ECOLOGICAL AND GENETIC DIVERSITY OF SOILBORNE PATHOGENS AND INDIGENOUS MICROFLORA

Soilborne diseases caused by plant pathogenic organisms result in major economic losses to agricultural production. These diseases pose a challenge to agriculture since they are difficult to control, as chemical control is usually ineffective and many soilborne pathogens produce resting structures that survive in the soil for a long time, resulting in soils unsuitable for production. Additionally, the emergence of plant pathogenicity in fungal populations is an intriguing matter for which we still do not have a clear understanding, and yet this may hold important clues to designing novel and more efficient practices to manage plant diseases. Plant pathogenic fungi often have complex ecological interactions with the niche being occupied, such as soil and plants. However, these interaction have been largely ignored by plant pathologists when not accompanied by disease. This is specially the case for two fungal species, Fusarium oxysporum and Verticillium dahliae. These fungi cause vascular wilts to hundreds of crop plants, but also have a complex endophytic biology. Sustainable production systems must integrate disease management practices that incorporate disease resistance, nutrient enhancement, and biocontrol, among others, and must target a population of the pathogen and not a single individual. Pathogen populations may be very diverse, in particular regarding their virulence. Therefore, it is of key importance to understand the interactions between host genotypes, biocontrol agents and pathogen populations, within an ecological framework that includes resident and augmented microbial communities, and to incorporate this information into disease management systems.