603 / 2019-04-22 12:06:22

Developmental Programming of Auxin Flow Underlies Thermonastic Leaf Movement

auxin trasport,PID,temperature

Growth and Development > Growth and Development

Plants exhibit diverse polar behaviors in response to directional and non-directional environmental signals, termed tropic and nastic movements, respectively. It is well understood how plants incorporate directional information into tropic behaviors. However, it remains elusive how the polarity of nastic behaviors is specified by non-directional stimuli, such as ambient temperatures. Here, we demonstrated that a developmentally programmed polarity of auxin flow underlies thermo-induced leaf hyponasty in Arabidopsis. At warm temperatures, PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) stimulates auxin production in the leaf, resulting in its accumulation in leaf petiole, where PIF4 directly activates a gene encoding the PINOID (PID) protein kinase. PID is involved in the polarization of the auxin transporter PIN-FORMED 3 to the outer membranes of petiole cells. Notably, the leaf polarity-determining ASYMMETRIC LEAVES 1 (AS1) directs the PID induction to occur predominantly in the abaxial petiole region. These observations indicate that the integration of the PIF4-mediated auxin biosynthesis and polar transport and the AS1-mediated developmental shaping of polar auxin flow coordinate leaf thermonasty, which facilitates leaf cooling under warm environments. We believe that leaf thermonasty is a suitable model system for studying developmental programming of environmental adaptation in plants.