Submitted to: Journal of Microbiology and Biotechnology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/17/2012
Publication Date: 4/2/2012
Citation: Kim, S.D., De La Fuente, L., Weller, D.M., Thomashow, L.S. 2012. Colonizing ability of Pseudomonas fluorescens 2112, among collections of 2,4-diacetylphloroglucinol-producing Pseudomonas fluorescens spp. in pea rhizosphere.. Journal of Microbiology and Biotechnology. 22(6):763-770. Interpretive Summary: The ability of plant-beneficial strains of bacteria to colonize roots is an essential first step in the processes leading to successful plant growth promotion and biological control of plant pathogens. Once established, biocontrol agents must also antagonize pathogens by one or more mechanisms that include antibiosis, competition, and stimulation of the plant’s own defense mechanisms. In this study the beneficial Korean bacterial strain 2112, which produces the natural antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) was shown to colonize the roots of pea as well as the model strains Q8r1-96 and MVP1-4, both of which were shown previously to be highly efficient root colonizers of pea. Strains that produce 2,4-DAPG have been classified into over 20 genotypes that are useful in predicting the ability of a strain to colonize a particular host plant. This study is the first to show that strains belonging to the C genotype are as competitive as strains of the D and P genotypes on pea.
Technical Abstract: Pseudomonas fluorescens 2112, isolated in Korea as an indigenous antagonistic bacteria, can produce 2,4-diacetylphloroglucinol (2,4-DAPG) and the siderophore pyoveridin2112 for the control of Phytophthora blight of red-pepper. P. fluorescens 2112 was classified into a new genotype C among the 17 genotypes of 2,4-DAPG producers, by phlD restriction fragment length polymorphism (RFLP). The colonizing ability of P. fluorescens 2112 in pea rhizosphere was equal to the well-known pea colonizers, P. fluorescens Q8r1 (genotype D) and MVP1-4 (genotype P), after 6 cycling cultivations for 18 weeks. Four tested 2,4- DAPG-producing Pseudomonas spp. could colonize with about a 96% dominance ratio against total bacteria in pea rhizosphere. The strain P. fluorescens 2112 was as good a colonizer as other Pseudomonas spp. genotypes in pea plant growth-promoting rhizobacteria.