A cascade of BoABF2-BoMYB96/BoMIEL1 regulates wax accumulation in kale.

Cuticular wax is composed of a variety of very-long-chain fatty acids (VLCFAs) and their derivatives, such as alkanes, aldehydes, alcohols, ketones, and esters. The presence of wax crystals not only determines the glossy or dull appearance of leaf surfaces, but also plays an important role in protecting plants against abiotic and biotic stresses, including drought, ultraviolet exposure, cold, salinity, and pathogen or insect attacks. Kale (Brassica oleracea var. acephala), an important horticultural crop, displays distinct levels of wax crystal coverage on its leaves. To investigate the genetic basis of this trait, an F2 population was constructed from a cross between the lines 'S0836' and '6BZ'. Individuals with extremely high and low wax contents were selected to form wax and bright extreme bulks, which were subjected to whole-genome resequencing and bulk segregant analysis to map quantitative trait loci (QTLs) associated with wax accumulation. This population provides a valuable resource for studying wax biosynthesis and for breeding kale varieties with improved drought resistance.