Cutin:cutin-acid endo-transacylase (CCT), a cuticle-remodelling enzyme activity in the plant epidermis

Abstract

Cutin is a polyester matrix mainly composed of hydroxy-fatty acids that occurs in the cuticles of shoots and root-caps. The cuticle, of which cutin is a major component, protects the plant from biotic and abiotic stresses, and cutin has been postulated to constrain organ expansion. We propose that, to allow cutin restructuring, ester bonds in this net-like polymer can be transiently cleaved and then re-formed (transacylation). Here, using pea epicotyl epidermis as the main model, we first detected a cutin:cutin-fatty acid endo-transacylase (CCT) activity. In-situ assays used endogenous cutin as the donor substrate for endogenous enzymes; the exogenous acceptor substrate was a radiolabelled monomeric cutin-acid, 16-hydroxy-[3H]hexadecanoic acid (HHA). High-molecular-weight cutin became ester-bonded to intact [3H]HHA molecules, which thereby became unextractable except by ester-hydrolysing alkalis. In-situ CCT activity correlated with growth rate in Hylotelephium leaves and tomato fruits, suggesting a role in loosening the outer epidermal wall during organ growth. The only well-defined cutin transacylase in the apoplast, CUS1 (a tomato cutin synthase), when produced in transgenic tobacco, lacked CCT activity. This finding provides a reference for future CCT protein identification, which can adopt our sensitive enzyme assay to screen other CUS1-related enzymes.

Comparative transcriptome provides insights into gene regulation network associated with the resistance to Fusarium wilt in grafted wax gourd Benincasa hispida

“…In addition, temporal analysis showed that genes with different expression trends between the graft and original wax gourds were significantly enriched in cutin, suberin, and wax biosynthesis ( Figures 5 , 6 ). Cutin is a major component of cuticle, which could protect the plant from biotic and abiotic stresses ( Xin et al., 2021 ). Cutin and suberin are hydrophobic lipid biopolyester components of the cell walls of specialized plant tissue and cell-types, where they facilitate adaptation to terrestrial habitats ( Philippe et al., 2020 ).…”

Unraveling Cuticle Formation, Structure, and Properties by Using Tomato Genetic Diversity

“…Gene expression profiling can be further combined with various multi-omics technologies, typically metabolome ( Fernandez-Moreno et al, 2016 ) and proteome ( Szymanski et al, 2017 ), and with large scale sequencing of genetic diversity ( Szymański et al, 2020 ) to assign putative functions to the genes and explore their role in cuticle formation. Novel functions revealed by biochemical approaches, e.g., the cutin:cutin-acid endo-transacylase (CCT) enzyme activity ( Xin et al, 2021 ), may also ultimately lead to the isolation of the encoding gene.…”