Begomoviruses Associated to Pepper Yellow Leaf Curl Disease in Thailand

Yellow leaf curl disease (YLCD) of pepper has been re-emerging in most pepper production areas in Thailand causing serious damages to marketable yields. To develop resistant pepper variety for disease defence, the begomoviruses associated with YLCD were identified based on DNA-A nucleotide sequences. Field surveys for YLCD incidences were conducted in 10 provinces across the country during May 2012 to November 2014. YLCD was found to be distributed in most of the chili pepper production fields with varying degree of disease incidences, where the highest infection percentage was about 95% in one field in Kanchanaburi province. Six isolates of YLC-pepper begomoviruses from 6 locations were isolated by using rolling circle amplification (RCA), and the obtained circular DNAs were cloned and sequenced. The cloned DNA-A sequences revealed characteristic of begomovirus associated to YLCD pepper with 90.4- 90.7% identical to those of previously reported records in GenBank database. Virus species were further identified using Sequence Demarcation Tool (SDT) program based on DNA-A component sequences, using the cut-off value at <91%. Results indicated that five isolates were designated to be Pepper yellow leaf curl Thailand virus (PepYLCTHV), and one isolate was Tobacco leaf curl Thailand virus (TbLCTHV). This is the first report on the diverse genomes of begomoviruses infecting pepper in Thailand. The transmission rate of PepYLCTHV by whitefly, Bemisia tabaci Genn. From YLC-pepper to pepper seedlings was 100% under glasshouse condition, but the virus could not be transmitted to tomato seedlings. Both DNA-A and DNA-B components identity to PepYLCTHV were detected in a single whitefly body.