PAR1 and PAR2 integrate shade and hormone transcriptional networks

Abstract

PHYTOCHROME RAPIDLY REGULATED1 (PAR1) and PAR2 are two negative regulators of shade avoidance syndrome (SAS) responses in Arabidopsis. PAR1 and PAR2 belong to the bHLH family of transcription factors and act as direct transcriptional repressors of auxin- and brassinosteroid-responsive genes. These observations led us to propose that PAR1 and PAR2 might integrate shade and hormone signals. After plant proximity perception by the phytochrome photoreceptors, the expression of PAR1, PAR2 and dozens of additional PAR genes is affected, initiating a complex web of transcriptional events instrumental for the establishment of the SAS responses.