Analysis of new type III effectors from Xanthomonas uncovers XopB and XopS as suppressors of plant immunity.
The pathogenicity of the Gram-negative plant-pathogenic bacterium Xanthomonas campestris pv. vesicatoria (Xcv) is dependent on type III effectors (T3Es) that are injected into plant cells by a type III secretion system and interfere with cellular processes to the benefit of the pathogen. In this study, we analyzed eight T3Es from Xcv strain 85-10, six of which were newly identified effectors. Genetic studies and protoplast expression assays revealed that XopB and XopS contribute to disease symptoms and bacterial growth, and suppress pathogen-associated molecular pattern (PAMP)-triggered plant defense gene expression. In addition, XopB inhibits cell death reactions induced by different T3Es, thus suppressing defense responses related to both PAMP-triggered immunity (PTI) and effector-triggered immunity (ETI). XopB localizes to the Golgi apparatus and cytoplasm of the plant cell and interferes with eukaryotic vesicle trafficking. Interestingly, a XopB point mutant derivative was defective in the suppression of ETI-related responses, but still interfered with vesicle trafficking and was only slightly affected with regard to the suppression of defense gene induction. This suggests that XopB-mediated suppression of PTI and ETI is dependent on different mechanisms that can be functionally separated.
Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany.
Sebastian
S
Schulze
Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany.
Sabine
S
Kay
Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany.
Daniela
D
Büttner
Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany.
Monique
M
Egler
Leibniz Institute of Plant Biochemistry, Weinberg 3, D-06120 Halle (Saale), Germany.
Lennart
L
Eschen-Lippold
Biozentrum, Martin-Luther-University Halle-Wittenberg, Weinbergweg 22, D-06120 Halle (Saale), Germany.
Gerd
G
Hause
Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany.
Antje
A
Krüger
Leibniz Institute of Plant Biochemistry, Weinberg 3, D-06120 Halle (Saale), Germany.
Justin
J
Lee
Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany.
Oliver
O
Müller
Leibniz Institute of Plant Biochemistry, Weinberg 3, D-06120 Halle (Saale), Germany.
Dierk
D
Scheel
Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany.
Robert
R
Szczesny
Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany.
Frank
F
Thieme
Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany.
Ulla
U
Bonas
D017360:Arabidopsis / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D058947:Bacterial Secretion Systems / Q000235:genetics*; D016923:Cell Death; D015964:Gene Expression Regulation, Bacterial; D018506:Gene Expression Regulation, Plant; D005798:Genes, Bacterial / Q000235:genetics; D056726:Genetic Association Studies; D006056:Golgi Apparatus / Q000378:metabolism; D059828:Plant Cells / Q000382:microbiology; D057865:Plant Immunity / Q000235:genetics; D010940:Plant Proteins / Q000378:metabolism; D021381:Protein Transport / Q000235:genetics; D019657:Solanaceae / Q000166:cytology / Q000382:microbiology; D014774:Virulence / Q000235:genetics; D016959:Xanthomonas campestris / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity
D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D010940:Plant Proteins