Different soil moisture conditions change the outcome of the ectomycorrhizal symbiosis between Rhizopogon species and Pinus muricata

Peter G. Kennedy, Kabir G. Peay

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63 Scopus citations


The outcome of species interactions often depends on the environmental conditions under which they occur. In this study, we tested how different soil moisture conditions affected the outcome of the ectomycorrhizal symbiosis between three Rhizopogon species and Pinus muricata in a factorial growth chamber experiment. We found that when grown in 7% soil moisture conditions, ectomycorrhizal plants had similar biomass, photosynthesis, conductance, and total leaf nitrogen as non-mycorrhizal plants. However, when grown at 13% soil moisture, ectomycorrhizal plants had significantly greater shoot biomass, higher photosynthetic and conductance rates, and higher total leaf nitrogen than non-mycorrhizal plants. The differences in plant response by mycorrhizal status in the two soil moisture treatments corresponded with evidence of water limitation experienced by the fungi, which had much lower colonization at 7% compared to 13% soil moisture. Our results suggest that the outcome of the ectomycorrhizal symbiosis can be context-dependent and that fluctuating environmental conditions may strongly affect the way plants and fungi interact.

Original languageEnglish (US)
Pages (from-to)155-165
Number of pages11
JournalPlant and Soil
Issue number1-2
StatePublished - Feb 2007

Bibliographical note

Funding Information:
Acknowledgments We thank the Pt. Reyes National Seashore for use of their land; Tom Bruns, Todd Dawson, and Matteo Garbelotto for their advice and logistical support; C. Benneman for assistance with the growth chamber experiment; S. Mambelli for assistance with the isotopic analyses. M. Bidartondo and members of both the Bruns and Garbelotto labs at UC Berkeley for constructive criticism on earlier drafts of this manuscript. Financial support for this project was provided by a National Science Foundation doctoral dissertation improvement grant to P.G. Kennedy, T.D. Bruns, and W.P. Sousa (DEB 0309152), a National Parks Ecological Research Fellowship to P.G. Kennedy, and a NASA Earth Systems Science Fellowship to K.G. Peay.


  • Context-dependence
  • Drought
  • Ectomycorrhiza
  • Fungi
  • Mutualism
  • Water


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