The MYB96 Transcription Factor Regulates Cuticular Wax Biosynthesis under Drought Conditions inArabidopsis 

Abstract

Drought stress activates several defense responses in plants, such as stomatal closure, maintenance of root water uptake, and synthesis of osmoprotectants. Accumulating evidence suggests that deposition of cuticular waxes is also associated with plant responses to cellular dehydration. Yet, how cuticular wax biosynthesis is regulated in response to drought is unknown. We have recently reported that an Arabidopsis thaliana abscisic acid (ABA)-responsive R2R3-type MYB transcription factor, MYB96, promotes drought resistance. Here, we show that transcriptional activation of cuticular wax biosynthesis by MYB96 contributes to drought resistance. Microarray assays showed that a group of wax biosynthetic genes is upregulated in the activation-tagged myb96-1D mutant but downregulated in the MYB96-deficient myb96-1 mutant. Cuticular wax accumulation was altered accordingly in the mutants. In addition, activation of cuticular wax biosynthesis by drought and ABA requires MYB96. By contrast, biosynthesis of cutin monomers was only marginally affected in the mutants. Notably, the MYB96 protein acts as a transcriptional activator of genes encoding very-long-chain fatty acid-condensing enzymes involved in cuticular wax biosynthesis by directly binding to conserved sequence motifs present in the gene promoters. These results demonstrate that ABA-mediated MYB96 activation of cuticular wax biosynthesis serves as a drought resistance mechanism.

Putative megaenzyme DWA1 plays essential roles in drought resistance by regulating stress-induced wax deposition in rice

“…The inducible wax accumulation is primarily due to an increase in the level of alkanes, which are the most abundant components of the cuticular wax in Arabidopsis. It has been proposed that cuticular alkanes confer greater resistance to water diffusion than VLCFAs (13,19). However, total FAs are the major constituents of cuticular wax in rice (16,23), and we obtained similar results in this study.…”

“…Modulating the expression of rice SHN1/WIN1 homolog wax synthesis regulator 1 (OsWR1) altered wax production and drought tolerance (23). It is unknown how cuticular wax biosynthesis is regulated under drought stress; however, one recent report has shown that MYB96 regulates some wax-biosynthetic genes in Arabidopsis, suggesting it may be required for droughtinduced cuticular wax biosynthesis (13).…”

“…Most of the biosynthetic steps were revealed by identifying wax-related genes of the eceriferum (cer) and glossy (gl) mutants in Arabidopsis and maize, respectively (3,4,6). These genes encode diverse proteins, including biosynthetic enzymes (CER6/CUT1, CER8/LACS1, and GL8) (7)(8)(9), wax transporters (CER5/ABCG12) (10), and transcription factors (e.g., WAX INDUCER1/SHINE1 [WIN1/SHN1], MYB30, MYB96) (11)(12)(13). To date, only a few genes involved in cuticular wax biosynthesis have been identified in rice.…”

MYB30 regulates root cell elongation under abscisic acid signaling

“…Recently, it was reported that MYB94 and MYB96, which belong to the same S1 MYB type subgroup of MYB30, regulate gene expression under ABA signaling in plant shoots [19,20]. Under drought stress, MYB94 and MYB96 are upregulated, and these MYB transcription factors positively regulate the gene expression involved in very-long chain fatty acid biosynthesis.…”

MYB transcription factor genes as regulators for plant responses: an overview

“…The transcriptional activation of cuticular wax biosynthesis by MYB96 contributed to drought resistance in Arabidopsis thaliana (Seo et al 2011). Chen et al (2005a) isolated a drought-inducible MYB gene, designated as BcMYB1, from drought tolerant Boea crassifolia which encoded a typical R2R3-MYB transcription factor belonging to the subgroup 11 of the R2R3-MYB protein family.…”