Fruit cuticle composition influences susceptibility of peach (Prunus persica) fruit to brown rot (Monilinia fructicola)

Brown rot, caused by Monilinia spp., is the most significant disease affecting stone fruits, including Prunus persica (peach). In Europe, Monilinia fructicola and Monilinia laxa are the primary species responsible for the disease, with M. fructicola becoming dominant in the Ebro Valley, a major peach production area in Spain. The fruit cuticle serves as the first line of defense against external threats and may play a key role in determining susceptibility to Monilinia spp. This study investigated the influence of fruit cuticular components (both cuticular waxes and cutin) on the susceptibility to M. fructicola in 21 Spanish P. persica cultivars, with a variable susceptibility to Monilinia spp., from the National Peach Collection at CITA (Zaragoza, Spain). The results indicate that both cuticular waxes and the cutin matrix significantly influence fruit susceptibility to M. fructicola. Specifically, several cuticular wax compounds, including pentacyclic triterpenoids and very-long-chain alkanols, as well as certain cutin monomers, were strongly negatively correlated with susceptibility to M. fructicola. These findings underscore the crucial role of cuticular components in fruit defense against M. fructicola and suggests that introgression of these traits could help breed cultivars with reduced susceptibility to Monilinia spp.