Dr. Linda S. Thomashow

Linda S. Thomashow

509-335-0930
linda.thomashow@ARS.USDA.GOV

USDA-ARS Research Geneticist and adjunct to the Molecular Plant Sciences and the Departments of Microbiology and Plant Pathology. Ph.D. 1979, UCLA.

Research

Certain beneficial strains of fluorescent Pseudomonas bacterial species colonize the roots of plants and provide biological control of soilborne plant pathogens through the production in situ of small organic molecules with antibiotic activity. One focus of our research is to understand the genetics, biochemistry, and regulation of synthesis of two classes of these metabolites, phenazine and phloroglucinol compounds, with the goal of improving the level and consistency of performance of the biocontrol agents that produce them. Because these bacteria must deliver the antibiotics to sites on roots impacted by fungal pathogens, we also are working to understand the genetic and physiological basis for a particularly aggressive root colonization phenotype exhibited by some of our strains. Finally, because we have engineered multiple antibiotic biosynthesis pathways and biocontrol mechanisms into some of our most aggressive root colonizers, we are studying the effects of these bacteria on their plant hosts and other, nontarget plant-associated microorganisms.

Selected Publications

Mavrodi, D. V., Blankenfeldt, W., and Thomashow, L. S. 2006. Phenazine compounds in fluorescent Pseudomonas spp: Biosynthesis and regulation. Annu. Rev. Phytopathol. (in press).

Khan, S. R., Mavrodi D. V., Jog, G. J., Suga, H., Thomashow, L. S., and Farrand, S. K. 2005. Activation of the phz operon of Pseudomonas fluorescens 2-79 requires the LuxR homolog PhzR, N-(3-OH-hexanoyl)-L-homoserine lactone produced by the LuxI homologue PhzI, and a cis-acting phz-box. J. Bacteriol. 187: 6517-6527.

Validov, S., Mavrodi, O., De La Fuente, L., Boronin, A., Weller, D., Thomashow, L., and Mavrodi, D. 2005. Antagonistic activity among 2,4-diacetylphloroglucinol-producing fluorescent Pseudomonas spp. FEMS Microbiol. Lett. 242:249-256.

Paulsen, I.T., Press, C., Ravel, J., Kobayashi, D. Y., Myers, G. S. A., Mavrodi, D. V., DeBoy, R.T., Seshadri, R., Ren, Q., Madupu, R., Dodson, R. J., Durkin, A. S., Brinkac, L. M., Daugherty, S. C., Sullivan, S. A., Rosovitz, M. J., Gwinn, M. L., Zhou, L., Nelson, W. C., Weidman, J., Watkins, K., Tran, K., Khouri, H., Pierson, E. A., Pierson, L. S., Thomashow, L. S., and Loper, J. E. 2005. Complete genome sequence of the plant commensal Pseudomonas fluorescens Pf-5: insights into the biological control of plant disease. Nature Biotechnology 23: 873-878.

Blankenfeldt, W., Kuzin, A. P., Skarina, T., Korniyenko, Y., Tong, L., Bayer, P., Janning, P., Thomashow, L. S., and Mavrodi, D. V. 2004. Structure and function of phenazine biosynthesis protein PhzF from Pseudomonas fluorescens 2-79. Proc. Natl. Acad. Sci. U.S.A. 101:16431-16436.

Mavrodi, D. V., Bleimling, N., Thomashow, L. S., and Blankenfeldt, W. 2004. The purification, crystallization and preliminary structural characterization of PhzF, a key enzyme in the phenazine-biosyntheis pathway from Pseudomonas fluorescens 2-79. Acta Crystallogr. D 60:184-186.

Huang, Z., Bonsall, R. F., Mavrodi, D. V., Weller, D. M., and Thomashow, L. S. 2004. Transformation of Pseudomonas fluorescens with genes for biosynthesis of phenazine-1-carboxylic acid improves biocontrol of Rhizoctonia root rot and in situ antibiotic production. FEMS Microbiol. Ecol. 49:243-251.

De La Fuente, L., Thomashow, L. S., Weller, D. M., Bajsa, N., Quagliotto, L., Chernin L., and Arias, A. 2004. Pseudomonas fluorescens UP61 isolated from birdsfoot trefoil rhizosphere produces multiple antibiotics and exerts a broad spectrum of biocontrol activity. Eur. J. Plant Pathol. 110:671-681.

Ahuja, E. G., Mavrodi, D. V, Thomashow, L. S., and Blankenfeldt, W. 2004. Overexpression, purification and crystallization of PhzA, the first enzyme of the phenazine biosynthesis pathway of Pseudomonas fluorescens 2-79. Acta Crystallogr. D 60:1129-1131.

Viebahn, M., Glandorf, D. C. M., Ouwens, T. W. M., Smit, E., Leeflang, P., Wernars, K. Thomashow, L. S., van Loon, L. C., and Bakker, P. A. H. M. 2003. Repeated introduction of genetically modified Pseudomonas putida WCS358r without intensified effects on the indigenous microflora of field-grown wheat. Appl. Environ. Microbiol. 69:3110-3118.

Mavrodi, D. V., N. Bleimling, L. S. Thomashow, and W. Blankenfeldt. 2003. The purification, crystallization and preliminary structural characterization of PhzF, a key enzyme in the phenazine-biosynthetic pathway from Pseudomonas fluorescens 2-79. Acta Cryst. D:60:184-186.

Denison, R. F., D. Bledsoe, M. Kahn, F. O’Gara, E. L. Simms, and L. S. Thomashow. 2003. Cooperation in the rhizosphere and the “free rider” problem. Ecology. 84:838-845.

Landa, B.B., D. M. Mavrodi, L. S. Thomashow, and D. M. Weller. 2003. Interactions between strains of 2,4-diacetylphloroglucinol-producing Pseudomonas fluorescens in the rhizosphere of wheat. Phytopathology. 93:982-994.

Raaijmakers, J. M., Weller, D. M., Thomashow, L. S., and Cook, R. J. 2002. Biocontrol of take-all. United States Patent No. 6,447,770 B1.

Weller, D. M., J. M. Raaijmakers, B. B. McSpadden Gardener, and L. S. Thomashow. 2002. Microbial populations responsible for specific soil suppressiveness to plant pathogens. Annu. Rev. Phytopathol. 40:309-348.

Landa, B. B., Mavrodi, O. V., Raaijmakers, J. M., McSpadden Gardener, B. B., Thomashow, L. S., and Weller, D. M. 2002. Differential ability of genotypes of 2,4-diacetylphloroglucinol-producing Pseudo-monas fluorescens strains to colonize the roots of pea plants. Appl. Environ. Microbiol. 68:3226-3237.

Bakker, P.A.H.M., D.C.M. Glandorf, M. Viebahn, T.W.M. Ouwens, E. Smit, P. Leeflang, K. Wernars, L.S. Thomashow, J.E. Thomas-Oates, and L C. van Loon. 2002. Effects of Pseudomonas putida modified to product phenazine-1-carboxylid acid and 2,4-diacetyl-phloroglucinol on the microflora of field grown wheat. Antonie van Leeuwenhoek 81:617-624.

Mavrodi, D. V., O. V. Mavrodi, B. B. McSpadden-Gardener, B. B. Landa, D. M. Weller, and L. S. Thomashow. 2002. Identification of differences in genome content among phlD-positive Pseudomonas fluorescens strains by using PCR-based subtractive hybridization. Appl. Environ. Microbiol. 68:5170-5176.

Thomashow, L. S., Bonsall, R. F., and Weller, D. M. 2002. Antibiotic production by soil and rhizosphere microbes in situ. Pages 636-647 in: Manual of Environmental Microbiology, 2nd Edition. C. J. Hurst, R. L. Crawford, G. R. Knudsen, M. J. McInerney, and L. D. Stetzenbach, eds. ASM Press, Washington, D.C. 1138 pp.

Weller, D.M., Raaijmakers, J.M., McSpadden, Gardener, B.B. and Thomashow, L.S. 2002. Microbial populations responsible for specific soil suppressiveness to plant pathogens. Annu. Rev. Phytopathol. 40:309-348.

Mavrodi, D.V., Bonsall, R.F., Delaney, S.M., Soule, M.J., Phillips, G. and Thomashow, L.S. 2001. Functional analysis of genes for biosynthesis of pyocyanin and phenazine-1-carboxamide from Pseudomonas aeruginosa PAO1. J Bacteriol. 183:6454-6465.

McDonald, M., Mavrodi, D.V., Thomashow, L.S. and Floss, H.G. 2001. Phenazine biosynthesis in Pseudomonas fluorescens: Branchpoint from the primary shikimate biosynthetic pathway and role of phenazine-1,6-dicarboxylic acid. J. Am. Chem. Soc. 123:9459-9460.

Glandorf, D.C.M., Verheggen, P., Jansen, T., Jorritsma, J. W., Smit, E., Leeflang, P., Wernars, K., Thomashow, L.S., Laureijs, E., Thomas-Oates, J.E., Bakker, P.A.H.M. and van Loon, L.C. 2001. Effect of genetically modified Pseudomonas putida WCS358r on the fungal rhizosphere microflora of field-grown wheat. Appl. Envir. Microbiol. 67:3371-3378.

Bangera, M.G. and Thomashow, L.S. 1999. Identification and characterization of a gene cluster for synthesis of the polyketide antibiotic 2,4-diacetylphloroglucinol from Pseudomonas fluorescens Q2-87. J. Bacteriol. 181:3155-3163.

Mavrodi, D.V., Mavrodi, O.V., McSpadden-Gardener, B.B., Landa, B.B., Weller, D.M. and Thomashow, L.S. 2002. Identi- fication of differences in genome content among phlD-positive Pseudomonas fluorescens strains by using PCR-based subtractive hybridization. Appl. Environ. Microbiol. 68(10):5170-5176.