ENRICHMENT AND GENOTYPIC DIVERSITY OF PHLD-CONTAINING FLUORESCENT PSEUDOMONAS SPP. IN TWO SOILS AFTER A CENTURY OF WHEAT AND FLAX MONOCULTURE

Authors: LANDA, B - INST. DE AGRI. SOSTENIBLE; MAVRODI, O. - WASHINGTON STATE UNIV.; SCHROEDER, K.L. - WASHINGTON STATE UNIV.; ALLENDE-MOLAR, R. - WASHINGTON STATE UNIV.; Weller, David

Submitted to: Proceedings of Workshop on Global Int Org Biocontrol (IOBC) Working Group
Publication Type: Proceedings
Publication Acceptance Date: 9/1/2005
Publication Date: N/A
Citation: N/A

Interpretive Summary: Take-all decline (TAD) is a natural biological control of take-all disease of wheat, caused by Gaeumannomyces graminis var. tritici. TAD develops because of the buildup of isolates of Pseudomonas fluorescens, which produce the antifungal compound 2,4-diacetylphloroglucinol (DAPG) during wheat monoculture. DAPG-producing strains also are enriched by monoculture of other crops such as flax and pea, indicating that DAPG producers provide a natural level of plant defense on a broader range of crops than previously thought.

Technical Abstract: Fluorescent Pseudomonas spp. producing the antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) play a key role in take-all decline, which develops when a field is continuously cropped to wheat or barley after a take-all outbreak, and also contribute to the disease suppressiveness of other soils. In this study, we showed that over many years of monoculture, the crop species grown in a field enriches for genotypes of 2,4-DAPG producers from the reservoir of genotypes naturally present in the soil that are especially adapted to colonize the rhizosphere of the crop grown.