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Alternaria brassicicola is a successful saprophyte and necrotrophic plant pathogen. Several A. brassicicola genes have been characterized as affecting pathogenesis of Brassica species. To study regulatory mechanisms of pathogenesis, we mined 421 genes in silico encoding putative transcription factors in a machine-annotated, draft genome sequence of A. brassicicola. In this study, targeted gene disruption mutants for 117 of the transcription factor genes were produced and screened. Three of these genes were associated with pathogenesis. Disruption mutants of one gene (AbPacC) were nonpathogenic and another gene (AbVf8) caused lesions less than half the diameter of wild-type lesions. Unexpectedly, mutants of the third gene, Amr1, caused lesions with a two-fold larger diameter than the wild type and complementation mutants. Amr1 is a homolog of Cmr1, a transcription factor that regulates melanin biosynthesis in several fungi. We created gene deletion mutants of Δamr1 and characterized their phenotypes. The Δamr1 mutants used pectin as a carbon source more efficiently than the wild type, were melanin-deficient, and more sensitive to UV light and glucanase digestion. The AMR1 protein was localized in the nuclei of hyphae and in highly melanized conidia during the late stage of plant pathogenesis. RNA-seq analysis revealed that three genes in the melanin biosynthesis pathway, along with the deleted Amr1 gene, were expressed at low levels in the mutants. In contrast, many hydrolytic enzyme-coding genes were expressed at higher levels in the mutants than in the wild type during pathogenesis. The results of this study suggested that a gene important for survival in nature negatively affected virulence, probably by a less efficient use of plant cell-wall materials. We speculate that the functions of the Amr1 gene are important to the success of A. brassicicola as a competitive saprophyte and plant parasite.
Pubmed ID: 23133370
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his table shows the metadata and links to sources of the data and citations associated with the publicly available metagenome sequences used in the Dinsdale, Edwards, et al., analysis of 87 different metagenomes. The links will take you to the annotated sequences in the metagenomics SEED, CAMERA, and the NCBI Short Read Archve. Please note that all metagenomes are currently available to download via the ftp links, some are available in the meta-RAST, and other links will be added as soon as they become available. Citations for individual metagenomes will also be added as and when they become available. DNA sequences for all metagenomes are avaialble via anonymous FTP. Sponsor. This project was supported by the Gordon and Betty Moore Foundation Marine Microbial Initiative, National Science Foundation grants (F.R. and D.L.V.), a Department of Commerce ATP grant (F.R.), a National Research Initiative Competitive Grant from the USDA Cooperative State Research, Education and Extension Service (B.W.), the National Institute of Allergy and Infectious Diseases, the National Institutes of Health and the Department of Health and Human Services (R.S.).
View all literature mentionsSoftware ultrafast memory efficient tool for aligning sequencing reads. Bowtie is short read aligner.
View all literature mentionsSoftware platform to explore, analyze and visualize data. SAS 9.4 is part of SAS Platform. Standardized data governance and management from statistical software company SAS.
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