From the archives: Epidermal affairs—EVER links floral scent with cuticular waxes, while SPL9 and DEWAX connect them to diurnal regulation, and FIDDLEHEAD takes on a function in the epidermis

2023: EVERlasting perfume: EVER links floral scent with cuticular waxLike any living multicellular organism, plants have an outermost layer of cells known as the epidermis.The epidermis forms a boundary between plants and the external environment, and its cell walls are covered by a protective layer called the cuticle.This barrier, built from cutin polymers and waxes, confers several properties to plants, including water loss control, defense against biotic stresses, and gas transport facilitation (Arya et al. 2021).Research has hinted at a possible role of cuticle waxes with floral scent (Liao et al. 2021).Flower fragrances are the result of volatile compounds released into the environment through the cuticle.To get a better understanding of floral scent mechanisms, Skaliter et al. ( 2023) studied the transcriptomic profiles of the adaxial epidermis of Petunia (Petunia × hybrida) petals.As a result of their RNAseq analysis, the authors identified a gene they named EPIDERMIS VOLATILE EMISSION REGULATOR (EVER) to be highly expressed in the epidermis.Using a virus-based CRISPR/Cas9 system, the group generated petunia EVER Knockout (KO) lines, which displayed high volatile emissions.Strikingly, RNA seq analysis of the ever KOs did not display major changes in known volatile biosynthesis genes, but rather a severe enrichment in wax metabolism genes.Interestingly, though petunia ever KOs displayed altered epicuticular wax composition, no differences were observed in other cuticle properties such as its thickness or its water loss capacity.Therefore, ever KO leads to altered epicuticular wax profiles, affecting composition, and seemingly, the diffusion rates of different volatiles.