Identification of pathogen avirulencegenes in the fusiform rust pathosystem

Abstract

The Cronartium quercuum f.sp. fusiforme (Cqf) whole genome sequencing project will enable identification of avirulence genes in the most devastating pine fungal pathogen in the southeastern United States. Amerson and colleagues (unpublished) have mapped nine fusiform rust resistance genes in loblolly pine, suggesting that at least nine corresponding avirulence genes likely exist in the fungus. Identification of these avirulence genes would greatly facilitate selection of resistant pine genotypes for deployment to forest plantations. Based on work in other rusts, we anticipate avirulence genes may encode secreted effector proteins that interact directly or indirectly with host resistance proteins. As a step toward testing this hypothesis, we genetically mapped the Cqf avirulence gene Avr1, which specifically interacts with the Fr1 resistance gene, with the goal of integrating this map with the Cqf genome sequence assembly so that Avr1 can be identified. Once Avr1 is identified, we want to determine its allele frequency across geographically defined hazard maps for fusiform rust, to help guide genotype deployment by growers. We view identification of Avr1 as our initial case study, guiding our strategy to efficiently identify additional avirulence genes in Cqf that in turn can be used to guide plantation deployment of all genotypes currently represented in southern pine breeding programs.

Parent Publication

• Proceedings of the fourth international workshop on the genetics of host-parasite interactions in forestry: Disease and insect resistance in forest trees

Citation

Davis, John M.; Smith, Katherine E.; Pendleton, Amanda; Smith, Jason A.; Nelson, C. Dana. 2012. Identification of pathogen avirulencegenes in the fusiform rust pathosystem. In: Sniezko, Richard A.; Yanchuk, Alvin D.; Kliejunas, John T.; Palmieri, Katharine M.; Alexander, Janice M.; Frankel, Susan J., tech. coords. Proceedings of the fourth international workshop on the genetics of host-parasite interactions in forestry: Disease and insect resistance in forest trees. Gen. Tech. Rep. PSW-GTR-240. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture. p. 215.