Molecular Chaperone Networks in Plants: Maintaining Proteostasis and Enhancing Stress Resilience for Crop Improvement.

Molecular chaperones play a central role in the plant proteostasis machinery by aiding the folding of nascent proteins, preventing aggregation, and repairing or degrading damaged proteins. These functions are especially essential during abiotic and biotic stress, which can destabilise cellular proteins and disrupt metabolic homoeostasis. This review summarises the current progress regarding the major heat shock protein (Hsp) families, Hsp100, Hsp90, Hsp70, Hsp60, and small heat shock proteins (sHSPs) and their key co-chaperones, DnaJ/Hsp40 and nucleotide exchange factors (NEFs), in relation to their structural characteristics, subcellular targeting, and heat shock factor (HSF)-mediated regulatory pathways. We emphasise certain examples, such as the role of Hsp101 in acquired thermotolerance or the use of sHsps as ATP-independent aggregation preventers. Transcriptional, proteomic, and interactomic analyses have shown changes in chaperone abundance and activity during stress, but there is a major gap in the understanding of how chaperone networks respond to combined, field-relevant stress. Recent biotechnological uses, such as CRISPR/CAS9-based knockout of OsHSBP1 in rice and transgenic overexpression of TaHSP17.4 in wheat, show concrete support of stress tolerance and stability in yield. Combining biochemical processes with the emerging biotechnological understanding, this review highlights how the manipulation of chaperone networks can be targeted to enhance the pace at which crops, capable of withstanding climate change, can be developed, and assist in supporting the sustainable productivity of agriculture.