ABA Suppresses Root Hair Growth via the OBP4 Transcriptional Regulator

Abstract

Plants modify organ growth and tune morphogenesis in response to various endogenous and environmental cues. At the cellular level, organ growth is often adjusted by alterations in cell growth, but the molecular mechanisms underlying this control remain poorly understood. In this study, we identify the DNA BINDING WITH ONE FINGER (DOF)-type transcription regulator OBF BINDING PROTEIN4 (OBP4) as a repressor of cell growth. Ectopic expression of OBP4 in Arabidopsis (Arabidopsis thaliana) inhibits cell growth, resulting in severe dwarfism and the repression of genes involved in the regulation of water transport, root hair development, and stress responses. Among the basic helix-loop-helix transcription factors known to control root hair growth, OBP4 binds the ROOT HAIR DEFECTIVE6-LIKE2 (RSL2) promoter to repress its expression. The accumulation of OBP4 proteins is detected in expanding root epidermal cells, and its expression level is increased by the application of abscisic acid (ABA) at concentrations sufficient to inhibit root hair growth. ABA-dependent induction of OBP4 is associated with the reduced expression of RSL2. Furthermore, ectopic expression of OBP4 or loss of RSL2 function results in ABAinsensitive root hair growth. Taken together, our results suggest that OBP4-mediated transcriptional repression of RSL2 contributes to the ABA-dependent inhibition of root hair growth in Arabidopsis.

Genome-Wide Identification and Expression Analysis of the Dof Transcription Factor Gene Family in Gossypium hirsutum L.

“…As Dof genes widely participate in the regulation of photoperiodic flowering [5], nitrogen metabolism [9], and plant growth [11], we searched the GhDof homologs, and their functions are listed in Supplementary material 1. Cotton premature senescence has occurred with increasing frequency in recent years and is regulated by stresses, hormones, and genes [25].…”

Conflicting Auxin-Phosphate Signals Impact on RSL2 Expression and ROS-Homeostasis Linked to Root Hair Growth in Arabidopsis

“…Alternatively, high Pi levels could directly repress RSL4/RSL2 expression by an unknown mechanism. Recently, abscisic acid (ABA) throughout the TF OBP4 (OBF BINDING PROTEIN 4) was able to repress RSL2 (and RSL3) expression indicating that multiple hormonal signals on top of auxin may operate in these cells as previously described (Rymen et al 2017). In addition, it is plausible that RSL2 and RSL4 would be able to form protein dimers as reported in other several TFs that contains HLH domain (Feller et al 2011), more precisely heterodimers (e.g., RSL2-RSL4) and homodimers (e.g., RSL2-RSL2 and RSL4-RSL4) with slightly different transcriptional downstream target genes.…”

“…Hormones and environmental cues converge to regulate the expression of RSL4, which controls the final root hair cell size (Yi et al 2011; Lee et al2013; Datta el al. 2015; Song et al 2016; Rymen et al 2017). Although, in this process, other TFs might act in a coordinative manner under specific signals such as Pi-starvation and ethylene as this is the case for EIN3 (ETHYLENE INSENSITIVE 3)/EIL1 (ETHYLENE INSENSITIVE 3-LIKE 1) and LRL3 (LOTUS JAPONICA ROOTHAIRLESS-LIKE1) (Yi et al 2010; Song et al 2016, Feng et al 2017).…”

Rice OsDOF15 contributes to ethylene‐inhibited primary root elongation under salt stress

“…These transcriptional regulators participate in plant growth, development and other processes, including biotic and abiotic stress responses (Yanagisawa, ; Gabriele et al ., ; Noguero et al ., ; Renau‐Morata et al ., ; Rymen et al ., ; Zang et al ., ). Under most conditions, the roles of DOF proteins in these physiological processes involve plant hormones (Gabriele et al ., ; Boccaccini et al ., ; Rymen et al ., ; Huang et al ., ). Ethylene is a crucial, simple gaseous phytohormone (Achard et al ., ; Van de Poel et al ., ) whose biosynthesis is highly regulated at the transcriptional and post‐transcriptional levels (Argueso et al ., ; Yoon, ; Lee & Yoon, ).…”