Submitted to: European Journal of Plant Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/19/2007
Publication Date: 9/10/2007
Citation: White, D., Chen, W. 2007. Towards identifying pathogenic determinants of the chickpea pathogen Ascochyta rabiei.. European Journal of Plant Pathology. Interpretive Summary: Ascochyta blight is a serious disease of chickpea in the United States. Despite intensive studies of this pathosystem, the pathogenic mechanism of A. rabiei is not well understood. This study was initiated to identify and determine the pathogenic determinants of the pathogen. Three significant advances have been made. These advances provide foundation and necessary tools for experimentation of ectopic complementation assays and targeted mutagenesis to elucidate the genetic mechanisms of pathogenicity of A. rabiei.
Technical Abstract: Ascochyta blight is a serious disease of cool season grain legumes (chickpea, faba bean, lentil and pea) caused by fungal species of the anamorphic genus Ascochyta and related genera in the case of pea Ascochyta blight complex. Despite extensive studies on the biology, ecology, epidemiology and management of the disease, little is known about the pathogenic determinants of these pathogens. This research aims at using Ascochyta rabiei as a model for the genus Ascochyta in investigating genetic factors of pathogenicity, with the ultimate goal of elucidating pathogenic mechanisms. Three advances were made: 1) Insertional mutants with altered pathogenicity were identified through in vivo screening, and genomic regions adjacent to the insertion sites in selected mutants were determined; 2) A phage library of A. rabiei genomic DNA was constructed, and the library was estimated to provide complete coverage of the A. rabiei genome. This library was used successfully to recover clones with DNA adjacent to insertional mutation sites and to isolate specific genes; 3) DNA probes specific for an acyl-CoA ligase (cps1) and a polyketide synthase gene (pks1) were developed and library clones containing the corresponding genomic regions were identified from the phage library. These advances provide foundation and necessary tools for experimentation of ectopic complementation assays and targeted mutagenesis to elucidate the genetic mechanisms of pathogenicity of A. rabiei.