WAX INDUCER 1 Regulates β-Diketone Biosynthesis by Mediating Expression of the Cer-cqu Gene Cluster in Barley

Abstract

Plant surface properties are crucial determinants of resilience to abiotic and biotic stresses. The outer layer of the plant cuticle consists of chemically diverse epicuticular waxes. The WAX INDUCER1/SHINE subfamily of APETALA2/ETHYLENE RESPONSIVE FACTORS regulates cuticle properties in plants. In this study, four barley genes homologous to the Arabidopsis thaliana AtWIN1 gene were mutated using RNA-guided Cas9 endonuclease. Mutations in one of them, the HvWIN1 gene, caused a recessive glossy sheath phenotype associated with β-diketone deficiency. A complementation test for win1 knockout (KO) and cer-x mutants showed that Cer-X and WIN1 are allelic variants of the same genomic locus. A comparison of the transcriptome from leaf sheaths of win1 KO and wild-type plants revealed a specific and strong downregulation of a large gene cluster residing at the previously known Cer-cqu locus. Our findings allowed us to postulate that the WIN1 transcription factor in barley is a master mediator of the β-diketone biosynthesis pathway acting through developmental stage- and organ-specific transactivation of the Cer-cqu gene cluster.

Decoding drought resilience: a comprehensive exploration of the cotton Eceriferum (CER) gene family and its role in stress adaptation

“…The CER gene family contributes to the production of cuticle wax and has a vital function in stress mitigation [ 12 ]. The CER gene family has been found across the genome in a range of plant species, including Castanea mollissima [ 32 ], apple [ 29 ] and passion fruit ( Passiflora edulis ) [ 31 ], and functionally described in (A) thaliana [ 43 ], Barley [ 44 ], Brachypodium distachyon [ 45 ], and (B) napus [ 46 ]. However, the CER genes in cotton ( G. hirsutum ) have not yet been studied.…”

Germination and Growth Characteristics of nud Knockout and win1 Knockout Barley Lines under Salt Stress

“…The nud KO lines are known to have lower root weight and shorter length relative to win1 KO lines under normal conditions [28]. It has been reported that at later stages of development, nud KO and win1 KO lines do not differ from the WT line in key growth characteristics, except for a reduction in 1000-grain weight in hull-less nud KO lines, which has been attributed to the absence of lemmas [13,14,28].…”

“…Previously, two-row spring barley (H. vulgare L.) cv. GP has been chosen as donor material for targeted mutagenesis (inactivation) of genes HvNUD [13] and HvWIN1 [14] by means of the Cas9/gRNA system. In the present work, to assess salt tolerance of the obtained KO barley plants, three nud KO lines (nud 01-4, nud 05-4, and nud 07-1) and three win1 KO lines (win1 17-4-14, win1 25-2-2, and win1 25-2-18) were utilized, each carrying different mutation types (deletion, insertion, or their combinations).…”

“…A knockout (KO) of the HvNUD gene leads to the transformation of hulled to naked barley [13]. Plant mutants in the HvWIN1 gene are characterized by a deficiency of epicuticular wax load on the surface of leaves, stems, and spikes in the generative phase of development [14]. The cuticle is considered a key evolutionary acquisition in terrestrial plants and protects them from various abiotic and biotic factors such as high and low temperatures, drought, UV radiation, salinity, and the impact of bacteria, fungi, and viruses [15].…”

“…KO lines serve as ideal models for researching effects of gene mutations, including pleiotropic effects [35,36]. Suitable previously generated KO lines called nud [13] and win1 [14] were chosen here as models for assessing salt tolerance. We hypothesized that the KO lines would differ in salt tolerance judging by growth characteristics as compared to a wild-type (WT) barley line (control).…”