Functional Characterization of the Wheat Macrophage Migration Inhibitory Factor TaMIF1 in Wheat-Stripe Rust (Puccinia striiformis) Interaction

Macrophage migration inhibitory factor (MIF), named for its role in inhibiting macrophage/monocyte migration, has multiple functions in modulation of inflammation, cell proliferation, angiogenesis, and tumorigenesis in vertebrates. Although homologs of this gene can be found in plants, the function of MIF in plants remains obscure. Here, we characterized TaMIF1 in Triticum aestivum resembling the MIF secreted from Homo sapiens. Transcript analysis revealed that TaMIF1 responded to stripe rust infection of wheat and was upregulated during the infection stage. TaMIF1 was localized to both the cytosol and nuclei in wheat mesophyll protoplast. Additionally, TaMIF1 possessed significant tautomerase activity, indicating conservation of MIFs across kingdoms. Agrobacterium tumefaciens infiltration assay demonstrated that TaMIF1 was capable of suppressing programmed cell death hinting its role in plant immunity. Heterologous expression of TaMIF1 increased fission yeast sensitivity to oxidative stress. Silencing TaMIF1 decreased the susceptibility of wheat to Pst seemingly through increasing reactive oxygen species accumulation. In conclusion, functions of the TaMIF1 were investigated in this study, which provides significant insight into understanding the role of MIFs across kingdoms.