Sunday, February 17, 2013
Room 206 (Hynes Convention Center)
Dr. Thomashow studies the plant-growth-promoting rhizobacterium (PGPR). Pseudomonas fluorescens Q8r1-96 was isolated from a soil naturally suppressive to take-all disease of wheat (take-all decline, TAD). TAD develops during wheat monoculture following a severe outbreak of take-all and results from the buildup of strains of Pseudomonas fluorescens that produce the antifungal metabolite 2,4-diacetylphloroglucinol (DAPG). The unexpected finding that DAPG producers also are enriched in a pea wilt suppressive soil led Thomashow's group to characterize the genotypic and phenotypic relationships among isolates from fields that had experienced extended monoculture of wheat, peas, or flax. These studies resulted in the identification of a new class of "premier" PGPR - strains defined by DNA fingerprinting and exemplified by P. fluorescens Q8r1-96 from TAD soil. Premier PGPR are minimally affected by soil type and environmental conditions, colonize roots consistently, and enhance plant growth when applied at low doses.