title: CITRX thioredoxin interacts with the tomato Cf-9 resistance protein and negatively regulates defence.
abstract: To identify proteins involved in tomato Cf-9 resistance protein function, a yeast two-hybrid screen was undertaken using the cytoplasmic C-terminus of Cf-9 as bait. A thioredoxin-homologous clone, interacting specifically with Cf-9, was identified and called CITRX (Cf-9-interacting thioredoxin). Virus-induced gene silencing (VIGS) of CITRX resulted in an accelerated Cf-9/Avr9-triggered hypersensitive response in both tomato and Nicotiana benthamiana, accompanied by enhanced accumulation of reactive oxygen species, alteration of protein kinase activity and induction of defence-related genes. VIGS of CITRX also conferred increased resistance to the fungal pathogen Cladosporium fulvum in the otherwise susceptible Cf0 tomato. CITRX acts as a negative regulator of the cell death and defence responses induced through Cf-9, but not Cf-2. Recognition of the Cf-9 C-terminus by CITRX is necessary and sufficient for this negative regulation. This is the first study that implicates thioredoxin activity in the regulation of plant disease resistance.
authors.affiliation: The Sainsbury Laboratory, John Innes Centre, Norwich Research Park, Norwich, UK.
authors.forename: Susana
authors.initials: S
authors.lastname: Rivas
authors.forename: Alejandra
authors.initials: A
authors.lastname: Rougon-Cardoso
authors.forename: Matthew
authors.initials: M
authors.lastname: Smoker
authors.forename: Leif
authors.initials: L
authors.lastname: Schauser
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Yoshioka
authors.forename: Jonathan D G
authors.initials: JD
authors.lastname: Jones
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004789:Enzyme Activation; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D006861:Hydrogen Peroxide / Q000378:metabolism; D007113:Immunity, Innate / Q000235:genetics / Q000502:physiology*; D018551:Solanum lycopersicum / Q000737:chemistry* / Q000235:genetics; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D016877:Oxidants / Q000378:metabolism; D010802:Phylogeny; D018515:Plant Leaves / Q000033:anatomy & histology / Q000378:metabolism; D010940:Plant Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D010942:Plant Viruses / Q000235:genetics / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013879:Thioredoxins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: C109609:Cf protein, Lycopersicon esculentum; D008562:Membrane Glycoproteins; D016877:Oxidants; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D013879:Thioredoxins; D006861:Hydrogen Peroxide; D011494:Protein Kinases