The MYB96 Transcription Factor Mediates Abscisic Acid Signaling during Drought Stress Response in Arabidopsis

Abstract

Plant adaptive responses to drought are coordinated by adjusting growth and developmental processes as well as molecular and cellular activities. The root system is the primary site that perceives drought stress signals, and its development is profoundly affected by soil water content. Various growth hormones, particularly abscisic acid (ABA) and auxin, play a critical role in root growth under drought through complex signaling networks. Here, we report that a R2R3-type MYB transcription factor, MYB96, regulates drought stress response by integrating ABA and auxin signals. The MYB96-mediated ABA signals are integrated into an auxin signaling pathway that involves a subset of GH3 genes encoding auxin-conjugating enzymes. A MYB96-overexpressing Arabidopsis (Arabidopsis thaliana) mutant exhibited enhanced drought resistance with reduced lateral roots. In the mutant, while lateral root primordia were normally developed, meristem activation and lateral root elongation were suppressed. In contrast, a T-DNA insertional knockout mutant was more susceptible to drought. Auxin also induces MYB96 primarily in the roots, which in turn induces the GH3 genes and modulates endogenous auxin levels during lateral root development. We propose that MYB96 is a molecular link that mediates ABA-auxin cross talk in drought stress response and lateral root growth, providing an adaptive strategy under drought stress conditions.

Cuticle Biosynthesis in Tomato Leaves Is Developmentally Regulated by Abscisic Acid

“…Previous studies have shown that environmental stresses, such as drought, increase ABA levels, resulting in the increased production of cuticular waxes Seo et al, 2009Seo et al, , 2011Wang et al, 2012). In this study, we conclude that ABA regulation of cuticle formation is an intrinsic aspect of leaf development.…”

“…In addition, the presence of cis-ABA-responsive elements in the promoters of some wax-related genes, such as CER6 (Hooker et al, 2002), suggests that ABA directly regulates wax synthesis. Moreover, some Arabidopsis transcriptions factors that are associated with cuticle biosynthesis, such as MYB96, are known to be regulated by ABA and to be part of the ABA-mediated signaling pathway (Cominelli et al, 2008;Seo et al, 2009;Lee et al, 2015). Lastly, Cui et al (2016) showed that the expression of some cuticle related genes was affected in Arabidopsis ABA mutants, further suggesting a role for ABA in cuticle development.…”

“…While the levels of waxes, and in particular alkanes, were reported to increase following ABA application, no such change in the abundance of cutin monomers was observed, suggesting that other factors trigger changes in the cuticle following water stress . Furthermore, the expression levels of numerous wax biosynthesis-related genes are known to respond to ABA treatment Seo et al, 2009Seo et al, , 2011Wang et al, 2012). For example, the expression of ECERIFERUM1 (CER1), which encodes an enzyme that generates alkanes from very-long-chain acyl-CoA (Bernard et al, 2012), is induced by ABA treatments ).…”

Overexpression of AtMYB52 Confers ABA Hypersensitivity and Drought Tolerance

“…AtMYB2 regulates a subset of ABA-responsive genes, and its overexpression enhances ABA sensitivity (Abe et al, 2003). Similarly, AtMYB15, AtMYB44 and AtMYB96 are involved in ABA and drought responses (Ding et al, 2009;Jung et al, 2008;Seo et al, 2009), whereas AtMYB41 regulates osmotic response (Lippold et al, 2009). In this study, we showed that overexpression of AtMYB52 conferred ABA hypersensitivity, drought tolerance and salt sensitivity, which indicates that AtMYB52 also is involved in ABA and stress responses.…”

Analysis of biochemical variations and microRNA expression in wild (Ipomoea campanulata) and cultivated (Jacquemontia pentantha) species exposed to in vivo water stress

“…In plants, stress-induced changes in gene expression operate at multiple levels; transcriptional, post-transcriptional and post-translational regulations (Seo et al 2009;Sakuma et al 2006;Bartles and Sunkar 2005;Sunkar et al 2012). Stressinduced transcriptional regulation has been extensively studied over the past couple of decades .…”