Plant diseases are among the greatest deterrents to crop production worldwide. Hence, major efforts have been devoted to understanding the mechanisms of genetic resistance and incorporating them into breeding programs to offset yield loss caused by pathogens. This project will focus on the well-characterized, barley-powdery mildew pathosystem to address fundamental questions in host-plant resistance. In this model system, resistance to the obligate fungal pathogen, Blumeria graminis f. sp. hordei, is controlled by the specific combinations of barley resistance genes, designated Ml, and corresponding powdery mildew avirulence genes, designated AvrMl.
The overall objective of this proposal is to utilize functional genomics tools and resources available to barley, rice, and the model dicot Arabidopsis thaliana, to accelerate comparative analysis of disease defense pathways important in agriculture. The team will exploit the detailed molecular genetics of Mla-specified, barley-powdery mildew interactions as a launching point to investigate defense gene function across wide taxonomic boundaries. In years 1 & 2, the team will take advantage of the publicly available Barley1 GeneChip, a uniform RNA profiling platform that allows the investigation of 22,000 cereal genes in a single experiment. Near-isogenic barley lines that possess various Mla resistance alleles and associated mutants will be utilized to identify significant new genes in disease resistance networks. Project data will be integrated into BarleyBase (http://barleybase.org/) to facilitate the bioinformatic and statistical analysis of co-regulated genes. In years 2 to 4, high-throughput reverse genetic systems in barley and Arabidopsis will be used to functionally validate candidate genes in resistance pathways of both monocot and dicot plants. Phenotypic data from these studies will establish the contributions of individual genes to overall resistance responses.
Broader impacts of the proposed project will be accomplished via active participation in the "Molecular Biotechnology and Genomics" NSF-REU Center, the Program for Women in Science and Engineering, and the NSF-NIH-BBSI summer institute in Bioinformatics at Iowa State University, where science-bound undergraduates who do not have the opportunity to participate in research at their home institutions will be involved. Outreach to secondary school students will be undertaken by hosting grade 7-12 biology teachers in participating laboratories for summer internships through the NSF-RET program (www.plantgenomeoutreach.eeob.iastate.edu/). This multi-disciplinary team will provide advanced training opportunities for graduate students and postdoctoral researchers that integrate genomics, plant-pathogen interactions, statistics, and bioinformatics. This will be enhanced by worldwide public access to all project data through the on-line relational database for cereal microarrays, BarleyBase, as well as ArrayExpress, and NCBI-GEO. Thus, these activities will promote research, education, and dissemination of our results to a broad audience, while developing a new generation of agricultural scientists.
