1887

Abstract

strain CHA0 is an effective biocontrol agent against soil-borne fungal plant pathogens. In this study, indole-3-acetic acid (IAA) biosynthesis in strain CHA0 was investigated. Two key enzyme activities were found to be involved: tryptophan side chain oxidase (TSO) and tryptophan transaminase. TSO was induced in the stationary growth phase. By fractionation of a cell extract of strain CHA0 on DEAE-Sepharose, two distinct peaks of constitutive tryptophan transaminase activity were detected. A pathway leading from tryptophan to IAA via indole-3-acetamide, which occurs in subsp. , was not present in strain CHA0. IAA synthesis accounted for ⩽1·5% of exogenous tryptophan consumed by resting cells of strain CHA0, indicating that the bulk of tryptophan was catabolized via yet another pathway involving anthranilic acid as an intermediate. Strain CHA750, a mutant lacking TSO activity, was obtained after Tn mutagenesis of strain CHA0. In liquid cultures (pH 6·8) supplemented with 10 m--tryptophan, growing cells of strains CHA0 and CHA750 synthesized the same amount of IAA, presumably using the tryptophan transaminase pathway. In contrast, resting cells of strain CHA750 produced five times less IAA in a buffer (pH 6·0) containing 1 mm--tryptophan than did resting cells of the wild-type, illustrating the major contribution of TSO to IAA synthesis under these conditions. In artificial soils at pH ~7 or pH ~6, both strains had similar abilities to suppress take-all disease of wheat or black root rot of tobacco. This suggests that TSO-dependent IAA synthesis is not essential for disease suppression.

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1991-10-01
2021-10-20
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References

  1. Bradford M. M. 1976; A rapid and sensitive method for the quantification of microgram quantities of protein utilizing the principle of protein-dye binding. Analytical Biochemistry 72:248–254
    [Google Scholar]
  2. Comai L., Kosuge T. 1980; Involvement of plasmid deoxyribo-nucleic acid in indoleacetic acid synthesis in Pseudomonas savastanoi . Journal of Bacteriology 143:950–957
    [Google Scholar]
  3. Défago G., Berling C. H., Burger U., Haas D., Kahr G., Keel C., Voisard C., Wirthner P., Wüthrich B. 1990; Suppressionof black root rot of tobacco and other root diseases by strains of Pseudomonas fluorescens potential applications and mechanisms. Biological Control of Soil-Borne Pathogens93–108 Hornby D., Cook R. J., Henis Y., Ko W. H., Rovira A. D., Schippers B., Scott P. R. Wallingford: CAB International;
    [Google Scholar]
  4. Défago G., Haas D. 1990; Pseudomonads as antagonists of soilborne plant pathogens: modes of action and genetic analysis. Soil Biochemistry 6249–291 Bollag J. M., Stotzky G. New York & Basel: Marcel Dekker;
    [Google Scholar]
  5. Frankenberger W. T., Poth M. 1988; l-Tryptophan trans-aminase of a bacterium isolated from the rhizosphere of Festuca octoflora (Gramineae). Soil Biology and Biochemistry 20:299–304
    [Google Scholar]
  6. Fujioka M., Morino Y., Wada H. 1970; Metabolism of phenylalanine. Methods in Enzymology 17a:585–596
    [Google Scholar]
  7. Haas D., Keel C, Laville J., Maurhofer M., Oberhänsli Th., Schnider U., Voisard C., Défago G. 1991; Secondary metabolites of Pseudomonas fluorescens strain CHAO involved in the suppression of root diseases. Advances in Molecular Genetics of Plant-Microbe Interactions I450–456 Hennecke I. H., Verma D. P. S. Dordrecht, Boston & London: Kluwer Academic Publishers;
    [Google Scholar]
  8. Hartmann A., Singh M., Klingmüller W. 1983; Isolation and characterization of Azospirillum mutants excreting high amounts of indoleacetic acid. Canadian Journal of Microbiology 29:916–923
    [Google Scholar]
  9. Ishimura Y. 1970; l-Tryptophan 2,3-dioxygenase (tryptophan pyrrolase) (Pseudomonas fluorescens). Methods in Enzymology 17a:429–438
    [Google Scholar]
  10. Kaper J. M., Veldstra H. 1958; On the metabolism of tryptophan by Agrobacterium tumefaciens . Biochimica et Biophysica Acta 30:401–420
    [Google Scholar]
  11. Keel C, Voisard C, Berling C. H., Kahr G., Défago G. 1989; Iron sufficiency, a prerequisite for the suppression of tobacco black root rot by Pseudomonas fluorescens strain CHAO under gnotobiotic conditions. Phytopathology 79:584–589
    [Google Scholar]
  12. Keel C, Wirthner Ph., Oberhänsli Th., Voisard C, Burger U., Haas D., Défago G. 1990; Pseudomonads as antagonists of plant pathogens in the rhizosphere: role of the antibiotic 2,4-di-acetylphloroglucinol in the suppression of black root rot of tobacco. Symbiosis 9:327–341
    [Google Scholar]
  13. Keel C, Maurhofer M., Oberhänsli Th., Voisard C, Haas D., Défago G. 1991; Role of 2,4-diacetylphloroglucinol in the suppression of take-all of wheat by a strain of Pseudomonas fluorescens . Developments in Agricultural and Managed-Forest Ecology 23, Biotic Interactions and Soil-Borne Diseases335–338 Beemster A. B. R., Bollen G. J., Gerlach M., Ruissen M. A., Schippers B., Tempel A. Amsterdam: Elsevier;
    [Google Scholar]
  14. King E. O., Ward M. K., Raney D. E. 1954; Two simple media for the demonstration of pyocyanin and fluorescein. Journal of Laboratory and Clinical Medicine 44:301–307
    [Google Scholar]
  15. Kuo T.-T., Kosuge T. 1970; Role of aminotransferase and indole-3-pyruvic acid in the synthesis of indole-3-acetic acid In Pseudomonas savastanoi . Journal of General and Applied Microbiology 16:191–204
    [Google Scholar]
  16. Loper J. E., Schroth M. N. 1986; Influence of bacterial sources of indole-3-acetic acid on root elongation of sugar beet. Phytopathology 76:386–389
    [Google Scholar]
  17. Müller M., Deigele C., Ziegler H. 1989; Hormonal interactions in the rhizosphere of maize (Zea mays L.) and their effects on plant development. Zeitschrift für Pflanzenernährung und Bodenkunde 152:247–254
    [Google Scholar]
  18. Narumiya S., Takai K., Tokuyama T., Noda Y., Ushiro H., Hayaishi O. 1979; A new metabolic pathway of tryptophan initiated by tryptophan side chain oxidase. Journal of Biological Chemistry 254:7007–7015
    [Google Scholar]
  19. Ornston L. N., Stanier R. Y. 1966; The conversion of catechol and protocatechuate to β-ketoadipate by Pseudomonas putida . Journal of Biological Chemistry 241:3776–3786
    [Google Scholar]
  20. Sandberg G., Crozier A., Ernstsen A. 1987; Indole-3-acetic acid and related compounds. The Principles and Practice of Plant Hormone Analysis 2169–301 Rivier L., Crozier A. London: Academic Press;
    [Google Scholar]
  21. Smiley R. W., Cook R. J. 1973; Relationship between take-all of wheat and rhizosphere-pH in soils fertilized with ammonium vs. nitrate-nitrogen. Phytopathology 63:882–890
    [Google Scholar]
  22. Stanisich V., Holloway B. W. 1972; A mutant sex factor of Pseudomonas aeruginosa . Genetical Research 19:91–108
    [Google Scholar]
  23. Stutz E. W., Défago G., Kern H. 1986; Naturally occurring fluorescent pseudomonads involved in suppression of black root rot of tobacco. Phytopathology 76:181–185
    [Google Scholar]
  24. Surico G., Iacobellis N. S., Sisto N. S. 1985; Studies on the role of indole-3-acetic acid and cytokinins in the formation of knots on olive and oleander plants by Pseudomonas syringae pv. savastanoi . Physiological Plant Pathology 26:309–320
    [Google Scholar]
  25. Takai K., Hayaishi O. 1987; Purification and properties of tryptophan side chain oxidase types I and II from Pseudomonas . Methods in Enzymology 142:195–216
    [Google Scholar]
  26. Tien T. M., Gaskins M. H., Hubbell D. H. 1979; Plant growth substances produced by Azospirillum brasilense and their effect on the growth of pearl millet (Pennisetum americanum L.). Applied and Environmental Microbiology 167:371–378
    [Google Scholar]
  27. Voisard C, Keel C, Haas D., Défago G. 1989; Cyanide production by Pseudomonas fluorescens helps suppress black root rot of tobacco under gnotobiotic conditions. EMBO Journal 8:351–358
    [Google Scholar]
  28. Weller D. M., Cook R. J. 1983; Suppression of take-all of wheat by seed treatments with fluorescent pseudomonads. Phytopathology 73:463–169
    [Google Scholar]
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