Advances in Physiological and Molecular Mechanisms of Heat Stress in Apple and Pear

Persistent global warming significantly impacts crop phenology and productivity, with perennial fruit trees facing heightened challenges due to their long life cycles and complex heat stress accumulation. Apple and pear, which hold substantial economic and nutritional value, are particularly vulnerable to high temperatures, manifesting as accelerated phenology, impaired floral organ development, disrupted pollination and fertilization, and insufficient fruit coloration—all of which severely compromise fruit quality and commercial value. Although recent advances have been made in elucidating heat stress signal transduction and regulatory networks in model plants such as Arabidopsis and rice, research on heat stress responses in apple and pear remains limited. This review systematically synthesizes the physiological responses, gene expression regulation, and protective cultivation strategies under high-temperature stress in apple and pear, aiming to provide a theoretical foundation for thermotolerance breeding and the establishment of heat stress regulatory networks, thereby supporting sustainable production in the context of global warming.