Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 5/1/2005
Publication Date: 7/7/2005
Citation: Mazzola, M., Raaijmakers, J.M. 2005. Recruitment of disease suppressive soil microorganisms through crop cultivation. Proceedings IX International Congress of Ecology. P. 417. Interpretive Summary:
Technical Abstract: Plant cultivation is a viable means to actively manipulate the composition and function of resident soil microbial communities. Several accounts exist concerning the induction of disease suppressive soils realized as a result of continuous crop monoculture. One such example is the spontaneous decline in the incidence of take-all of wheat, a disease incited by the fungal pathogen Gauemannomyces graminis var. tritici, observed after one or two severe outbreaks of the disease in wheat monoculture production systems. A series of studies demonstrated that development of take-all decline is elicited, in part, via plant selection and enrichment of 2,4-diacetylphloroglucinol-producing fluorescent Pseudomonas spp. resident to soil ecosystems. In native soils, a state of take-all decline characteristically developed when 2,4-DAPG producing pseudomonads attained populations of approximately 10**5 cfu g**-1 root. A similar level of disease suppression also was documented when an individual 2,4-DAPG strain was etablished at this population in a sterile soil system. The capacity to recruit functional populations of 2,4-DAPG-producers from the same resident bacterial community was wheat genotype-dependent. The dominant 2,4-DAPG producing genotype selected from resident populations was both soil and wheat-genotype dependent. This selection factor could be of significace to the development of take-all decline as certain genotypes are superior rhizosphere colonists and thus provide a superior level of disease control. These data provide further evidence for the genotype-dependent capacity of plans to select for specific functional microbial communities. We postulate that selection of the appropriate plant genotype could substantially enhance recruitment of 2,4-DAPG producers from native soil populations and reduce the time period required for establishment of disease decline.