Abstract

High temperatures strongly suppress potato tuber formation, and the role of the phytohormone jasmonate (JA) in this temperature response remains unclear. Here, we demonstrate that JA positively regulates potato thermotolerance during tuber formation. When tuber formation-stage potato plantlets were exposed to elevated temperatures (30/26 °C, day/night) for three weeks, wild-type plants incurred a 25% yield loss. In contrast, JA-deficient irAOC lines exhibited enhanced heat sensitivity (45% yield loss), while JA-elevated irCYP94B3s lines displayed robust heat resistance (only 5% yield loss). Reciprocal grafting confirmed aerial tissue-derived JA is sufficient for this thermotolerance. During tuber initiation, heat stress reduced leaf JA accumulation, which correlated with upregulated expression of the tuberization repressor SP5G . This implies JA may facilitate tuberization under elevated temperature, likely by suppressing SP5G . Transcriptomic analysis and electrophoretic mobility shift assays suggested JA regulates SP5G transcription via a heat-responsive MYB transcription factor in the JA signaling pathway. Our findings establish JA promotes potato tuber formation under elevated temperatures and identify CYP94B3 family genes as targets for breeding thermotolerant potato cultivars.