Cuticular wax biosynthesis as a way of inducing drought resistance

Abstract

Plants have evolved diverse adaptive strategies to cope with drought or water deficit conditions, such as stomatal closure, maintenance of root growth and water uptake, and biosynthesis of osmoprotectants. Accumulation of cuticular waxes also contributes to drought resistance. However, it is still unclear how cuticular wax biosynthesis is regulated in response to drought and how it is associated with plant responses to drought at the molecular level. The abscisic acid (ABA)-inducible MYB96 transcription factor plays a role in drought resistance. Notably, it also regulates cuticular wax biosynthesis by binding directly to the promoters of genes encoding fatty acid elongating enzymes, such as KCS, KCR and ECR that constitute a rate-limiting step in cuticular wax biosynthesis. In the myb96-1D mutant that constitutively express the MYB96 gene, many of genes involved in cuticular wax biosynthesis are upregulated and accordingly, cuticular wax accumulation is greatly elevated. In contrast, cuticular wax accumulation is reduced in the myb96-1 mutant, linking drought with cuticular wax biosynthesis. It is evident that the MYB96 transcription factor incorporates drought stress signals into a gene regulatory network that modulates cuticular wax biosynthesis under drought stress conditions, providing a first molecular mechanism by which cuticular wax biosynthesis contributes to drought resistance and protection from pathogenic and mechanical damages as well.Drought stress induces a wide array of developmental, physiological and morphological changes in plants. Numerous transcription factors, regulatory proteins

Leaf water status, osmoregulation and secondary metabolism as a model for depicting drought tolerance in Argania spinosa

“…Previous studies had shown that the concentration of wax deposited on leaf surfaces increases significantly under drought stress in various plants, including rose (Jenks et al 2001), peanut (Samdur et al 2003), tree tobacco (Cameron et al 2006), sesame (Kim et al 2007a, b) and barley (González and Ayerbe 2010). Its synthesis stimulated by drought can present a mechanism of resistance and protection from damages, allowing plants to boost water retention and ensure its growth by developing water conservation measures in stressed conditions (Zhang et al 2005;Goodwin and Jenks 2005;Seo and Park 2011). The expression of genes involved in regulating both pathways of biosynthesis, and transport of cuticular wax was detected in some transgenic plants under drought stress (Seo and Park 2011).…”

“…This is due to increases in permeability and loss of integrity in plant membranes (Quan et al 2004). During drought conditions, epicuticular wax load (EWL) increases, thereby minimising cuticular transpiration and maximising leaf water retention (Zhang et al 2005;Goodwin and Jenks 2005;Seo and Park 2011). A positive correlation between EWL and residual transpiration rate (RTR) has previously been demonstrated (Premachandra et al 1992).…”

QTL mapping and loci dissection for leaf epicuticular wax load and canopy temperature depression and their association with QTL for staygreen in Sorghum bicolor under stress

“…Lee and Suh (2015) have also shown that in drought-treated Arabidopsis, MYB96-1D and MYB96-1 upregulates 19 genes involved in wax biosynthesis, including a long-chain acyl-CoA synthase (LACS3) and in transport including an ABC transporter (ABCG11/WBC11/COF1). Others include lipid transfer proteins (LTP) (Seo and Park 2011). Additive effects were recently reported between MYB94 and MYB96 in the activation of cuticular wax biosynthesis in Arabidopsis (Lee et al 2016).…”

“…A Cytochrome P450 family member, CYP704B2, has been shown to catalyze the x-hydroxylation of fatty acids and is required for anther cutin biosynthesis and pollen exine formation in rice (Li et al 2010). A related protein, CYP96A15, which is also upregulated by a Myb gene, is a functional orthologue of Mid-chain Alkane Hydroxylase (MAH1), which converts alkanes to 1 0 alcohols and 1 0 alcohols to ketones in the 1 0 alcohol pathway in wax biosynthesis (Seo and Park 2011). Other genes residing in the locus intervene directly in the reproductive processes (CIPKL4, KAN3, FKL), drought (DRIP1) and vesicular transport (NSF, GGT).…”

Leaf Surface Wax Composition of Genetically Diverse Mulberry (<i>Morus</i> sp.) Genotypes and its Close Association with Expression of Genes Involved in Wax Metabolism

“…Composition of waxes varies from genotype to genotype, as well as due to environmental conditions and development 5 . Many genes associated with biosynthesis of plant waxes have been characterized 6 . Today, two main branches of the wax metabolic pathway are postulated, the so-called decarbonylation pathway, which leads to production of alkanes and aldehydes, and the acyl reduction pathway that produces primary alcohols and esters 3 In a previous report, we examined 291 mulberry genotypes and described the high correlation between leaf post-harvest water loss rates and leaf surface wax amounts 1 .…”