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

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 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.