Figure 8.

A schematic diagram representing high-temperature-mediated suppression of leaf size. Warm temperature positively regulates expression of PIF4 and TCP4 and accumulation of PIF4 in leaf cells. High temperature further promotes binding of PIF4 and TCP4 to the promoter of cell cycle inhibitor KRP1 to induce KRP1 expression, which in turn suppresses cell proliferation and thus leaf size. Our results show that TCP4 is required for transcriptional induction of PIF4 expression (left facing arrow) that subsequently affects accumulation of PIF4 protein and thus its enrichment on KRP1 promoter under warm temperature. The physical interaction between TCP4 and PIF4 may further add to their co-regulatory role for induction of KRP1 expression under high temperature.