Functional groups of plant pathogens in agroecosystems: a review

Abstract

The concept of functional groups (set of species having similar physiological, ecological or life-history traits) has been largely used for plants, microorganisms, nematodes or insects in agroecosystems. However, this concept has been rarely applied to describe assemblages of plant pathogens. Yet, classification systems in plant pathology resemble this functional approach, as they address different disease processes or life history traits. In this review, we discuss advantages and drawbacks of current classification systems in relation to their application to the ecological management of crop diseases. Then, we propose to reorganize one of the classical plant-pathogen systems in a dichotomous key of functional groups obtained by combining two life-history traits: dispersal and survival strategies. The six functional groups proposed here are soil inhabitants; soil survivors; debris-seed-borne; air-borne; seed-borne, and vector-borne pathogens. We applied these groups to characterize pathogens of two major crops, wheat and tomato, grown in temperate climate regions. Our contribution intends to provide a comprehensive conceptual framework for the design of crop disease management strategies based on ecological principles, as well as to facilitate the interpretation of the occurrence of epidemics in response to the agricultural practices applied in real-world agroecosystems.