The Phytophthora sojae RXLR effector Avh238 destabilizes soybean Type2 GmACSs to suppress ethylene biosynthesis and promote infection

• Published in: The New phytologist 2019-04, Vol.222 (1), p.425-437
• Main Authors: Yang, Bo, Wang, Yuyin, Guo, Baodian, Jing, Maofeng, Zhou, Hao, Li, Yufei, Wang, Haonan, Huang, Jie, Wang, Yan, Ye, Wenwu, Dong, Suomeng, Wang, Yuanchao
• Format: Article
• Language: English
• Subjects: Biosynthesis; Disease Resistance; Enzyme Stability; Ethene; Ethylene; Ethylenes - metabolism; Gene Silencing; Glycine max; Glycine max - immunology; Glycine max - metabolism; Glycine max - microbiology; Immunity; Infections; Innate immunity; Isoforms; Liquid chromatography; Lyases - metabolism; Mass spectrometry; Mass spectroscopy; Mutants; Mutation - genetics; Nicotiana - genetics; Nicotiana - microbiology; Nucleotides; Pathogens; Phytophthora; Phytophthora - physiology; Phytophthora sojae; Plant Diseases - microbiology; Plant immunity; Plants, Genetically Modified; Proteasome Endopeptidase Complex - metabolism; Protein Binding; Proteins; Proteins - metabolism; RXLR effector; Secretion; Soybeans; Type2 ACS; Virulence
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.15581

• Phytophthora pathogens secrete many effector proteins to manipulate host innate immunity. PsAvh238 is a Phytophthora sojae N-terminal Arg-X-Leu-Arg (RXLR) effector, which evolved to escape host recognition by mutating one nucleotide while retaining plant immunity- suppressing activity to enhance infection. However, the molecular basis of the PsAvh238 virulence function remains largely enigmatic. • By using coimmunoprecipitation and liquid chromatography-tandem mass spectrometry analysis, we identified the 1-aminocyclopropane-1-carboxylate synthase (ACS) isoforms, the key enzymes in ethylene (ET) biosynthesis, as a host target of PsAvh238. • We show that PsAvh238 interacts with soybean ACSs (GmACSs) in vivo and in vitro. By destabilizing Type2 GmACSs, PsAvh238 suppresses Type2 ACS-catalyzed ET biosynthesis and facilitates Phytophthora infection. Silencing of Type2 GmACSs, and inhibition of ET biosynthesis or signaling, increase soybean susceptibility to P. sojae infection, supporting a role for Type2 GmACSs and ET in plant immunity against P. sojae. Moreover, wild-type P. sojae but not the PsAvh238-disrupted mutants, inhibits ET induction and promotes P. sojae infection in soybean. • Our results highlight the ET biosynthesis pathway as an essential part in plant immunity against P. sojae and a direct effector target.