Regulatory effects of exogenous calcium on sweet cherry fruit cracking and functional analysis of the PavCML42 gene

Rain‑induced fruit cracking during sweet cherry ripening severely restricts industry development, but whether calcium signaling regulates cracking through CML genes remains unclear. Using the crack‑prone cultivar 'Brooks', we investigated the physiological and molecular mechanisms of calcium‑mediated regulation through exogenous CaCl₂ spraying, physiological index measurements, transcriptome analysis, and gene function validation. Treatment with 0.5% CaCl₂ was most effective, reducing the cracking rate by 53.3%, decreasing MDA content, modulating antioxidant enzyme activities, and inhibiting cell wall hydrolase activities. Transcriptome analysis identified 18 calcium‑signaling‑related DEGs, among which PavCML42 showed the greatest differential expression. Tissue‑specific expression analysis revealed highest expression in roots and lowest in fruit. Transient overexpression of PavCML42 significantly increased cell wall hydrolase activities and induced cracking, whereas VIGS silencing reduced these enzyme activities and alleviated membrane lipid peroxidation damage. Overall, exogenous calcium mitigates fruit cracking by regulating PavCML42, which is involved in cell wall metabolism and the antioxidant system, providing a candidate gene for breeding crack‑resistant sweet cherry cultivars.