Integrated physiological, transcriptomic and metabolomic analyses of glossy mutant under drought stress in rapeseed (Brassica napus L.)

Rapeseed (Brassica napus L.), the second most important oil crop in the world, is extremely vulnerable to drought stress, resulting in severe reductions in yield and quality. Leaf epidermal wax plays an important role in drought stress. However, the genetic basis and regulatory mechanism of wax synthesis in B. napus remain unclear. Here, the integrated analysis of physiology, transcriptome, and metabolome was performed on a glossy mutant under drought stress to reveal the molecular basis of cuticular wax accumulation in rapeseed. Integrated transcriptomic and metabolomic analyses revealed the important roles of unsaturated fatty acids, wax biosynthesis, and plant hormone signal transduction in leaves for enhancing drought tolerance. Several candidate genes were identified to be involved in alkane synthesis and alcohol synthesis of the wax synthesis pathway, including CER1, MYB, FAR3, and MAH1, based on transcriptome and metabolome with weighted gene co-expression network analysis (WGCNA). And RT-qPCR also validated the expression patterns of these candidate genes in the glossy mutant under drought stress. This study provides new insights into the molecular mechanism of leaf epidermis wax synthesis and lays a foundation for breeding drought-resistant varieties and further functional research on the cuticular wax synthesis pathway in rapeseed.