Phytohormonal networks and thermomemory in plant heat stress tolerance: From mechanistic integration to precision engineering

Abstract

Rising global temperatures pose a major threat to crop productivity, requiring mechanistically informed, scalable strategies to enhance heat stress (HS) tolerance. Phytohormones are central regulators of plant HS responses; however, tolerance instead emerges from dynamic, context-dependent network behavior. This review provides a mechanism-oriented synthesis of how major phytohormones coordinate HS adaptation. Specifically, we (i) reframe phytohormone action through core regulatory modules, including redox control, carbon-energy allocation, reproductive stability, and growth–defense trade-offs; (ii) resolve phytohormonal crosstalk into functional interaction networks that determine stress outcomes; (iii) define the molecular basis of heat priming and thermomemory; and (iv) evaluate translational strategies, including genetic engineering, precision breeding, and advanced delivery systems, together with their limitations under field conditions. We propose a unifying conceptual model in which HS tolerance is an emergent property of hierarchical phytohormonal networks operating across fast signaling, transcriptional memory, and metabolic buffering layers. This framework shifts the focus from single-pathway manipulation toward precision “hormonomics” and network-level engineering, providing a systems-level platform for developing climate-proof crops in a future, hotter climate.