and Play Dual Roles in Regulation of Shade Avoidance Response under Different Environments in .

Polar auxin transport mediated by PIN-FORMED (PIN) proteins is critical for plant growth and development. As an environmental cue, shade stimulates hypocotyls, petiole, and stem elongation by inducing auxin synthesis and asymmetric distributions, which is modulated by PIN3,4,7 in . Here, we characterize the and , which are the orthologs of ,,, in model legume species . Under the low Red:Far-Red (R:FR) ratio light, the expression of and is induced, and shadeavoidance response is disrupted in double mutant, indicating that and have a conserved function in shade response. Surprisingly, under the normal growth condition, displayed the constitutive shade avoidance responses, such as the elongated petiole, smaller leaf, and increased auxin and chlorophyll content. Therefore, and play dual roles in regulation of shadeavoidance response under different environments. Furthermore, these data suggest that ,, and its orthologs have evolved conserved and specific functions among species.