The synergistic effect of nitric oxide in Serendipita indica - induced resistance and basal immunity of wheat against powdery mildew

Aims：The occurrence of wheat powdery mildew caused by Blumeria graminis f. sp. tritici severely hampers the increase of wheat yield. The utilization of biological control in the management of powdery mildew is highly valuable due to its environmentally friendly and sustainable characteristics. The present study investigates the resistance mechanism against powdery mildew by employing a combination of inorganic small molecule NO and endophytic fungus Serendipita indica ( S. indica ). Methods：By spraying nitroprusside spraying (NO donor) on wheat leaves and inoculating of roots with S. indica , the effects of combined application of NO and S. indica on powdery mildew were determined through analysis of physiological and biochemical indexes, transcriptome and metabolome data. Results：Experimental data have demonstrated that pre-colonization with S. indica , followed by sodium nitroprusside spraying (NO donor), reduce 27.9% disease index caused by Blumeria graminis f. sp. tritici and elevate biomass by 20% in wheat. The synergistic application of both treatments (NO+ S. indica ) effectively enhancedchlorophyll content in leaves and relative water content in roots, significantly decreased the accumulation of malondialdehyde and electrical conductivity in leaves. Furthermore, this combination promotes antioxidant activity in wheat leaves through their synergistic effect. Transcriptome sequencing revealed that sodium nitroprusside alone did not induce a substantial number of differentially expressed genes; however, co-administration of NO and S. indica had a greater impact on transcriptomic changes. Differential expressed geneswere validated by fluorescence quantitative PCR analysis. Metabolic profiling indicated that co-application of NO and S. indica led to broader alterations across metabolic pathways. Notably, plant hormones such as gibberellin, auxin, and salicylic acid exhibited significant increases upon combined treatment. Conclusions：The study presents a novel research concept and tactic for the biological management of powdery mildew in wheat.