title: Clavibacter michiganensis subsp. michiganensis Vatr1 and Vatr2 transcriptional regulators are required for virulence in tomato.
abstract: The plant pathogen Clavibacter michiganensis subsp. michiganensis is a gram-positive bacterium responsible for wilt and canker disease of tomato. Although disease development is well characterized and diagnosed, molecular mechanisms of C. michiganensis subsp. michiganensis virulence are poorly understood. Here, we identified and characterized two C. michiganensis subsp. michiganensis transcriptional regulators, Vatr1 and Vatr2, that are involved in pathogenicity of C. michiganensis subsp. michiganensis. Vatr1 and Vatr2 belong to TetR and MocR families of transcriptional regulators, respectively. Mutations in their corresponding genes caused attenuated virulence, with the Δvatr2 mutant showing a more dramatic effect than Δvatr1. Although both mutants grew well in vitro and reached a high titer in planta, they caused reduced wilting and canker development in infected plants compared with the wild-type bacterium. They also led to a reduced expression of the ethylene-synthesizing tomato enzyme ACC-oxidase compared with wild-type C. michiganensis subsp. michiganensis and to reduced ethylene production in the plant. Transcriptomic analysis of wild-type C. michiganensis subsp. michiganensis and the two mutants under infection-mimicking conditions revealed that Vatr1 and Vatr2 regulate expression of virulence factors, membrane and secreted proteins, and signal-transducing proteins. A 70% overlap between the sets of genes positively regulated by Vatr1 and Vatr2 suggests that these transcriptional regulators are on the same molecular pathway responsible for C. michiganensis subsp. michiganensis virulence.
authors.forename: Alon
authors.initials: A
authors.lastname: Savidor
authors.forename: Laura
authors.initials: L
authors.lastname: Chalupowicz
authors.forename: Doron
authors.initials: D
authors.lastname: Teper
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Gartemann
authors.forename: Rudolf
authors.initials: R
authors.lastname: Eichenlaub
authors.forename: Shulamit
authors.initials: S
authors.lastname: Manulis-Sasson
authors.forename: Isaac
authors.initials: I
authors.lastname: Barash
authors.forename: Guido
authors.initials: G
authors.lastname: Sessa
mesh_terms: D000192:Actinomycetales / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D000594:Amino Acid Oxidoreductases / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism; D020869:Gene Expression Profiling; D015723:Gene Library; D018551:Solanum lycopersicum / Q000382:microbiology*; D008954:Models, Biological; D010935:Plant Diseases / Q000382:microbiology*; D010937:Plant Growth Regulators / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D017423:Sequence Analysis, RNA; D017384:Sequence Deletion; D015398:Signal Transduction; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D005030:Ethylenes; D010937:Plant Growth Regulators; D010940:Plant Proteins; D014157:Transcription Factors; D037521:Virulence Factors; C036216:ethylene; D000594:Amino Acid Oxidoreductases; C059460:1-aminocyclopropane-1-carboxylic acid oxidase