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Phytophthora infestans effector SFI 3 targets potato UBK to suppress early immune transcriptional responses

DOI: 10.1111/nph.15635 DOI Help

Authors: Qin He (Huazhong Agricultural University; University of Dundee (at JHI)) , Hazel Mclellan (University of Dundee (at JHI)) , Richard K. Hughes (John Innes Centre) , Petra C. Boevink (James Hutton Institute) , Miles Armstrong (University of Dundee (at JHI); James Hutton Institute) , Yuan Lu (Huazhong Agricultural University) , Mark J. Banfield (John Innes Centre) , Zhendong Tian (Huazhong Agricultural University) , Paul R. J. Birch (University of Dundee (at JHI); James Hutton Institute)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: New Phytologist

State: Published (Approved)
Published: December 2018
Diamond Proposal Number(s): 1219

Abstract: The potato blight agent Phytophthora infestans secretes a range of RXLR effectors to promote disease. Recent evidence indicates that some effectors suppress early pattern‐triggered immunity (PTI) following perception of Microbe‐Associated Molecular Patterns (MAMPs). Phytophthora infestans effector PiSFI3/Pi06087/PexRD16 was previously shown to suppress MAMP‐triggered pFRK1‐Luciferase reporter gene activity. How PiSFI3 suppresses immunity is unknown. We employed yeast‐two‐hybrid (Y2H) assays, co‐immunoprecipitation, transcriptional silencing by RNA interference and virus‐induced gene silencing (VIGS), and X‐ray crystallography for structure‐guided mutagenesis, to investigate the function of PiSFI3 in targeting a plant U‐Box‐kinase protein (StUBK) to suppress immunity. We discovered that PiSFI3 is active in the host nucleus and interacts in yeast and in planta with StUBK. UBK is a positive regulator of specific PTI pathways in both potato and Nicotiana benthamiana. Importantly, it contributes to early transcriptional responses that are suppressed by PiSFI3. PiSFI3 forms an unusual trans‐homodimer. Mutation to disrupt dimerization prevents nucleolar localisation of PiSFI3 and attenuates both its interaction with StUBK and its ability to enhance P. infestans leaf colonisation. PiSFI3 is a ‘WY domain’ RXLR effector that forms a novel trans‐homodimer which is required for its ability to suppress PTI via interaction with the U‐Box‐kinase protein StUBK.

Journal Keywords: potato late blight; pathogenicity; virulence; disease resistance; effector‐triggered susceptibility

Subject Areas: Biology and Bio-materials

Instruments: I02-Macromolecular Crystallography