Suboptimal pre-anthesis water status mitigates wheat susceptibility to fusarium head blight and triggers specific metabolic responses

The impact of abiotic challenges on plant physiology reshapes plant-pathogen interactions by modulating the plant immune responses. In wheat, the development of Fusarium Head Blight (FHB) is heavily influenced by environmental conditions, especially during the pre-anthesis stage, just before fungal infection occurs. The early stages of infection are thus likely conditioned by prior environmental changes with consequences on the disease outcome that require further characterization. In this study, we aimed to assess the impact of pre-anthesis water depletion followed by rapid rehydration at inoculation on the expression of FHB-related molecular determinants with emphasis on susceptibility factors and metabolism-related processes. Water depletion altered plant physiology and its effects remained detectable after three days after rehydration, leading to significantly reduced FHB symptoms. Dual-transcriptomics, combined with untargeted metabolomics, revealed two key findings including (i) extensive metabolic changes specific to prior water stress, and (ii) the strong conservation of previously identified candidate susceptibility genes regulation. Considering the combined stress effects, a unique response signature emerged, highlighting that immune responses are strongly interwoven with physiological adjustments. Our findings provide new insights into the trade-offs that plants make under multiple challenges and identify original wheat metabolic determinants that may improve FHB resistance even in suboptimal physiological conditions.