|Dardick, Christopher - Chris|
Submitted to: Molecular Plant
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2008
Publication Date: 5/1/2008
Citation: Peng, Y., Bartley, L.E., Chen, X., Dardick, C.D., Ruan, R., Canlas, P.E., Ronald, P.C. 2008. OsWRKY62 is a negative regulator of basal and Xa21-mediated defense against Xanthomonas oryzae pv. oryzae in rice. Molecular Plant. 1(3):446-458. Interpretive Summary: Plants protect themselves against pathogen invasion by turning on specific cellular defense responses. Upon exposure to the bacterial pathogen, Xanthomonas oryzae, rice plants carrying the disease resistance gene Xa21 turn on a specific set of defenses that limit the growth of the bacteria. Currently, very little is known about how the Xa21 gene recognizes and responds to this bacterial pathogen. Here, we report the discovery of a gene called OsWRKY62 that controls the ability of Xa21 to turn on defense responses. WRKY-type genes are known to regulate plant defense responses but have never been directly linked to the genes that actually recognize the invading pathogen. OsWRKY62 directly interacts with Xa21, and when OsWRKY62 activity is increased, the plants become highly susceptible to infection by Xanthomonas. The discovery of OsWRKY62 fills a key gap in our understanding of how plant disease resistance genes respond to pathogen infection and may serve as a potential target for engineering resistance against pathogens.
Technical Abstract: The rice Xa21 gene, which confers resistance to the bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo), encodes a receptor-like kinase. Few components involved in transducing the Xa21-mediated defense response have yet been identified. It is reported that XA21 binds to a WRKY transcription factor, called OsWRKY62. OsWRKY62 encodes two splice variants (OsWRKY62 and OsWRKY62spl). OsWRKY62:smGFP2 fusion proteins partially localize to the nucleus. Transgenic plants overexpressing OsWRKY62 are compromised in the basal defense response and Xa21-mediated resistance to Xoo. Furthermore, overexpression of OsWRKY62 suppresses the activation of defense-related genes. These results indicate that OsWRKY62 functions as a negative regulator of innate immunity in rice and serves as a critical mediator of both basal and race-specific defense responses.