The pathovar concept misrepresents the reality of disease as a multifactor process; It’s time to modernize
2023
Morris, Cindy E. | Berge, Odile | Unité de Pathologie Végétale (PV) ; Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | SFP | ISPP
International audience
Show more [+] Less [-]English. The pathovar concept intends to define groups of closely related strains with like pathogenic potential - in terms of the susceptible plant species and the type of symptoms. In turn, pathovar identity is supposed to be useful for diagnostics and disease management. We argue that the pathovar concept cannot meet its intended goals for two fundamental reasons. Firstly, expression of symptoms is the outcome of a process that involves a multitude of factors as represented in the disease triangle. Some of these factors have stochastic or chaotic behaviors. Hence, the outcome of the interaction of a bacterial strain with a plant is conditional and not absolute. This leads to the second obstacle: defining standard criteria by which pathovar identify is attributed objectively. These criteria should specify if pathovar is defined according to natural disease outbreaks or host range tests under controlled conditions. The former ignores differences in opportunity for infection and impedes anticipation of new disease emergences, especially by strains from environmental sources. The latter is faced with unlimited options for host species, cultivars, plant age and physiology and environmental conditions. Furthermore, for numerous plant pathogens, extensive host range tests do not reveal distinct pathovars. We propose that disease potential be estimated by situating bacterial genotypes in a map of risk likelihoods that account for all relevant factors contributing to disease outbreaks.
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