Abstract

Drought affects over 60 % of wheat cultivation areas and reduces wheat yields considerably. To ensure global food security, it is imperative to decode the molecular basis of wheat drought tolerance and adaptation. In this study, we characterized a drought‑inducible heat shock transcription factor, designated TaHsfA18. Overexpression of TaHsfA18 markedly enhanced seedling survival under drought conditions, water retention, and post-drought recovery, whereas CRISPR/Cas9-mediated mutation caused heightened sensitivity to drought. We found that TaHsfA18 promoted the accumulation of osmolytes such as proline and soluble sugars and mitigated oxidative damage, as evidenced by lower levels of H 2 O 2 and malondialdehyde. TaHsfA18 directly bound to a Heat Shock Element in the promoter of TaERF073 , repressing its transcription and thereby alleviating its suppression of stress-adaptive pathways. In field trials, TaHsfA18-OE lines showed superior performance in terms of photosynthetic rate, water use efficiency, and grain yield under drought conditions. We determined that the Hap-4B-A haplotype of TaHsfA18 is associated with increased spikelet number per spike and could be useful for marker-assisted selection. Together, our data demonstrate that TaHsfA18 is an important integrator of osmotic and oxidative stress responses that shows promise as a target for engineering drought-tolerant wheat varieties.