Plant and Soil

, Volume 295, Issue 1, pp 115–125

Decreasing prevalence of rhizosphere IAA producing and seedling root growth promoting bacteria with barley development irrespective of protozoan grazing regime

  • Mette Vestergård
  • Lisa Bjørnlund
  • Frédéric Henry
  • Regin Rønn
Regular Article

DOI: 10.1007/s11104-007-9267-8

Cite this article as:
Vestergård, M., Bjørnlund, L., Henry, F. et al. Plant Soil (2007) 295: 115. doi:10.1007/s11104-007-9267-8

Abstract

Barley was grown in soil with either bacteria and a mixed protozoan community (Mixed protozoa) or bacteria and a single vahlkampfiid amoebal species (Single amoeba). We assessed the influence of plant age (day 29, 43 and 57 after sowing) on two aspects of rhizosphere bacterial functioning: (1) the proportion of indole-3-acetic acid (IAA) producing bacteria and (2) the effect of mixed rhizosphere bacterial assemblages on barley seedling root growth in an agar based assay. The proportion of IAA producers was significantly lower at day 57 than at day 29 and 43, and mixed bacterial assemblages extracted from rhizospheres of 29 days old plants were significantly less harmful to seedling growth than bacterial assemblages from older plants. Hence both assays indicated that bacterial communities from rhizospheres of older plants were less beneficial for root growth than bacterial communities from younger plants. Genetic fingerprinting of rhizosphere bacterial communities was compared by use of length heterogeneity polymerase chain reaction (LH-PCR). This analysis showed a clear succession from the inoculum bacterial community with a rather low diversity to a community with much higher diversity at day 29. However, diversity did not change after day 29, and no relationship between protozoan treatment nor plant age and genetic fingerprinting was found.

Keywords

Bacterial metabolitesFlagellatesLH-PCRPlant deleterious bacteriaPGPR

Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • Mette Vestergård
    • 1
  • Lisa Bjørnlund
    • 2
  • Frédéric Henry
    • 1
  • Regin Rønn
    • 1
  1. 1.Section of Terrestrial Ecology, Department of BiologyUniversity of CopenhagenCopenhagen KDenmark
  2. 2.Section of Genetics and Microbiology, Department of Ecology, Faculty of Life SciencesUniversity of CopenhagenFrederiksberg CDenmark