The miR168a-TaAGO1b module improves Fusarium head blight resistance and yield in wheat

Fusarium head blight (FHB) is a devastating fungal disease of wheat that causes severe yield loss and mycotoxin contamination. Wheat varieties offering higher grain yield while maintaining moderate resistance to FHB are highly desirable. Here, we report that microRNA168a (miR168a) acts as a key negative regulator of both FHB resistance and grain yield in wheat. Knockdown of miR168a via target mimicry (MIM168) enhanced resistance to FHB in transgenic plants, accompanied by increased H₂O₂ accumulation and restricted fungal spread. MIM168 plants also exhibited higher grain yield with longer spikes and higher spikelet number per spike under uninfected field conditions. By contrast, miR168a overexpression (OE168) lines became more susceptible to FHB and displayed significantly reduced grain yield. We further identified TaAGO1b as a target of miR168a. Knockout of TaAGO1b using CRISPR/Cas9 (ago1b) recapitulated the FHB susceptibility and reduced spike length, demonstrating that miR168a and TaAGO1b work as a module. Moreover, miR168a positively regulates the miR156-TaSPL17 module, which is associated with spike development, and it also regulates miR444 in FHB infection, and that knockdown of miR444 via target mimicry (MIM444) enhances FHB resistance. Meanwhile, ago1b mutations upregulated miR156 and miR444. Thus, our data demonstrated that the miR168a-TaAGO1b module contributes to wheat spike architecture and FHB resistance via miR156 and miR444, providing a potential strategy for breeding high-yielding and FHB-resistant wheat varieties.