Contributions of Population Genetics to Plant Disease Epidemiology and Management

Abstract

This chapter discusses contributions of population genetics to plant disease epidemiology and management. Population genetics and genetic variation in plant pathogens are subjects that have generated much interest since the late 1980s. Almost every recent issue of major plant pathological and mycological journals has at least one article on genetic variation of a plant pathogen species. Whether population genetics becomes an integral discipline within plant pathology depends, in part, on whether it can be integrated with epidemiology and disease management. Evolutionary biology and population genetics have the potential to deliver much basic information about plant pathogens. Population genetics is a field concerned with determining the extent and pattern of genetic variation in populations with the goal of understanding the evolutionary processes affecting the origin and maintenance of genetic variation. The conceptual framework is based on evolutionary biology and on the processes affecting the genetic composition of populations: selection, mutation, gene flow, genetic drift, and mating systems. The advances in technology also brought about a marked change in emphasis in population genetics of plant pathogens. The biology of pathogens at the population level and processes other than selection has been emphasized. Accurate population definition is essential so that sampling is done in a manner which will enable inferences to be made about the population of interest. From an operational perspective, recognition of population structure is very important when estimating population genetic parameters.