Synergism of red and blue light in the control of Arabidopsis gene expression and development.

SELLARO, R.; HOECKER, U.; YANOVSKY, M. J.; CHORY, J.; CASAL, J. J.

CURRENT BIOLOGY

CELL PRESS

Año: 2009 vol. 19 p. 1216 - 1220

0960-9822

The synergism between red and blue light in the control ofplant growth and development [1, 2] requires the coactionof the red light photoreceptor phytochrome B (phyB) andthe blue light and UV-A receptor cryptochromes (cry) [3].Here, we describe the mechanism of the coaction of thesephotoreceptors in controlling both development and physiology.In seedlings grown under red light, a transient supplementwith blue light induced persistent changes in thetranscriptome and growth patterns. Blue light enhancedthe expression of the transcription factors LONG HYPOCOTYL 5 (HY5) and HOMOLOG OF HY5 (HYH) [4] and ofSUPPRESSOR OF PHYA 1 (SPA1) and SPA4 [5]. HY5 andHYH enhanced phyB signaling output beyond the durationof the blue light signal, and, contrary to their known role asrepressors of phyA signaling [5], SPA1 and SPA4 alsoenhanced phyB signaling. These observations demonstratethat the mechanism of synergism involves the promotion bycry of positive regulators of phyB signaling. The persistenceof the light-derived signal into the night commits the seedlingto a morphogenetic and physiological program consistentwith a photosynthetic lifestyle.