Unravelling and managing fusiform rust disease: a model approach for coevolved forest tree pathosystems

摘要

Fusiform rust disease remains the most destructive disease in pine plantations in the southern United States. Our ongoing research is designed to identify, map, and clone the interacting genes of the host and pathogen. Several resistance (R) genes have been identified and genetically mapped using informative pine families and single-spore isolate inoculations. In addition, we are mapping the first of many expected corresponding avirulence (Avr) genes in the fungal pathogen. The Avr genes condition avirulence/virulence and avirulence is required for an incompatible reaction (i.e., no-gall development) to take place within an inoculated tree that carries resistance at the corresponding R gene. We provide an overview of our methodology for identifying and mapping R and Avr genes, an update of our current progress, and a brief discussion of two approaches for predicting R gene genotypes of uncharacterized parental trees and for estimating the efficacy of specific pine genotypes at various planting locations. This paper emphasizes the critical importance of controlled genetic materials of both the host and pathogen for elucidating the genetic nature of resistance and virulence in coevolved forest pathosystems.