Steve St. Martin
Some plant disease resistance genes (major resistance genes) confer high levels of resistance against particular pathogens, and have been well studied over the past decade. Major resistance genes, however, are generally effective only against specific strains of a pathogen, and so become ineffective in the field when new pathogen strains appear. In contrast, partial or quantitative resistance is effective against all strains of a pathogen, albeit providing a lower level of protection. Partial resistance is conferred by multiple genes each with minor contributions, making it difficult to study these genes. As a result, less is known about how these genes operate.
This project is focused on the mechanisms of quantitative resistance of soybean against the oomycete pathogen Phytophthora sojae, which is one of the most damaging soybean diseases. Oomycetes are fungus-like organisms that are actually most closely related to brown algae such as kelp and diatoms. Phytophthora pathogens attack thousands of plant species, including many important crops.
Two approaches will be combined to identify and characterize quantitative resistance genes. Firstly, genetic crosses between soybean cultivars differing in their quantitative resistance to Phytophthora will be analyzed to identify genetic loci (called quantitative trait loci) in soybean that contribute to resistance. Secondly, to determine the mechanisms of resistance contributed by different quantitative resistance loci, the expression levels of thousands of soybean and Phytophthora genes during infection will be assayed using hybridization microarrays. By analyzing pathogen gene expression patterns, the impact of plant defense mechanisms on the pathogen can be assessed. This research will result in new insights into plant defense mechanisms, new genetic and genomic resources for soybean researchers and breeders and new statistical tools for analyzing gene expression data.
Detailed protocols for 8 cultivar and 4 parents experiments are available here
Experimental data for 8 cultivar and 4 parents experiments are available at NCBI (please click on the resources link)