Integrated multi-omics analysis reveals candidate genes for cuticular wax biosynthesis and molecular characteristics of a glossy mutant in rapeseed under natural drought stress
TL;DR
Results suggest that the drought response in the glossy mutant involves not only a defective cuticular barrier but also extensive metabolic and signaling reprogramming, which offers a promising approach for developing more sustainable farming methods amid environmental challenges.
Abstract
Introduction Cuticular wax plays a crucial role in drought tolerance. However, the regulatory mechanisms controlling cuticular wax biosynthesis and the drought response in rapeseed are not well understood. Methods and Results In this study, we identified a glossy mutant, hy7201, in rapeseed (Brassica napus L.). Compared to the wild-type ‘HY7201’, hy7201 exhibited a significant reduction in total cuticular wax content, altered composition, and decreased crystal density, along with a significant increase in cuticle permeability. Genetic analysis revealed that the glossy phenotype of the hy7201 mutant is controlled by a single dominant gene. Through bulked segregant analysis coupled with next-generation sequencing (BSA-seq) of waxy and glossy pools derived from F1 individuals of the self-crossed hy7201 population, BnaA09G0721400ZS, the homolog gene of AtCER1, was identified as a key candidate gene. This gene encodes a very-long-chain aldehyde decarbonylase, which contributes to the differences in leaf cuticular wax accumulation between the wild-type ‘HY7201’ and the glossy mutant ‘hy7201’. To validate the key genes involved in cuticular wax biosynthesis and characterize the molecular features under natural drought conditions in glossy plants, we performed an integrated analysis of the leaf transcriptome, proteome, and metabolome using KEGG enrichment, Pearson correlation, and two-way orthogonal partial least squares (O2PLS) methods with three biological replicates. The genes CER1 (BnaA09G0721400ZS) and its paralog CER1-2 (BnaA09G0698500ZS) were significantly downregulated at both the transcriptional and protein levels. Additionally, they exhibited significant negative correlations with differentially expressed metabolites (DEMs) in glossy plants under drought stress. The multi-omics approach uncovered that pathways related to cutin, suberin, and wax biosynthesis, as well as ABC transporters, glucosinolate biosynthesis, glutathione metabolism, linoleic acid metabolism, sphingolipid metabolism, and arginine and proline metabolism, significantly contribute to the glossy plant’s response to drought. Discussion These results suggest that the drought response in the glossy mutant involves not only a defective cuticular barrier but also extensive metabolic and signaling reprogramming. This insight could facilitate the identification of genes related to cuticular wax biosynthesis and drought stress response, which could be utilized in molecular breeding programs to enhance drought tolerance in rapeseed. Consequently, this offers a promising approach for developing more sustainable farming methods amid environmental challenges.