RESEARCH REPORTS FROM INSTITUTE FOR AGRO-MICROBIOLOGY, Vol. 4, 2000 p.15-28
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ORIGINAL ARTICLE
2.Analysis of Nitrogen Isotope Ratios in the Symbiotic Systems of Pinus densiflora Inoculated with Ectomycorrhizal Fungus, Suillus granulatus
Naoko Tokuchi*1, Ayato Kohzu*2, and Takahiro Tateishi*1(*1 Graduate School of Agriculture, Kyoto University, *2 Center for Ecological Research, Kyoto University)
Comparison of the 15N natural abundance between the seedlings of Pinus densiflora Sieb. et Zucc. which was uninoculated and inoculated with ectomycorrhizal fungus, Suillus granulatus (L:Fr.) Kuntze was performed using ectomycorrhizal symbiotic microcosm system. 15Nitrogen isotope ratio (δ15N) of needles, root tips without infection and mycorrhizal mycelial mat in the seedbeds of P. densiflora infected by S. granulatus was analyzed compared with uninfected ones by isotope mass spectrometer equipped with C and N analyzer. 15N depletion in the needles of P. densiflora infected by S. granulatus and 15N enrichment in the uninfected ones were clear. 15N enrichment in the mycelial mat relative to the needles of P. densiflora infected by S. granulatus was also observed. Furthermore N content of the needles of infected pines was lower than that of uninfected ones. Considering the δ15N value of the primary nitrogen source, nitrogen isotope fractionation during the nitrogen transport from mycorrhizal fungi to host plants can explain these difference of the 15N natural abundance.
Keywords: 15N, natural abundance, ectomycorrhizae, Pinus densiflora, nitrogen transport, Suillus granulatus