VvPIP1;1 plays a role in grape berry cracking by regulating water uptake

Fruit cracking is a persistent challenge for table grape growing. To investigate the mechanism of this disorder, a comprehensive two-year investigation was conducted to assess the fruit cracking percentage of 15 table grape (Vitis vinifera L.) varieties. Based on the findings, the cracking-susceptible variety ‘Xiangfei’ and the cracking-resistant variety ‘Zuijinxiang’ were selected for further study. Fruit growth curves for ‘Zuijinxiang’ and ‘Xiangfei’ were plotted based on fruit diameter and total soluble solids content, revealing that both varieties exhibited typical double-sigmoidal patterns that were highly similar. The period between 48 and 53 days after full bloom (DAFB) was identified as the critical phase for fruit cracking incidence. Furthermore, during the fruit cracking period, ‘Xiangfei’ fruit exhibited significantly higher water content and mesocarp cell area compared with those of ‘Zuijinxiang’. Applying aquaporin inhibitors (nano-silver) to ‘Xiangfei’ berries reduced fruit water uptake and cracking percentage, whereas applying aquaporin activators (forskolin) to ‘Zuijinxiang’ berries increased fruit water uptake and cracking percentage. Additionally, expression analysis of six genes associated with plasma membrane intrinsic proteins (PIPs) synthesis (VvPIP1;1, VvPIP1;2, VvPIP1;3, VvPIP2;1, VvPIP2;2, and VvPIP2;3) revealed that only the expression level of VvPIP1;1 was higher in ‘Zuijinxiang’ than in ‘Xiangfei’ during the fruit cracking period, whereas the expression levels of the other genes exhibited no significant difference between the two varieties. Transgenic overexpression of VvPIP1;1 in tomato resulted in increased fruit water content, enlarged mesocarp cell size, and enhanced fruit cracking percentage. These findings indicate that VvPIP1;1 plays a pivotal role in controlling grape berry cracking.