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New Phytol. 2017 Apr;214(1):400-411. doi: 10.1111/nph.14325. Epub 2016 Nov 21.

Transfer of 13 C between paired Douglas-fir seedlings reveals plant kinship effects and uptake of exudates by ectomycorrhizas.

Author information

1
Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4.
2
School of Biological Sciences, University of Reading, Harborne Building, Whiteknights, Reading, RG6 6AS, UK.
3
Department of Microbiology & Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada, V6T 1Z3.

Abstract

Processes governing the fixation, partitioning, and mineralization of carbon in soils are under increasing scrutiny as we develop a more comprehensive understanding of global carbon cycling. Here we examined fixation by Douglas-fir seedlings and transfer to associated ectomycorrhizal fungi, soil microbes, and full-sibling or nonsibling neighbouring seedlings. Stable isotope probing with 99% 13 C-CO2 was applied to trace 13 C-labelled photosynthate throughout plants, fungi, and soil microbes in an experiment designed to assess the effect of relatedness on 13 C transfer between plant pairs. The fixation and transfer of the 13 C label to plant, fungal, and soil microbial tissue was examined in biomass and phospholipid fatty acids. After a 6 d chase period, c. 26.8% of the 13 C remaining in the system was translocated below ground. Enrichment was proportionally greatest in ectomycorrhizal biomass. The presence of mesh barriers (0.5 or 35 μm) between seedlings did not restrict 13 C transfer. Fungi were the primary recipients of 13 C-labelled photosynthate throughout the system, representing 60-70% of total 13 C-enriched phospholipids. Full-sibling pairs exhibited significantly greater 13 C transfer to recipient roots in two of four Douglas-fir families, representing three- and fourfold increases (+ c. 4 μg excess 13 C) compared with nonsibling pairs. The existence of a root/mycorrhizal exudation-hyphal uptake pathway was supported.

KEYWORDS:

carbon (C) allocation; ectomycorrhizas; host relatedness; interior Douglas-fir; phospholipid fatty acid (PLFA); stable-isotope probing

PMID:
27870059
DOI:
10.1111/nph.14325
[Indexed for MEDLINE]
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