Identification of A Phytophthora parasitica RXLR effector that associates with Arabidopsis thaliana NPR1 to promote infection
M. ZHANG (1), Q. Li (1), Q. Zhang (2), W. Li (1), Y. Chen (1), D. Dou (3) (1) Nanjing Agricultural University, China; (2) Nanjing Agricultural University, China; (3) Nanjing Agricultural Univresity, China

Phytopathogens secrete effector proteins into host cell to promote infection. The salicylic acid (SA) signaling pathway confers resistance to biotrophic and hemibiotrophic phytopathogens. Some effectors from oomycete and fungal pathogens interfere with salicylic acid (SA) synthesis to suppress plant defense responses. However, it is still unknown whether plant pathogens can directly target the central regulator NPR1 (non-expresser of pathogenesis related gene1) in SA immune signaling to suppress plant defense. Here we showed that the Phytophthora parasitica RXLR effector, PpNIE, (P. parsitica NPR1-interacting effector), interacts with NPR1 by yeast two-hybrid screening. The interaction was further confirmed by co-immunoprecipitation in planta. Silencing PpNIE in P. parasitica significantly reduced pathogen virulence in Nicotiana benthamiana and Arabidopsis thaliana. Transient expression of PpNIE in N. benthamiana promoted plant susceptibility to Phytophthora pathogens. These results indicate that PpNIE is involved promoting Phytophthora virulence. Interestingly, virulence of the PpNIE-silenced transformants was recovered in the npr1 Arabidopsis mutant compared to wild-type Col-0, implying that PpNIE's primary virulence target is NPR1. The molecular mechanisms underlying how PpNIE interferes with NPR1 function will be further studied. 

Abstract Number: P9-330
Session Type: Poster