Metabolite and transcriptome reveal the lipid-associated key components and genes regulated by BoORP3a in ornamental kale.

Abstract

BoORP3a, an oxysterol-binding protein, located in the endoplasmic reticulum (ER), may function in cuticular wax deposition in ornamental kale. In this study, we investigated its regulation of the key components of cuticular wax and lipids, metabolic pathways, and potential target genes. HS-SPME/GC-MS identified 34 and 31 volatile organic compounds in wild-type and the BoORP3a-overexpressing plant OE-ORP3a-7, respectively, primarily including alkane, ketone, ester, and alcohol. Hentriacontane, 15-nonacosanone, and > C₂₀ alkanes were more abundant in OE-ORP3a-7, which may result in more cuticular wax in this plant. RNA sequencing identified 223 differentially expressed genes (DEGs) between wild-type and OE-ORP3a-7, comprising 119 upregulated and 104 downregulated DEGs. The KEGG enrichment analysis revealed that the downregulated DEGs in OE-ORP3a-7 were involved in glyoxylate and dicarboxylate metabolism, SNARE (Soluble N-ethylmaleimide-sensitive factor attachment protein receptor) interactions in vesicular transport, fatty acid biosynthesis, and glycerolipid metabolism; the upregulated DEGs were involved in steroid biosynthesis, fatty acid degradation, alpha-linolenic acid metabolism, and sphingolipid metabolism. Bo1g106990, Bo1g123670, and Bo9g166090 were identified as key DEGs in lipid-related pathways. We speculate that BoORP3a regulates several lipid metabolisms and may coordinate lipid turnover and remodeling. The results of this study will enrich the functionality of the ORPs family, provide new insights into plant wax research, and have significant implications for ornamental kale breeding.