Letter | Published:

Enhanced plant growth by siderophores produced by plant growth-promoting rhizobacteria

Naturevolume 286pages885886 (1980) | Download Citation



Specific strains of the Pseudomonas fluorescens-putida group have recently been used as seed inoculants on crop plants to promote growth and increase yields. These pseudomonads, termed plant growth-promoting rhizobacteria (PGPR), rapidly colonize plant roots of potato, sugar beet and radish, and cause statistically significant yield increases up to 144% in field tests1–5. These results prompted us to investigate the mechanism by which plant growth was enhanced. A previous study indicated that PGPR increase plant growth by antagonism to potentially deleterious rhizoplane fungi and bacteria, but the nature of this antagonism was not determined6. We now present evidence that PGPR exert their plant growth-promoting activity by depriving native microflora of iron. PGPR produce extracellular siderophores (microbial iron transport agents)7 which efficiently complex environmental iron, making it less available to certain native microflora.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1

    Kloepper, J. W. & Schroth, M. N. in Proc 4th int. Conf. Plant Pathogenic Bacteria Vol. 2 (ed. Station de Pathologie Végétale et Phytobactériologie) 879–882 (Gibert-Clarey, Tours, 1978).

  2. 2

    Kloepper, J. W. & Schroth, M. N. Phytopathology (in the press).

  3. 3

    Suslow, T. V. thesis, Univ. California (1980).

  4. 4

    Suslow, T. V., Kloepper, J. W., Schroth, M. N. & Burr, T. J. Calif. Agric. 33, 15–17 (1979).

  5. 5

    Burr, T. J., Schroth, M. N. & Suslow, T. Phytopathology 68, 1377–1383 (1978).

  6. 6

    Kloepper, J. W. thesis, Univ. California (1979).

  7. 7

    Neilands, J. B. in Iron in Biochemistry and Medicine (eds Jacobs, A. & Worwood, M.) (Academic, New York, in the press).

  8. 8

    King, E. O., Ward, M. K. & Raney, D. E. J. Lab. clin. Med. 44, 301–307 (1954).

  9. 9

    Garibaldi, J. A. J. Bact. 105, 1036–1038 (1971).

  10. 10

    Meyer, J. M. & Abdallah, M. A. J. gen. Microbiol. 107, 319–328 (1978).

  11. 11

    Maurer, B., Müller, A., Keller-Schierlein, W. & Zähner, H. Arch. Mikrobiol. 60, 326–339 (1968).

  12. 12

    Ong, S. A., Peterson, T. & Neilands, J. B. J. biol. Chem. 254, 1860–1865 (1979).

  13. 13

    Cox, C. D. & Graham, R. J. Bact. 137, 357–364 (1979).

  14. 14

    Liu, P. V. & Shokrani, F. Infect. Immun. 22, 878–890 (1978).

  15. 15

    McCracken, A. R. & Swinburne, T. R. Physiol. Pl. Path. 15, 331–340 (1979).

  16. 16

    Huisman, O. C., Ashworth, L. J. & Harper, D. Phytopathology (submitted).

Download references

Author information


  1. Department of Plant Pathology, University of California, Berkeley, California, 94720

    • Joseph W. Kloepper
    •  & Milton N. Schroth
  2. Department of Chemistry, University of California, San Diego, La Jolla, California, 92093

    • John Leong
    •  & Martin Teintze


  1. Search for Joseph W. Kloepper in:

  2. Search for John Leong in:

  3. Search for Martin Teintze in:

  4. Search for Milton N. Schroth in:

About this article

Publication history



Issue Date



Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.