Speaker — Guo-Liang Wang, Associate Chair and Professor in the Department of Plant Pathology at The Ohio State University

Title — Ubiquitination meets phosphorylation to regulate programmed cell death and innate immunity in rice

Abstract — Ubiquitination and phosphorylation are two important post-translational modifications (PTMs) in plants. How these two PTMS coordinately regulate programmed cell death and innate immunity in plants is still obscure. We previously used the rice lesion mimic mutant spl11 to study the molecular basis of programmed cell death and innate immunity. SPL11 encodes an E3 ubiquitin ligase that is a negative regulator of cell death and broad-spectrum resistance to two rice pathogens. SPL11 interacts with the Rho GTPase-activating protein (RhoGAP) SPIN6, which negatively regulates the Rho GTPase OsRac1, a central regulator of immune responses. Recently, we cloned the SPL11 cell-death suppressor 2 (SDS2) gene that encodes an S-domain monocot-specific receptor-like kinase. Genetic analysis showed that SDS2 is a positive role in rice immunity. Interestingly, SDS2 interacts with and phosphorylates SPL11, which in turn ubiquitinates SDS2 for degradation. In addition, SDS2 interacts with receptor-like cytoplasmic kinases, OsRLCK118/176, that phosphorylate the NADPH oxidase OsRbohB to positively regulate immunity. Candidate genes that are involved in the SDS2 signaling pathway have been obtained using yeast-two hybrid screens, transcriptomic, phosphoproteomic and metabolomic approaches. Our study demonstrated the importance of both SPL11-mediated ubiquitination and SDS2-mediated phosphorylation and their interplay in rice cell death and immunity.

Host — Joe Aung