Phosphorus source alters host plant response to ectomycorrhizal diversity

TY - JOUR

T1 - Phosphorus source alters host plant response to ectomycorrhizal diversity

AU - Baxter, James W.

AU - Dighton, John

N1 - Funding Information: Acknowledgements We would like to thank Christine Edly for her diligence in establishing and maintaining the mycorrhizal plants and conducting plant nutrient analyses. Cultures of Pisolithus tinctorius and Piloderma bicolor were generously supplied by O.K. Miller and Cenococcum geophilum was provided by Amy Tuininga. Thanks are also extended to the two anonymous reviewers whose comments significantly improved the manuscript. This research was funded by a National Science Foundation grant IBN-9723254.

PY - 2005/11

Y1 - 2005/11

N2 - We examined the influence of phosphorus source and availability on host plant (Pinus rigida) response to ectomycorrhizal diversity under contrasting P conditions. An ectomycorrhizal richness gradient was established with equimolar P supplied as either inorganic phosphate or organic inositol hexaphosphate. We measured growth and N and P uptake of individual P. rigida seedlings inoculated with one, two, or four species of ectomycorrhizal fungi simultaneously and without mycorrhizas in axenic culture. Whereas colonization of P. rigida by individual species of ectomycorrhizal fungi decreased with increasing fungal richness, colonization of all species combined increased. Plant biomass and N content increased across the ectomycorrhizal richness gradient in the organic but not the inorganic P treatment. Plants grown under organic P conditions had higher N concentration than those grown under inorganic P conditions, but there was no effect of richness. Phosphorus content of plants grown in the organic P treatment increased with increasing ectomycorrhizal richness, but there was no response in the inorganic P treatment. Phosphorus concentration was higher in plants grown at the four-species richness level in the organic P treatment, but there was no effect of diversity under inorganic P conditions. Overall, few ectomycorrhizal composition effects were found on plant growth or nutrient status. Phosphatase activities of individual ectomycorrhizal fungi differed under organic P conditions, but there was no difference in total root system phosphatase expression between the inorganic or organic P treatments or across richness levels. Our results provide evidence that plant response to ectomycorrhizal diversity is dependent on the source and availability of P.

AB - We examined the influence of phosphorus source and availability on host plant (Pinus rigida) response to ectomycorrhizal diversity under contrasting P conditions. An ectomycorrhizal richness gradient was established with equimolar P supplied as either inorganic phosphate or organic inositol hexaphosphate. We measured growth and N and P uptake of individual P. rigida seedlings inoculated with one, two, or four species of ectomycorrhizal fungi simultaneously and without mycorrhizas in axenic culture. Whereas colonization of P. rigida by individual species of ectomycorrhizal fungi decreased with increasing fungal richness, colonization of all species combined increased. Plant biomass and N content increased across the ectomycorrhizal richness gradient in the organic but not the inorganic P treatment. Plants grown under organic P conditions had higher N concentration than those grown under inorganic P conditions, but there was no effect of richness. Phosphorus content of plants grown in the organic P treatment increased with increasing ectomycorrhizal richness, but there was no response in the inorganic P treatment. Phosphorus concentration was higher in plants grown at the four-species richness level in the organic P treatment, but there was no effect of diversity under inorganic P conditions. Overall, few ectomycorrhizal composition effects were found on plant growth or nutrient status. Phosphatase activities of individual ectomycorrhizal fungi differed under organic P conditions, but there was no difference in total root system phosphatase expression between the inorganic or organic P treatments or across richness levels. Our results provide evidence that plant response to ectomycorrhizal diversity is dependent on the source and availability of P.

KW - Inositol hexaphosphate (Phytate)

KW - Mycorrhizal diversity

KW - Nutrient uptake

KW - Phosphorus availability

KW - Plant growth

KW - Species richness

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U2 - https://doi.org/10.1007/s00572-005-0359-0

DO - https://doi.org/10.1007/s00572-005-0359-0

M3 - Article

C2 - 15809869

SN - 0940-6360

VL - 15

SP - 513

EP - 523

JO - Mycorrhiza

JF - Mycorrhiza

IS - 7

ER -