Occurrence and distribution of begomoviruses infecting tomatoes, peppers and cucurbits in Thailand

Incidence of begomoviruses infecting tomatoes, peppers and cucurbits was investigated in major production fields in the north, northeastern, central and southern regions of Thailand between January 2015 and June 2017. Of 585 samples subjected to begomovirus detection by polymerase chain reaction (PCR), 57% were positive for begomovirus infection. Nucleotide sequence analysis of coat protein (CP) and replication initiation protein (Rep) genes identified 15 previously known begomovirus species, 7 of which were reported infecting these crops in Thailand for the first time. A candidate novel bipartite begomovirus designated Melon yellow mosaic virus was also identified in melons from a northeastern province of Thailand. The predominant begomovirus species were different depending on the host plant (Tomato yellow leaf curl Thailand virus [TYLCTHV] for tomato, Pepper yellow leaf curl Thailand virus [PepYLCTHV] for pepper, Tomato leaf curl New Delhi virus [ToLCNDV] for loofah, bitter gourd, cucumber and melon, and Squash leaf curl China virus [SLCCNV] for pumpkin and wax gourd) and location. The update on diversity and distribution of begomoviruses obtained from this study provides useful information for further epidemiological study and support development of effective disease management through selective use of resistant cultivars suitable for particular plants and locations. Additionally, these data can be applied for development of diagnostic assays to specifically detect begomoviruses for continuous monitoring of viral diversity in these economic crops.