Figure 1.

The mechanism for thermonasty proposed by Park et al. (2019). At warm temperatures, there is an increase in auxin flow from the leaf to the petiole vasculature. In endodermal cells of the adaxial petiole, warm temperatures also enhance PIF4-mediated induction of PID. PID directs the trafficking of PIN3 to the lower membrane of these cells, resulting in a greater flow of auxin to the abaxial epidermis. The associated asymmetric growth between the abaxial and adaxial epidermises causes thermonastic movement. Adapted from Park et al. (2019), Fig. 7.