Wheat Class III Peroxidase TaPOD70 Is a Potential Susceptibility Factor Negatively Regulating Wheat Resistance to f. sp. .

Powdery mildew, caused by f. sp. (), is one of the most important diseases on wheat worldwide and can lead to a large reduction in wheat production. Class III peroxidases (PODs), a kind of secretory enzyme and members of a multigene family in higher plants, have been linked to various plant physiological functions and defensive responses. However, the role of PODs in wheat resistance to remains unclear. , a class III POD gene, was identified from the proteomics sequencing of the incompatible interaction between wheat () cultivar Xingmin 318 and isolate E09. After transient expression of the TaPOD70-GFP fusion protein in leaves, TaPOD70 was located in the membrane region. Yeast secretion assay showed that TaPOD70 was a secretory protein. Furthermore, Bax-induced programmed cell death was inhibited by transient expression of in . The transcript expression level of was significantly upregulated in the wheat- compatible interaction. More crucially, knocking down using virus-induced gene silencing increased wheat resistance to compared with the control plants. In response to , histological analyses indicated that hyphal development of was significantly reduced, whereas HO production was enhanced in -silenced leaves. These findings imply that TaPOD70 may act as a susceptibility factor, adversely regulating wheat resistance to .