LhKCS17 delays senescence of cut lily and improves resistance to water-loss stress by promoting synthesis of petal wax

Epidermal wax covers the surface of plants and plays an important role in regulating plant growth and development and stress resistance. However, there are few reports on regulating wax synthesis of lily petals. In this study, β-ketoacyl-CoA synthase 17 (LhKCS17), a key enzyme in wax synthesis obtained from lily petals, was found to be located in the cytoplasm. Virus-induced gene silencing was applied to LhKCS17 in lily plants and the flowers senesced earlier, the cut flowers showed premature aging and decreased resistance to water loss, petal wax crystals were sparse, and the total wax content was reduced. When LhKCS17 was heterogeneously over-expressed in tomato and Arabidopsis thaliana, the OE-LhKCS17 tomato plants were larger than the wild type (WT), and the fruit peel shrinkage was significantly reduced during fruit storage, while waxy crystal density of the leaves and peel increased. The survival of OE-LhKCS17 A. thaliana under drought stress was significantly higher than that of WT, and the leaf wax crystals were denser than for WT. Further analysis of components and content of the epidermal wax in TRV2::LhKCS17 lily cut flower (petals), OE-LhKCS17 tomato (leaves and fruits), and OE-LhKCS17 A. thaliana (leaves) showed that changes in LhKCS17 expression level led to changes in the content of some wax components, mainly straight-chain alkanes (mainly C25 and C34), alkyl esters (mainly C27), and primary alcohols (mainly C30). Our results highlight the role of LhKCS17 in lily cut flowers in aging and water-loss stress, provide new insights into the synthesis of wax in the epidermis of lily petals, and lay a foundation for further investigation of other functions of this gene.