Figure 1.

Scheme of the Cellular Processes Affected by phot1 and phot2 and Their Fluence Dependence.

The phot1 protein functions as a photoreceptor for phototropism and chloroplast photoaccumulation under a broad fluence range. phot2 functions as a photoreceptor for chloroplast photoaccumulation at moderate fluences and photoavoidance at high fluences. In addition, phot2 can function as a photoreceptor for phototropism under high fluence. Both phot1 and phot2 function as redundant photoreceptors that control stomatal opening. The initial photochemical step of cysteinyl-flavin adduct formation is identical in both of these plant blue light photoreceptors. The energy of a blue-light photon is designated hν.