BoaCRTISO regulates the color and glossiness of Chinese kale through its effects on pigment, abscisic acid, and cuticular wax biosynthesis

Carotenoid isomerase (CRTISO) is an important enzyme in carotenoid biosynthesis, and it catalyzes the conversion of lycopene precursors to lycopene in several plant species. However, the role of CRTISO in other biochemical processes during plant growth and development remains unclear. Here, we showed that Chinese kale boacrtiso mutants have distinctive characteristics, including a yellow-green hue and glossy appearance, and this contrasts with the dark green and glaucous traits observed in wild-type (WT) plants. Analysis of pigments in mutants revealed that the reduction in the content of carotenoids and chlorophylls contributed to the yellow-green coloration observed in mutants. An examination of cuticular waxes in Chinese kale indicated that there was a decrease in both the total wax content and the content of individual waxes in boacrtiso mutants (bearing a mutation of BoaCRTISO), which may be caused by the decrease of abscisic acid (ABA) content. The expression of carotenoid, chlorophyll, ABA, and wax biosynthesis genes was down-regulated in boacrtiso mutants. This finding confirms that BoaCRTISO regulates the biosynthesis of pigments, ABA, and cuticular waxes in Chinese kale. Our results provide new insights into the interplay between plant pigment and cuticular wax metabolic pathways in Brassica vegetables.