Biochemical markers for grape berry splitting resistance: prospects for targeted breeding

Abstract

Berry splitting is a major physiological disorder in fleshy fruits that undermines quality, yield, and shelf life. In table grapes (Vitis vinifera L.), susceptibility to splitting is a primary cause of sour rot disease, resulting in significant commercial and economic losses.

Due to the lack of effective agrotechnical practices to prevent grape berry splitting, breeding split-resistant cultivars is a priority objective in modern viticulture. However, genetic progress is constrained by a lack of reliable biochemical markers and a limited understanding of the structural and chemical mechanisms governing this trait.

This study addresses the knowledge gap by evaluating six distinct table grape cultivars grown under identical environmental conditions that exhibit a wide range of splitting susceptibility. Through comprehensive histological and biochemical analyses, we quantified skin epidermal cell density, cell wall polysaccharides, and cuticle thickness. We found that neither epidermal cell density nor cuticle thickness was associated with splitting susceptibility. Instead, cell wall pectin content was the only polysaccharide to exhibit a significant negative correlation with splitting, suggesting its potential role in mitigating the disorder by enhancing exocarp structural integrity.

Furthermore, utilizing GC MS analysis, we performed the first comprehensive profiling of grape berry cutin monomers. This analysis uncovered a dynamic, developmentally regulated metabolic shift in cutin biosynthesis, characterized by a transition from aliphatic components in early development to a predominance of phenolic monomers during the ripening stage.

Notably, the accumulation of specific phenolic monomers, especially cinnamic acid-3,5-dimethoxy and methyl-3,4-dihydroxybenzoate, alongside C16 and C18 fatty acids, was significantly associated with enhanced splitting resistance. These findings highlight cell wall pectin content and cutin monomer composition as key determinants of grape splitting susceptibility. These biochemical traits offer promising new selectable markers and provide clear molecular targets for developing resilient table grape cultivars.