Cytokinin-mediated enhancement of potato growth and yield by Verticillium Dahliae effector VDAL under low temperature stress

The pathogen Verticillium dahliae secreted effector V. dahliae Aspf2-like protein (VDAL) has been found to cause leaf wilting in cotton, but the ectopic expression of VDAL-encoding gene enhances the resistance to V. dahliae in cotton and Arabidopsis. The application of the VDAL protein powder with optimal dosage promotes the growth and yield in multiple crop species, such as rice and wheat. However, the promotive effects of VDAL on these aspects are sporadically reported in asexually propagated species, including potato, while the molecular regulatory network involved in the process remains unclear. In this study, we observed that VDAL promotes sprouting of the potato pre-basic seed (PBS) tubers and enhances the development of both above-ground and below-ground tissues. Strikingly, VDAL increases the tuber yield in both greenhouse and field trials by up to 18.97%. The time-course transcriptomic analysis and the endogenous phytohormone detection revealed that cytokinin may play an important role in response to VDAL-promoted growth. Interestingly, VDAL-treated PBS tubers show higher resistance to cold temperature (late-spring cold), a phenomenon that is diminished when the lovastatin, a cytokinin inhibitor is applied, indicating that the VDAL-promoted potato growth, particularly under low temperature, is associated with cytokinin.