HOS1 Facilitates the Phytochrome B-Mediated Inhibition of PIF4 Function during Hypocotyl Growth in Arabidopsis

摘要: Upon exposure to light, developing seedlings undergo photomorphogenesis, as illustrated by inhibition of hypocotyl elongation, cotyledon opening, and leaf greening. During light signals are sensed multiple photoreceptors, among which the red/far-red light-sensing phytochromes have been extensively studied. However, it is not fully understood how modulate growth. Here, we demonstrated that HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENES 1 (HOS1), known either act E3 ubiquitin ligase or affect chromatin organization, inhibits transcriptional activation activity PHYTOCHROME INTERACTING FACTOR 4 (PIF4), a key transcription factor promotes Consistent with negative regulatory role HOS1 in growth, HOS1-defective mutants exhibited elongated hypocotyls light. Notably, phyB induces inhibiting PIF4 function. Taken together, these observations provide molecular basis for phyB-mediated suppression growth Arabidopsis.