartite begomovirus, Begomovirus caricae (PaLCuV), was identified for the first time in muskmelon. Phylogenetic and recombination analyses confirmed inter- and intra-species recombination events, highlighting the evolutionary dynamics of these viruses. CONCLUSION: Although monopartite begomoviruses have been reported from muskmelon elsewhere, to the best of our knowledge, this is the first report of PaLCuV infecting muskmelon in India. Our findings reveal a begomoviral complex involving both bipartite and monopartite viruses, thereby underscoring the importance of recombination-driven emergence in cucurbit crops.