Project Number: 5348-21000-024-27
Project Type: Specific Cooperative Agreement

Start Date: Jul 20, 2011
End Date: Jul 31, 2013

Objective:
The primary objective of the project is to investigate the ecology, population biology and pathogenic mechanisms of plant pathogens as they interaction with cool season grain legumes that include pea, chickpea and lentil. The project will focus on pathogens, such as species of Ascochyta, Erysiphe, Sclerotinia, and Stemphylium, with economical significance to US production of cool season grain legumes. The second objective of the project is to develop management practices for controlling or mitigating the adverse effect of pathogens on crop production.

Approach:
1. Strains of the pathogens will be collected from infected cool season grain legume plants from various geographic regions, and isolated in pure culture using mycological techniques. Isolates will be maintained in cellulose filter paper and in 15% glycerol at -80 C. Additional isolates will be obtained from cooperators from other locations under appropriate USDA permits. 2. To study population structure of the grain legume pathogens, total genomic DNA will be isolated from each isolate using standard methods for DNA isolation and quantification. Microsatellite alleles of isolates will be determined using PCR, and haplotypes (multi locus genotype or combination of microsatellite alleles) will be determined for each isolate and used to examine genetic relatedness among isolates. 3. Some secondary metabolites like toxins of fungal pathogens play important roles in causing diseases. To study secondary metabolites of the fungal pathogens, pathogen cultures will be grown in appropriate culture media. Secreted metabolites from the cultures will be isolated and purified using appropriate solvents and will be detected and quantified using high performance liquid chromatography. Unknown compounds will be identified using nuclear magnetic resonance spectroscopy and mass spectrometry. Biological activities of the secondary metabolites will be tested using appropriate bioassays. 4. To increase our mechanistic understanding of pathogenesis of grain legume pathogens, genomic segments related to or responsible for pathogenesis will be identified through generation of non-pathogenic mutants. Random mutagenesis will be used to generate tagged mutations and mutants will be screened for virulence. Mutants with altered virulence will be further characterized in terms of genetic mutations, function of the mutated genes, and patterns of gene expression. 5. To identify resistant sources in grain legumes, germplasm lines and cultivars of pea, chickpea and lentil will be planted in the greenhouse. At appropriate growth stages, the test plants will be inoculated with the target pathogens and incubated for disease development at environmental conditions conducive to disease development. Disease severity of the plant genotypes will be scored with appropriate rating scales and resistance will be rated and evaluated in repeated experiments.