Transcriptome-Metabolome Integration Identifies AdOPR3 and AdCYP707A4 as Regulators of Opposing Jasmonic Acid and Abscisic Acid Dynamics in Ripening Kiwifruit

Kiwifruit (Actinidia deliciosa) contributes >4 million tons to global fruit production annually and ranks among the highest dietary sources of vitamin C and bioactive polyphenols. Its quality is mainly influenced by the coordinated regulation of essential metabolites during fruit ripening. Although several important metabolites associated with fruit color, flavor, and nutrition have been elucidated, the dynamic changes and regulatory networks of ripening-associated metabolites remain largely unexplored. In this study, comprehensive metabolic dynamics of developing fruit of Actinidia deliciosa cv. Xuxiang (‘XX’) were investigated through a widely targeted metabolomic analysis. Three metabolites associated with hormone metabolism showed that differentially accumulated 12-oxo-phytodienoic acid (12-OPDA) and jasmonic acid (JA) were downregulated, while abscisic acid (ABA) was upregulated in XX9 vs. XX21, with a Log2|fold change| of −1.96, −3.09, and 1.76, respectively. Two hub genes (AdOPR3 and AdCYP707A4) were then screened based on integrative analyses of metabolome and transcriptome data, and showed significantly decreased expression during ‘XX’ fruit ripening, which might be responsible for the reduced content of JA and enhanced level of ABA, respectively. Furthermore, co-expression networks of AdOPR3 and AdCYP707A4 were constructed by WGCNA and the potential transcriptional regulators of these two hub genes were predicted based on a correlation threshold over 0.9. Taken together, these results revealed the opposing accumulation patterns of JA and ABA might contribute to physiological ripening in kiwifruit, via the TF-mediated transcriptional regulation of AdOPR3 and AdCYP707A4. These findings provide insights for hormonal control of fruit ripening.