A PIF7-CONSTANS-Centered Molecular Regulatory Network Underlying Shade-Accelerated Flowering

Area of Science:

• Plant Biology
• Molecular Biology
• Genetics

Background:

• Plants exhibit shade-avoidance syndrome (SAS) to compete for light, involving architectural changes and early flowering.
• Previous research focused on seedling hypocotyl elongation, leaving molecular mechanisms of shade-accelerated flowering in adult plants unclear.

Purpose of the Study:

• To elucidate the molecular mechanisms controlling shade-accelerated flowering in adult plants.

Main Methods:

• Investigated the roles of CONSTANS (CO), PHYTOCHROME-INTERACTING FACTOR 7 (PIF7), and LONG HYPOCOTYL IN FAR-RED1 (HFR1) in regulating flowering time under shade.
• Analyzed gene expression of FLOWERING LOCUS T (FT), TSF, SOC1, and SPLs.

Main Results:

• CO and PIF7 have additive effects on shade-induced flowering.
• HFR1 represses flowering by preventing CO and PIF7 binding to target gene promoters (FT and pri-MIR156E/F).
• Under shade, PIF7 and CO upregulate FT, TSF, SOC1, and SPLs, accelerating flowering, with HFR1 acting as a balance. PIF7's flowering role is independent of phyA.

Conclusions:

• Identified a regulatory network involving CO, PIF7, and HFR1 that links light signals to flowering time under shade.
• This study establishes a crucial connection between light perception and the genetic pathways governing the transition to flowering.