Light signaling and UV‐B‐mediated plant growth regulation

Abstract

Light plays an important role in plants’ growth and development throughout their life cycle. Plants alter their morphological features in response to light cues of varying intensity and quality. Dedicated photoreceptors help plants to perceive light signals of different wavelengths. Activated photoreceptors stimulate the downstream signaling cascades that lead to extensive gene expression changes responsible for physiological and developmental responses. Proteins such as ELONGATED HYPOCOTYL5 (HY5) and CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) act as important factors which modulate light‐regulated gene expression, especially during seedling development. These factors function as central regulatory intermediates not only in red, far‐red, and blue light pathways but also in the UV‐B signaling pathway. UV‐B radiation makes up only a minor fraction of sunlight, yet it imparts many positive and negative effects on plant growth. Studies on UV‐B perception, signaling, and response in plants has considerably surged in recent times. Plants have developed different strategies to use UV‐B as a developmental cue as well as to withstand high doses of UV‐B radiation. Plants’ responses to UV‐B are an integration of its cross‐talks with both environmental factors and phytohormones. This review outlines the current developments in light signaling with a major focus on UV‐B‐mediated plant growth regulation.

COLD-REGULATED GENE27 Integrates Signals from Light and the Circadian Clock to Promote Hypocotyl Growth in Arabidopsis

“…Light signals of various wavelengths are perceived by several photoreceptor families, including phytochromes (red and far-red light), cryptochromes (blue light), phototropins (blue light), and UV-B RESISTANCE LOCUS8 (UVR8, for UV light; Gallagher et al, 1988;Sharrock and Quail, 1989;Lin et al, 1995;Guo et al, 1998;Rizzini et al, 2011;Christie et al, 2012). These photoreceptors are responsible for transducing diverse light information to downstream light signaling components to initiate a variety of cellular and physiological processes (Chen et al, 2014;Ma et al, 2016;Pedmale et al, 2016;Paik and Huq, 2019;Xu, 2019;Jing and Lin, 2020;Yadav et al, 2020;Yu and Liu, 2020). CONSTITUTIVELY PHOTOMORPHOGENIC/DE-ETIOLATED/FUSCA (COP/DET/ FUS) proteins, acting directly downstream of photoreceptors, are biologically active in the nucleus and maintain skotomorphogenesis in the dark (Lau and Deng, 2012;Hoecker, 2017;Podolec and Ulm, 2018;Han et al, 2020).…”

BBX28/BBX29, HY5 and BBX30/31 form a feedback loop to fine‐tune photomorphogenic development

“…Various wavelengths of light are perceived by at least five classes of photoreceptors in plants, including phytochromes, cryptochromes, phototropins, ZEITLUPE family members (ZTL, FKF1 and LKP2) and UV RESISTANCE LOCUS 8 (UVR8) (Galvao and Fankhauser, 2015; Paik and Huq, 2019). These photoreceptors absorb and transduce information about different light types to the downstream signaling pathway and ultimately modulate massive gene expression, which orchestrates adaptive changes in plants in response to the quality, quantity, direction and duration of light (Paik and Huq, 2019; Jing and Lin, 2020; Yadav et al ., 2020; Yu and Liu, 2020).…”

A Positive Feedback Loop of BBX11–BBX21–HY5 Promotes Photomorphogenic Development in Arabidopsis

“…Phytochromes (phyA to phyE) perceive far-red (FR) and red (R) light ( Sharrock and Quail, 1989 ); cryptochromes (CRY1 and CRY2) and phototropins (PHOT1 and PHOT2) sense UV-A and/or blue (B) light ( Gallagher et al., 1988 , Lin et al., 1995 , Guo et al., 1998 ); and UV-B resistance locus 8 (UVR8) absorbs UV-B light ( Rizzini et al., 2011 ). Proper light exposure converts these photoreceptors into biologically active isoforms that work synergistically with downstream components to initiate diverse molecular events and promote photomorphogenesis ( Chen et al., 2014 , Ma et al., 2016 , Pedmale et al., 2016 , Wei et al., 2020 , Yadav et al., 2020 , Yang and Liu, 2020 , Zhai et al., 2020 ).…”