BrWax1 function in wax biosynthesis was verified by allelic mutations in Chinese cabbage

The primary function of cuticular wax is to prevent non-stomatal water loss, while the wax deficiency conferring a glossy appearance on plants is conductive to crop commodity qualities. We previously mapped a wax-deficient gene BrWax1 in a natural mutant ‘08A235-2’ by SSR marker, and predicted Bra013809 (BrWax1) as the candidate gene in Chinese cabbage (Brassica rapa L. ssp. pekinensis). In order to verifying the function of BrWax1, two allelic wax-crystal deficiency mutants wdm4 and wdm8 from an EMS mutagenesis population of Chinese cabbage were screened. wdm4 was applied to identify the mutant gene, with the finding that BraA01g015290.3C, the homologous of AT4G24510 (AtCER2), was the candidate gene. Bra013809 in Brara_Chiifu_V1.5 and BraA01g015290.3C in Brara_Chiifu_V3.0 were annotated as the same gene in Brassicaceae Database. A SNP (C to T) on BrWax1 in wdm4 resulted in a stopgain, and a SNP (G to A) on BrWax1 in wdm8 led to the deletion of 38 bases which caused a stopgain at the 190^th amino acid. These results finally verified the function of BrWax1 in the wax biosynthesis. Our findings emphasize the crucial role of the BrWax1 gene in cuticular wax biosynthesis in Chinese cabbage and suggest its potential as a valuable genetic resource for breeding for glossy appearance.