title: Phytophthora infestans effector AVRblb2 prevents secretion of a plant immune protease at the haustorial interface.
abstract: In response to pathogen attack, plant cells secrete antimicrobial molecules at the site of infection. However, how plant pathogens interfere with defense-related focal secretion remains poorly known. Here we show that the host-translocated RXLR-type effector protein AVRblb2 of the Irish potato famine pathogen Phytophthora infestans focally accumulates around haustoria, specialized infection structures that form inside plant cells, and promotes virulence by interfering with the execution of host defenses. AVRblb2 significantly enhances susceptibility of host plants to P. infestans by targeting the host papain-like cysteine protease C14 and specifically preventing its secretion into the apoplast. Plants altered in C14 expression were significantly affected in susceptibility to P. infestans in a manner consistent with a positive role of C14 in plant immunity. Our findings point to a unique counterdefense strategy that plant pathogens use to neutralize secreted host defense proteases. Effectors, such as AVRblb2, can be used as molecular probes to dissect focal immune responses at pathogen penetration sites.
authors.affiliation: The Sainsbury Laboratory,  Norwich Research Park, Norwich NR4 7UH, United Kingdom.
authors.forename: Tolga O
authors.initials: TO
authors.lastname: Bozkurt
authors.forename: Sebastian
authors.initials: S
authors.lastname: Schornack
authors.forename: Joe
authors.initials: J
authors.lastname: Win
authors.forename: Takayuki
authors.initials: T
authors.lastname: Shindo
authors.forename: Muhammad
authors.initials: M
authors.lastname: Ilyas
authors.forename: Ricardo
authors.initials: R
authors.lastname: Oliva
authors.forename: Liliana M
authors.initials: LM
authors.lastname: Cano
authors.forename: Alexandra M E
authors.initials: AM
authors.lastname: Jones
authors.forename: Edgar
authors.initials: E
authors.lastname: Huitema
authors.forename: Renier A L
authors.initials: RA
authors.lastname: van der Hoorn
authors.forename: Sophien
authors.initials: S
authors.lastname: Kamoun
mesh_terms: D060054:Agrobacterium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D007107:Immune System; D018613:Microscopy, Confocal; D008954:Models, Biological; D010447:Peptide Hydrolases / Q000235:genetics*; D055750:Phytophthora infestans / Q000378:metabolism*; D059828:Plant Cells / Q000378:metabolism; D010935:Plant Diseases / Q000276:immunology; D018521:Plant Physiological Phenomena; D010957:Plasmids / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics; D014774:Virulence
chemical_list: D011506:Proteins; D010450:Endopeptidases; D010447:Peptide Hydrolases