Genome-Wide Characterization of Kiwifruit Invertase Gene Family Reveals Roles of AcCWINV4 in Sugar Accumulation and Cold Tolerance

Invertase, a core catalyst in sugar metabolism, irreversibly hydrolyzes sucrose into hexoses, establishing the fundamental biochemical pathway for carbon allocation in plants and playing pivotal roles in plant growth development, fruit quality regulation, and stress response. In the present study, we identified a total of 25 invertase genes from the kiwifruit (<i>Actinidia chinensis</i> cv Hongyang) genome and systematically analyzed the physicochemical properties, chromosomal localization, genomic features, and gene evolution patterns of the <i>AcINV</i> family. The evaluation of selection pressure indices robustly demonstrated that the <i>INV</i> family underwent purification selection during domestication. Furthermore, based on the correlation between gene expression levels during the post-harvest ripening stage of kiwifruit and soluble sugar content, we identified the potential gene <i>AcCWINV4</i> as being associated with sugar accumulation. Furthermore, virus-induced gene silencing (VIGS) of <i>AcCWINV4</i> confirmed its functional role in fruit sugar accumulation and plant response to cold stress. This study provides critical theoretical support for breeding cold-tolerant and high-quality kiwifruit varieties using molecular biological methods.