A Gene Encoding a SHINE1/WAX INDUCER1 Transcription Factor Controls Cuticular Wax in Barley

Abstract

All land plants seal their above ground body parts with a lipid-rich hydrophobic barrier called the cuticle to protect themselves from dehydration and other terrestrial threats. Mutational studies in several model species have identified multiple loci regulating cuticular metabolism and development. Of particular importance are the eceriferum (cer) mutants characterized by a loss of cuticular wax. Some barley cer mutants, including cer-x, show defects in the distinctive β-diketone-enriched wax bloom on reproductive stage leaf sheaths, stems, and spikes. We exploited extensive allelic populations, near-isogenic lines, and powerful genotyping platforms to identify variation in the HvWAX INDUCER1 (HvWIN1) gene, encoding a SHINE transcription factor, as underlying cer-x. Comparing the cer-x allelic glossy sheath4.l Bowman Near Isogenic Line BW407 to cv. Bowman revealed an increased cuticular permeability in tissues showing reduced accumulation of β-diketones and altered cuticular metabolic gene expression in BW407. Analyses across the barley pangenome and hundreds of exome-capture datasets revealed high sequence conservation of HvWIN1 and two non-synonymous variants exclusive to the cultivated germplasm. Taken together, we suggest that variation in HvWIN1 controls multiple cuticular features in barley.

Transcription Factor TaMYB30 Activates Wheat Wax Biosynthesis

“…The SHINE (SHN) clade of the AP2 domain transcription factors AtSHN1, AtSHN2, and AtSHN3 were first identified as transcriptional activators of cuticle lipid biosynthesis in the dicot model plant Arabidopsis thaliana [ 32 , 33 , 34 ]. Orthologs of AtSHN1, AtSHN2, and AtSHN3 have been characterized as key regulators of wax biosynthesis in other plant species such as Hordeum vulgare , T. aestivum , and Physcomitrium patens [ 35 , 36 , 37 , 38 , 39 ]. In addition, myeloblastosis (MYB)-type transcription factors AtMYB16, AtMYB30, AtMYB41, AtMYB94, AtMYB96, and AtMYB106 are revealed to become widely involved in the transcriptional regulation of wax biosynthesis in A. thaliana [ 1 , 2 , 3 , 40 , 41 , 42 ].…”

Drought-Induced Changes in Leaf Morphology and Anatomy: Overview, Implications and Perspectives

“…Glaucousness, a bluish-white coloring caused by densely dispersed epicuticular wax crystalloids, is a common outcome of epicuticular wax accumulation on plant surfaces. These phenomena decrease the leaf temperature by the reflectance enhancement of radiations which is helpful for the survival of leaves in water-deficient environments [88,92]. Xerophytic plants have more thickness in their cuticles to the enhancement in the production of cuticular waxes from the epidermal cells of the leaves [93].…”

Toward a smart skin: Harnessing cuticle biosynthesis for crop adaptation to drought, salinity, temperature, and ultraviolet stress

“…For instance, overexpression of TaSHN1/WAX INDUCER1 ( TaWIN1 ), wheat homologs of Arabidopsis AtSHN1 , resulted in increased accumulation of wax alkanes in wheat leaves ( Bi et al, 2018 ). Silencing wheat TaWIN1 and barley HvWIN1 could attenuate cuticular wax accumulation ( Kong and Chang, 2018 ; McAllister et al, 2022 ). Similarly, overexpressing OsWR1 , rice homologs of Arabidopsis AtSHN1 , improved while silencing OsWR1 attenuated wax biosynthesis in rice leaves ( Wang et al, 2012 ).…”