PpWRKY53 interacts with PpCML11 to enhance high temperature tolerance in sand pear fruit by regulating heat shock...

High temperature stress impairs sand pear fruit quality during ripening, often causing water-soaked browning. The roles of WRKY transcription factors in fruit thermotolerance remain unclear. Using transcriptomic analysis of short- and long-term heat-treated fruit, we identified a heat‑responsive WRKY gene, PpWRKY53. Its expression was strongly induced by high temperature, and the nuclear‑localized protein acted as a positive regulator. Transient overexpression of PpWRKY53 significantly reduced heat‑induced flesh browning, electrolyte leakage, H₂O₂, and MDA levels while maintaining higher firmness; silencing PpWRKY53 aggravated these stress phenotypes. Moreover, PpWRKY53 interacted with a calmodulin‑like protein, PpCML11. DAP-seq and dual-luciferase assays showed that PpWRKY53 bound to the PpHSP17.5-E promoter and activated the transcription of both PpHSP17.5-E and PpHSP17.5-M. When co-expressed with PpCML11 in tobacco leaves, PpWRKY53 enhanced the expression of PpHSP17.5-M, but did not significantly affect PpHSP17.5-E. However, when co-expressed in pear fruits, PpWRKY53 and PpCML11 together enhanced the expression of both PpHSP17.5-E and PpHSP17.5-M, and alleviated water-soaked browning, ROS accumulation, and MDA accumulation. Collectively, our findings reveal that PpWRKY53 functions as a key positive regulator that interacts with PpCML11 to activate downstream HSP expression, thereby enhancing high‑temperature tolerance in sand pear fruit. This study provides important genetic resources and a theoretical foundation for breeding heat‑tolerant sand pear varieties.