Abstract Given the groundbreaking progress in identifying unique functions of plant Hsp90 in stress responses in recent years, and the absence of systematic integration of these new mechanisms in protein quality control, hormone network regulation, chloroplast protection, and immune defense in existing reviews, this article aims to fill this gap. Recent studies have revealed four key mechanisms: (1) Hsp90 forms complexes with E3 ligases to promote polyubiquitination of heat-induced protein aggregates, cooperating with the 26S proteasome for clearance, a pathway hijacked by viruses; (2) Hsp90 stabilizes auxin receptor TIR1, reconstructs root auxin gradients via polarized PIN1, activates ABA biosynthesis, and enhances insect resistance through JA signaling; (3) Hsp90C maintains photosystem renewal, protects chloroplast DNA via CND1 translocation, and stabilizes thylakoid proteins via its CTE domain; (4) Hsp90 escorts CERK1 to initiate PTI, activates NLRs for ETI, and interacts with ATG8 to enhance autophagic pathogen clearance. This review integrates key new discoveries since 2012, and identifies core research gaps to address, namely regulation of Hsp90 abundance “optimal threshold”, its combined stress response mechanism, transformation of knowledge from model plants to major food crops, and provides a clear direction framework for subsequent research.
Wu et al. (2025) studied this question.