Heat Shock Transcription Factors as Central Integrators of Plant Stress Responses: From Thermotolerance to Multi-Stress Resilience

Heat shock transcription factors (HSFs) have long been recognized for their essential role in mediating thermotolerance via the activation of heat shock proteins (HSPs). Recent studies, however, have significantly broadened this view, revealing that HSFs function as versatile transcriptional regulators orchestrating plant adaptation to a wide range of abiotic and biotic stresses. This review synthesizes current knowledge of HSF structure, activation, and canonical roles in the heat shock response, while emphasizing emerging insights into their diverse functions beyond heat stress. Evidence from both model and crop species demonstrates that many HSFs confer tolerance to a broad range of stresses, including drought, cold, salinity, oxidative stress, and pathogen attack, through intricate crosstalk with hormonal (e.g., ABA, SA, JA) and redox signaling pathways, as well as MAPK-mediated phosphorylation. We also discuss biotechnological strategies such as CRISPR/Cas-mediated genome editing, stress-inducible promoter engineering, and synthetic transcriptional circuits that offer promising avenues for fine-tuning HSF expression and enhancing multi-stress resilience in crops. A deeper understanding of HSF multifunctionality not only advances our comprehension of plant stress biology but also provides a foundation for engineering resilient crops in the context of global climate change.