Molecular variation of tomato yellow leaf curl virus in the insect vector Bemisia tabaci

Insect vectors play significant roles in geminivirus spread and evolution in nature. To date little is known about the population dynamics of begomoviruses in their insect vector Bemisia tabaci. In this study we analyzed the genetic variation of tomato yellow leaf curl virus (TYLCV) in its host plant, Solanum lycopersicum, in its transmission vector B. tabaci raised on TYLCV-infected S. lycopersicum plants, and in B. tabaci after being transferred from S. lycopersicum to Gossypium hirsutum. We found that the levels of variability of TYLCV remained stable in S. lycopersicum plants, but increased significantly in both invasive and indigenous species of B. tabaci. We also presented evidence that the elevated mutation frequencies in TYLCV populations from vector whiteflies were caused mainly by mutations that occurred at several distinct sites within the TYLCV genome. Simultaneous introduction of mutations in the hot spots did not affect the ability of TYLCV to be transmitted by B. tabaci, but reduced its pathogenicity in both S. lycopersicum and Nicotiana benthamiana. Our findings provide new information on population variability of TYLCV in its insect vector, extending the knowledge of the influence of insect vector on plant virus population dynamics.