Arabidopsis NF-YCs play dual roles in repressing brassinosteroid biosynthesis and signaling during light-regulated hypocotyl elongation

Abstract

Light functions as the primary environmental stimulus and brassinosteroids (BRs) as important endogenous growth regulators throughout the plant lifecycle. Photomorphogenesis involves a series of vital developmental processes that require the suppression of BR-mediated seedling growth, but the mechanism underlying the light-controlled regulation of the BR pathway remain unclear. Here, we reveal that nuclear factor YC proteins (NF-YCs) function as essential repressors of the BR pathway during light-controlled hypocotyl growth in Arabidopsis thaliana. In the light, NF-YCs inhibit BR biosynthesis by directly targeting the promoter of the BR biosynthesis gene BR6ox2 and repressing its transcription. NF-YCs also interact with BIN2, a critical repressor of BR signaling, and facilitate its stabilization by promoting its Tyr200 autophosphorylation, thus inhibiting the BR signaling pathway. Consistently, loss-of-function mutants of NF-YCs show etiolated growth and constitutive BR responses, even in the light. Our findings uncover a dual role of NF-YCs in repressing BR biosynthesis and signaling, providing mechanistic insights into how light antagonizes the BR pathway to ensure photomorphogenic growth in Arabidopsis.

Integration of Light and Brassinosteroid Signaling during Seedling Establishment

“…2021, 22, x FOR PEER REVIEW 2 of 21 [7][8][9][10][11]. A number of significant studies have been conducted to elucidate the close link between light and BR cascades in recent years [12][13][14][15][16][17][18][19]. Here, we summarize the light and BR signal events in seedling morphogenesis, as well as provide an overview of the molecular framework for oppositely regulation of seedling morphogenesis by light and BRs.…”

“…NUCLEAR FACTOR-Y C PROTEINS (NF-YCs) are subunits of NF-Y heterotrimeric complex that regulate target gene expression by specifically binding to the CCAAT-box-containing promoters [ 142 ]. NF-YCs not only inhibit BR biosynthesis by directly targeting the promoter of the BR biosynthesis gene BR6ox2 , but also interact with BIN2 to promote its Tyr200 autophosphorylation and protein stabilization, resulting in inhibiting the BR signaling pathway during light-controlled hypocotyl growth [ 19 ]. Therefore, photomorphogenic-promoting regulators NF-YCs repress BR biosynthesis and signaling to regulate seedling development.…”

“…Extensive studies have revealed the complicated but delicate light and BR pathways in regulating plant growth and development [7][8][9][10][11]. A number of significant studies have been conducted to elucidate the close link between light and BR cascades in recent years [12][13][14][15][16][17][18][19]. Here, we summarize the light and BR signal events Int.…”

“…Extensive studies have revealed the complicated but delicate light and BR pathways in regulating plant growth and development [ 7 , 8 , 9 , 10 , 11 ]. A number of significant studies have been conducted to elucidate the close link between light and BR cascades in recent years [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. Here, we summarize the light and BR signal events in seedling morphogenesis, as well as provide an overview of the molecular framework for oppositely regulation of seedling morphogenesis by light and BRs.…”

Deciphering Novel Transcriptional Regulators of Soybean Hypocotyl Elongation Based on Gene Co-expression Network Analysis

“…Once exposed to light, hypocotyl elongation is inhibited. So far, a variety of photoreceptors have been found to be involved in the regulation of hypocotyl elongation (Yu et al, 2013 ; Srivastava et al, 2015 ; Hu et al, 2021 ; Lin et al, 2021 ; Zhang et al, 2021 ; Zhong et al, 2021 ). For example, mutations of phytochrome A (PHYA) and phytochrome B (PHYB) caused insensitivity to far-red and red light in terms of the inhibition of hypocotyl elongation response (Seo et al, 2009 ; Lee et al, 2012 ; Zhong et al, 2012 ), indicating that PHYA and PHYB mediate the inhibition of hypocotyl elongation by far-red light and red light, respectively.…”