title: Differential ability of genotypes of 2,4-diacetylphloroglucinol-producing Pseudomonas fluorescens strains to colonize the roots of pea plants.
abstract: Indigenous populations of 2,4-diacetylphloroglucinol (2,4-DAPG)-producing fluorescent Pseudomonas spp. that occur naturally in suppressive soils are an enormous resource for improving biological control of plant diseases. Over 300 isolates of 2,4-DAPG-producing fluorescent Pseudomonas spp. were isolated from the rhizosphere of pea plants grown in soils that had undergone pea or wheat monoculture and were suppressive to Fusarium wilt or take-all, respectively. Representatives of seven genotypes, A, D, E, L, O, P, and Q, were isolated from both soils and identified by whole-cell repetitive sequence-based PCR (rep-PCR) with the BOXA1R primer, increasing by three (O, P, and Q) the number of genotypes identified previously among a worldwide collection of 2,4-DAPG producers. Fourteen isolates representing eight different genotypes were tested for their ability to colonize the rhizosphere of pea plants. Population densities of strains belonging to genotypes D and P were significantly greater than the densities of other genotypes and remained above log 6.0 CFU (g of root)(-1) over the entire 15-week experiment. Genetic profiles generated by rep-PCR or restriction fragment length polymorphism analysis of the 2,4-DAPG biosynthetic gene phlD were predictive of the rhizosphere competence of the introduced 2,4-DAPG-producing strains.
authors.affiliation: Root Disease and Biological Control Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Pullman, WA 99164-6430, USA.
authors.forename: Blanca B
authors.initials: BB
authors.lastname: Landa
authors.forename: Olga V
authors.initials: OV
authors.lastname: Mavrodi
authors.forename: Jos M
authors.initials: JM
authors.lastname: Raaijmakers
authors.forename: Brian B
authors.initials: BB
authors.lastname: McSpadden Gardener
authors.forename: Linda S
authors.initials: LS
authors.lastname: Thomashow
authors.forename: David M
authors.initials: DM
authors.lastname: Weller
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D005453:Fluorescence; D005787:Gene Frequency; D005838:Genotype; D018532:Pisum sativum / Q000382:microbiology*; D010696:Phloroglucinol / Q000031:analogs & derivatives / Q000378:metabolism*; D018517:Plant Roots / Q000382:microbiology*; D011551:Pseudomonas fluorescens / Q000378:metabolism* / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; C096183:PhlD protein, Pseudomonas; C059817:2,4-diacetylphloroglucinol; D010696:Phloroglucinol