Suppressors of plant defense responses from wheat rust fungi
S. RAMACHANDRAN (1), C. Yin (2), J. Kud (3), K. Tanaka (2), S. Hulbert (2) (1) Washington State University, U.S.A.; (2) Washington State University, U.S.A.; (3) University of Idaho, U.S.A.

Fungi that cause cereal rust diseases (genus Puccinia) are important pathogens of wheat globally. Upon infection the fungus secretes a number of effector proteins that aid in the infection process. Although many putative effectors have been predicted using bioinformatic pipelines, the lack of available high throughput effector screening systems has stymied functional studies on these proteins. In this study, we mined the available transcriptomes of Puccinia graminis and Puccinia striiformis to look for potential effectors that suppress host hypersensitive response (HR), and twenty small (Nicotiana benthamiana and evaluated for their ability to suppress HR caused by four cytotoxic effector-R gene combinations and one mutated R gene Pto (Y207D). Nine out of the twenty proteins, designated Shr1- Shr9 (Suppressors of HR), were found to suppress HR in N. benthamiana. These effectors varied in the effector-R gene defenses they suppressed, indicating these pathogens can interfere with a variety of host defense pathways. In addition to HR suppression, one effector, Shr7, also suppressed PAMP-triggered immunity. This study presents a novel and feasible strategy for screening rust effectors in Nicotiana and provides the first evidence for presence of effectors in Puccinia species suppressing multiple plant defense responses.


Abstract Number: P17-592
Session Type: Poster