Plant-mediated partner discrimination in ectomycorrhizal mutualisms

• Published in: Mycorrhiza 2019-03, Vol.29 (2), p.97-111
• Main Authors: Bogar, Laura, Peay, Kabir, Kornfeld, Ari, Huggins, Julia, Hortal, Sara, Anderson, Ian, Kennedy, Peter
• Format: Article
• Language: English
• Subjects: Agriculture; BASIC BIOLOGICAL SCIENCES; Biomedical and Life Sciences; Carbon; Carbon 13; Carbon cycle; Colonization; Ecological effects; Ecology; Ectomycorrhiza; Ectomycorrhizas; Experiments; Forestry; Fungi; Larix - microbiology; Larix occidentalis; Life Sciences; Microbiology; Mycorrhizae - physiology; Nitrogen; Original Article; Partner choice; Pinus - microbiology; Pinus muricata; Plant communities; Plant Sciences; Reinforcement; Seedlings; Seedlings - microbiology; Soil Microbiology; Spores; Stable isotope enrichment; Suillus; Symbiosis
• ISSN: 0940-6360; 1432-1890
• DOI: 10.1007/s00572-018-00879-7

Although ectomycorrhizal fungi have well-recognized effects on ecological processes ranging from plant community dynamics to carbon cycling rates, it is unclear if plants are able to actively influence the structure of these fungal communities. To address this knowledge gap, we performed two complementary experiments to determine (1) whether ectomycorrhizal plants can discriminate among potential fungal partners, and (2) to what extent the plants might reward better mutualists. In experiment 1, split-root Larix occidentalis seedlings were inoculated with spores from three Suillus species ( S. clintonianus , S. grisellus , and S. spectabilis ). In experiment 2, we manipulated the symbiotic quality of Suillus brevipes isolates on split-root Pinus muricata seedlings by changing the nitrogen resources available, and used carbon-13 labeling to track host investment in fungi. In experiment 1, we found that hosts can discriminate in multi-species settings. The split-root seedlings inhibited colonization by S. spectabilis whenever another fungus was available, despite similar benefits from all three fungi. In experiment 2, we found that roots and fungi with greater nitrogen supplies received more plant carbon. Our results suggest that plants may be able to regulate this symbiosis at a relatively fine scale, and that this regulation can be integrated across spatially separated portions of a root system.