Abstract
Crop reproductive development represents the most heat-sensitive phase determining grain set and yield stability, yet the mechanisms by which reproductive tissues perceive, integrate, and respond to heat stress across multiple regulatory levels remain insufficiently understood. This review synthesizes recent advances in the molecular basis of reproductive-stage heat tolerance, focusing on the coordinated regulation of protein quality control mediated by heat shock proteins and heat shock transcription factors, phytohormone signaling networks, reactive oxygen species homeostasis, transcriptional regulation, and epigenetic reprogramming that collectively safeguard reproductive development under high-temperature stress. It further summarizes progress in translating these mechanistic insights into genetic improvement through the integration of quantitative trait locus mapping, candidate gene discovery, molecular markers, genomic selection, and genome editing. Despite these advances, major challenges remain, including the limited understanding of tissue-specific heat-response mechanisms in reproductive organs, insufficient resolution of cross-regulatory interactions among signaling pathways, and the lack of integrative frameworks linking multi-omics information with field-scale phenotypic performance. By integrating evidence across molecular, cellular, physiological, and genetic levels, this review proposes a systems-level framework for dissecting reproductive-stage heat tolerance and establishes a conceptual foundation for mechanism-guided breeding strategies to enhance crop resilience and yield stability under future climate warming.
