The whitefly, Bemisia tabaci, is an agroeconomic pest species complex for which resistance breeding has remained largely unsuccessful. Although partial resistance against B. tabaci has been established, it is often broken at the high temperatures the whitefly prefers. A possible successful approach would be to identify so-called plant susceptibility (S) genes that are required for B. tabaci’s success. We used a yeast two-hybrid screen to identify the transcription factor GOLDEN2-Like (GLK) proteins, GLK1 and GLK2, as interactors of the B. tabaci specific effector protein S1. Fecundity bioassays on Arabidopsis loss-of-function mutants revealed that GLK1, but not GLK2, acts as a susceptibility gene. Co-localization, bimolecular fluorescence complementation (BiFC) and co-immunoprecipitation (Co-IP) assays showed that AtGLK1 and S1 interact in the nucleus of the plant. Furthermore, we found that Solanum lycopersicum GLK1 (SlGLK1) is able to interact with S1 in the nucleus and fecundity bioassays on slglk1/slglk2 tomato mutant lines showed increased resistance towards whiteflies. In conclusion, the higher whitefly resistance observed in glk1 loss-of-function mutants shows that GLK1 is a B. tabaci susceptibility gene Arabidopsis and modulates whitefly resistance in tomato.
Kleeff et al. (Tue,) studied this question.