Plant pathogens deliver different effector proteins into plant cells to inhibit host immune responses. Because the effectors are thought to target important immune factors in plant cells, screening for host factors that interact with the effectors is a useful approach to discover uncharacterized immune factors. In fact, many immune factors have already been identified as targets of effectors. We isolated a rice receptor-like cytoplasmic kinase OsRLCK185 as an interactor with Xanthomonas oryzae effector Xoo1488. OsRLCK185 is directly phosphorylated by the immune receptor OsCERK1, and transmits immune signals to downstream components to induce a series of immune responses including MAPK activation.
The pathogenicity and mycological aspects of blast fungi isolated from Festuca arundinacea in Miyagi Prefecture, northern Japan, were studied. They typically formed elliptical lesions with pointed ends, a whitish-grey center and reddish-brown margin on their host and on Italian ryegrass, but they did not form lesions on rice or crabgrass. They produced the dihydropyriculol, but not the pyrichalasin H which is characteristic toxin of crabgrass blast fungi. The RFLP band patterns of the β-tubulin gene from the isolates corresponded to those of Pyricularia oryzae; no products were amplified by Digitaria-specific primers. Thus, isolates from F. arundinacea were assessed to be P. oryzae.