Dark-Induced Hormonal Regulation of Plant Growth and Development

Abstract

The sessile nature of plants has made them extremely sensitive and flexible toward the constant flux of the surrounding environment, particularly light and dark. The light is perceived as a signal by specific receptors which further transduce the information through the signaling intermediates and effector proteins to modulate gene expression. Signal transduction induces changes in hormone levels that alters developmental, physiological and morphological processes. Importance of light for plants growth is well recognized, but a holistic understanding of key molecular and physiological changes governing plants development under dark is awaited. Here, we describe how darkness acts as a signal causing alteration in hormone levels and subsequent modulation of the gene regulatory network throughout plant life. The emphasis of this review is on dark mediated changes in plant hormones, regulation of signaling complex COP/DET/FUS and the transcription factors PIFs which affects developmental events such as apical hook development, elongated hypocotyls, photoperiodic flowering, shortened roots, and plastid development. Furthermore, the role of darkness in shade avoidance and senescence is discussed.

MSD2, an apoplastic Mn-SOD, contributes to root skotomorphogenic growth by modulating ROS distribution in Arabidopsis

“…COP1 mediates HY5 degradation in the dark, whereas light blocks the interaction of COP1 with HY5, consequently promoting the accumulation of HY5 and the transcriptional activation of its downstream target genes [36]. Light and dark conditions also alter phytohormone responses, as light facilitates auxin transport from the shoot apex to the root [37], while darkness induces the expression of phytohormone biosynthesis and signaling-related genes for ethylene and gibberellic acid, which regulate skotomorphogenic development [50]. Analysis of MSD2 expression in a cop1-4 mutant allele showed that COP1 negatively regulates MSD2 expression in the dark but had no effect on MSD2 expression in the light (Fig.…”

Plant Defense Responses to Biotic Stress and Its Interplay With Fluctuating Dark/Light Conditions

“…Mutants with defects in any of these repressor proteins display constitutive photomorphogenic (COP) phenotypes under dark conditions ( Lau and Deng, 2012 ). The repressor proteins are characterized into four categories with overlapping functions and have been studied extensively ( Deepika et al, 2020 ; Pham et al, 2020 ). The first one is COP1, which is a RING-finger-type ubiquitin E3 ligase ( Deng et al, 1992 ).…”

Pest and disease management by red light

“…Furthermore, it can influence growth and developmental processes, including different metabolic pathways in plant–pathogen interactions (Purschwitz, Müller, Kastner, & Fischer, 2006; Thind & Schilder, 2018; Tisch & Schmoll, 2010; van der Horst, Key, & Hellingwerf, 2007). In contrast to optimal light conditions, high and low light intensity, including darkness, induce different signalling and regulation pathways modulated by phytohormones, especially jasmonic acid (JA) and salicylic acid (SA) (Ballaré, 2014; Deepika, Sagar, & Singh, 2020; Roberts & Paul, 2006).…”

“…Various phytohormones play a role in the regulation of plant defence responses depending on the light (Ballaré, 2014; Deepika et al, 2020; Roberts & Paul, 2006). SA is required to establish both local and systemic acquired resistance after pathogen infection.…”