Detection of Tomato yellow leaf curl Thailand virus transmitted by Bemisia tabaci Asia I in tomato and pepper

Tomato yellow leaf curl Thailand virus (TYLCTHV) has caused serious yield loss of tomato in Thailand for more than three decades. Control of the virus is essential for successful integrated disease management (IDM) strategies. This study investigated the capability of whitefly (Bemisia tabaci) to transmit TYLCTHV on two host plantstomato and pepperand sought to detect the presence of viral DNA in the plants and whiteflies after two transmissions. The new TYLCTHV isolate used in this study (SPN-Tom1A) was 2756 nts long with typical characteristics of TYLCTHV DNA-A. Viral DNA-A (WF-SPN Tom2015) also was detected in viruliferous whiteflies; nucleotide sequence revealed 99% identity to TYLCTHV SPN-Tom1A sequence. In duplicated transmission test, vector B. tabaci Asia I was highly efficient in transmitting TYLCTHV from tomato to tomato by 90-100%, followed by the transmission from tomato to pepper by 55-90%. In contrast, the transmission rate of TYLCTHV pepper to tomato seedlings was nil. Tomato plants showed upward cupping and yellow leaves typical of TYLCTHV infection only when TYLCTHV was transmitted from tomato to tomato, but when transmitted to pepper, the infected peppers were symptomless. Bodies of viruliferous whiteflies fed on tomato and pepper were confirmed by PCR for the presence of TYLCTHV at 58.89-80% and 60-89.45%, respectively. Our results thus provide evidence that pepper infected with TYLCTHV is not a source plant for TYLCTHV transmission to tomato.