GRP7 is involved in Salicylic acid-mediated defense by its binding to SA-related transcripts
P. KIM (1), A. Joe (2), J. Alfano (1) (1) University of Nebraska, U.S.A.; (2) University of California, U.S.A.

Pseudomonas syringae uses a type III secretion system to inject type III effector proteins into plant cells to favor pathogenicity. A major role of type III effectors is the suppression of plant immunity. For that, the effectors target important immune components in host cells. The P. syringae pv. tomato DC3000 HopU1 type III effector is a mono-ADP-ribosyltransferase (ADP-RT) that modifies several Arabidopsis RNA-binding proteins including GRP7. GRP7 is known to be involved in PAMP-induced immune responses by interacting with pattern recognition receptor (PRR) RNA. Here, we show that plants over-expressing GRP7 are more resistant to biotrophic or hemibiotrophic pathogens and induce increased levels of PR genes after pathogen infection compared to wild-type plants. Importantly, we found that the increased resistance of plants over-expressing GRP7 is dependent on salicylic acid (SA)-mediated immunity. We found that GRP7 also binds other SA-related transcripts including SID2 and NPR1. The interaction of GRP7 with SID2 and NPR1 correlate with increased SA and NPR1 protein levels in plant over-expressing GRP7. The interaction between GRP7 and immunity-related RNA was inhibited by HopU1 in an ADP-RT activity-dependent manner. Our research reveals the broad role of GRP7 in plant immunity. It plays an especially important function in SA-dependent immune responses.We identified many more RNAs that bind GRP7 including many more immunity-related RNA with RNA immunoprecipitation (RIP) sequencing.

Abstract Number: P17-546
Session Type: Poster