Identification and Characterization of a Novel Protein Disulfide Isomerase Gene () from .

Protein disulfide isomerase (PDI) is a multifunctional enzyme that catalyzes rate-limiting reactions such as disulfide bond formation, isomerization, and reduction. There is some evidence that indicates that PDI is also involved in host-pathogen interactions in plants. In this study, we show that the rice root-knot nematode, , has evolved a secreted effector, MgPDI2, which is expressed in the subventral esophageal glands and up-regulated during the early parasitic stage of . Purified recombinant MgPDI2 functions as an insulin disulfide reductase and protects plasmid DNA from nicking. As an effector, MgPDI2 contributes to nematode parasitism. Silencing of by RNA interference in the pre-parasitic second-stage juveniles (J2s) reduced multiplication and also increased mortality under HO stress. In addition, an -mediated transient expression assay found that MgPDI2 caused noticeable cell death in . An intact C-terminal region containing the first catalytic domain (a) with an active motif (Cys-Gly-His-Cys, CGHC) and the two non-active domains (b and b') is required for cell death induction in . This research may provide a promising target for the development of new strategies to combat infections.