Illuminating Progress in Phytochrome-Mediated Light Signaling Pathways. (October 2015)

• Record Type: Journal Article
• Authors: Xu, Xiaosa; Paik, Inyup; Zhu, Ling; Huq, Enamul
• Is Part Of: Trends in plant science. Volume 20:Number 10(2015)
• Page Start: 641
• Page End: 650
• Publication Date: 2015-10
• Subjects: Botany -- Periodicals; Botanique -- Périodiques; Botany; Periodicals; 580.5
• DOI: 10.1016/j.tplants.2015.06.010
• Languages: English
• ISSNs: 1360-1385

Abstract

Abstract : Light signals regulate a plethora of plant responses throughout their life cycle, especially the red and far-red regions of the light spectrum perceived by the phytochrome family of photoreceptors. However, the mechanisms by which phytochromes regulate gene expression and downstream responses remain elusive. Several recent studies have unraveled the details on how phytochromes regulate photomorphogenesis. These include the identification of E3 ligases that degrade PHYTOCHROME INTERACTING FACTOR (PIF) proteins, key negative regulators, in response to light, a better view of how phytochromes inhibit another key negative regulator, CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1), and an understanding of why plants evolved multiple negative regulators to repress photomorphogenesis in darkness. These advances will surely fuel future research on many unanswered questions that have intrigued plant photobiologists for decades. Trends: Two classes of repressors called COP/DET/FUS complex and PIFs synergistically repress photomorphogenesis in darkness. Light signals perceived by phytochromes inhibit these repressors to promote photomorphogenesis. CUL3 LRB induces polyubiquitylation and subsequent co-degradation of PIF3 and PHYB through the 26S proteasome pathway. CUL4 COP1–SPA E3 ligase promotes rapid light-induced degradation of PIF1 to promote photomorphogenesis. Phytochromes directly interact with SPA1 and reorganize the COP1–SPA interaction to inhibit COP1 activity.