Project description:The gram- positive bacterial pathogen Clavibacter michiganensis subsp. michiganensis (Cmm) causes huge economic losses by infecting tomato plants worldwide. Cmm can be spread by contaminated seeds and transplants, penetrating the plant through natural openings or wounds and is transferred through the plant xylem. While in recent years significant progress has been made to elucidate plant responses to pathogenic gram-negative bacteria by gene expression studies, the molecular mechanisms that lead to disease symptoms caused by gram-positive bacteria like Cmm remain elusive. An indigenous virulent Cmm strain isolated from a farm crop of Pomodoro tomatoes in southern Greece was used for the infection of EKSTASIS F1 hybrid tomato seedlings. Here, we present the results of a deep RNA- sequencing (RNA-seq) analysis performed to characterize the dynamic expression profile of tomato genes upon Cmm infection.
Project description:Clavibacter michiganensis subsp. michiganensis is an important Gram-positive phytopathogenic bacteria that causes bacterial wilt and canker in tomato. The genome of the type strain, NCPPB382, has been sequenced and annotated, however comparative genomics suggests that certain regions are under- or misannotated. In order to improve the genome annotation, we have undertaken a proteogenomic study of this important pathogen. Samples were grown in culture and the proteome of the pellet and supernatant were analyzed separately using shotgun HPLC-MS/MS. These proteomics datasets were analyzed and a number of missing gene were found and a number of existing gene calls were modified.
Project description:We report here the complete genome sequence of Clavibacter michiganensis subsp. insidiosus R1-1, isolated in Minnesota, USA. The R1-1 genome, generated by a de novo assembly of PacBio sequencing data, is the first complete genome sequence available for this subspecies.
Project description:Clavibacter michiganensis subsp. michiganensis (Cmm) is a Gram-positive seed-transmitted bacterial phytopathogen responsible for substantial economic losses by adversely affecting tomato production worldwide. A high-throughput, cell-based screen was adapted to identify novel small molecule growth inhibitors to serve as leads for future bactericide development. A library of 4,182 compounds known to be bioactive against Saccharomyces cerevisiae was selected for primary screening against Cmm wild-type strain C290 for whole-cell growth inhibition. Four hundred sixty-eight molecules (11.2% hit rate) were identified as bacteriocidal or bacteriostatic against Cmm at 200 ?M. Seventy-seven candidates were selected based on Golden Triangle analyses for secondary screening. Secondary screens showed that several of these candidates were strain-selective. Several compounds were inhibitory to multiple Cmm strains as well as Bacillus subtilis, but not to Pseudomonas fluorescens, Mitsuaria sp., Lysobacter enzymogenes, Lactobacillus rhamnosus, Bifidobacterium animalis, or Escherichia coli. Most of the compounds were not phytotoxic and did not show overt host toxicity. Using a novel 96-well bioluminescent Cmm seedling infection assay, we assessed effects of selected compounds on pathogen infection. The 12 most potent novel molecules were identified by compiling the scores from all secondary screens combined with the reduction of pathogen infection in planta. When tested for ability to develop resistance to the top-12 compounds, no resistant Cmm were recovered, suggesting that the discovered compounds are unlikely to induce resistance. In conclusion, here we report top-12 compounds that provide chemical scaffolds for future Cmm-specific bactericide development.