Grape Berry Splitting Is Correlated with Cell Wall Pectin Content and Cutin Composition.

Splitting of fleshy fruits causes substantial yield and economic losses in horticulture, yet the underlying physiological mechanisms remain poorly understood. This study investigated the epidermal cell wall and cuticular traits in six grapevine cultivars (Vitis vinifera L.) with a wide range of berry splitting susceptibility. Splitting was found to be unrelated to epidermal cell density and cuticle thickness. However, resistant cultivars exhibited higher cell wall pectin content at ripeness, suggesting its role in mitigating splitting. GC-MS profiling of grape berry cutin revealed a pronounced developmental shift in the aliphatic-to-phenolic monomers during ripening. Notably, resistant cultivars accumulated higher levels of phenolic monomers, including cinnamic acid-3,5-dimethoxy, methyl-3,4-dihydroxybenzoate, and C16:0 and C18:0 fatty acids, all of which were significantly associated with reduced splitting. Our findings highlight cell wall pectin content and cutin monomer composition as key determinants of grape berry splitting susceptibility and suggest molecular targets for reducing splitting in table grape cultivars.