The ELF4–ELF3–LUX complex links the circadian... : Nature (original) (raw)

The circadian clock is required for adaptive responses to daily and seasonal changes in environmental conditions . Light and the circadian clock interact to consolidate the phase of hypocotyl cell elongation to peak at dawn under diurnal cycles in Arabidopsis thaliana . Here we identify a protein complex (called the evening complex)—composed of the proteins encoded by EARLY FLOWERING 3 ( ELF3 ), ELF4 and the transcription-factor-encoding gene LUX ARRHYTHMO ( LUX ; also known as PHYTOCLOCK 1 )—that directly regulates plant growth . ELF3 is both necessary and sufficient to form a complex between ELF4 and LUX, and the complex is diurnally regulated, peaking at dusk. ELF3 , ELF4 and LUX are required for the proper expression of the growth-promoting transcription factors encoded by PHYTOCHROME INTERACTING FACTOR 4 ( PIF4 ) and PIF5 (also known as PHYTOCHROME INTERACTING FACTOR 3-LIKE 6 ) under diurnal conditions . LUX targets the complex to the promoters of PIF4 and PIF5 in vivo . Mutations in PIF4 and/or PIF5 are epistatic to the loss of the ELF4–ELF3–LUX complex, suggesting that regulation of PIF4 and PIF5 is a crucial function of the complex. Therefore, the evening complex underlies the molecular basis for circadian gating of hypocotyl growth in the early evening.