title: Growth and photosynthetic responses of ectomycorrhizal pine seedlings exposed to elevated Cu in soils.
abstract: It is still controversial whether ectomycorrhizal (ECM) mycelia filter out toxic metals in nutrient absorption of host trees. In this study, pine (Pinus densiflora) seedlings colonized by Cu-sensitive and Cu-tolerant ECM species were exposed to a wide spectrum of soil Cu concentrations to investigate functions of ECM fungi under Cu stress. The photosynthetic rates of intact needles were monitored in situ periodically. The biomass and elements of plants were also measured after harvest. The ameliorating effect of ECM infection on host plants exposed to toxic stress was metal concentration specific. Under lower-level Cu stress, ECM fungi increased seedling performance, while ECM seedlings accumulated more Cu than nonmycorrhizal (NM) seedlings. Under higher-level Cu stress, photosynthesis decreased well before visible symptoms of Cu toxicity appeared. The reduced photosynthesis and biomass in ECM seedlings compared to NM seedlings under higher Cu conditions were also accompanied by lower phosphorus in needles. There was no marked difference between the two fungal species. Our results indicate that the two ECM fungi studied in our system may not have an ability to selectively eliminate Cu in nutrient absorption and may not act as effective barriers that decrease toxic metal uptake into host plants.
authors.affiliation: The Collaborated Lab. of Plant Molecular Ecology (between College of Life Sciences of Nanjing Agricultural University and Asian Natural Environmental Science Center of the University of Tokyo), Nanjing Agricultural University, Nanjing, 210095, China.
authors.forename: Yahua
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Natural Environmental Studies, Graduate School of Frontier Science, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8563, Japan.
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Nara
authors.affiliation: The Collaborated Lab. of Plant Molecular Ecology (between College of Life Sciences of Nanjing Agricultural University and Asian Natural Environmental Science Center of the University of Tokyo), Nanjing Agricultural University, Nanjing, 210095, China.
authors.forename: Zhugui
authors.initials: Z
authors.lastname: Wen
authors.affiliation: The Collaborated Lab. of Plant Molecular Ecology (between College of Life Sciences of Nanjing Agricultural University and Asian Natural Environmental Science Center of the University of Tokyo), Nanjing Agricultural University, Nanjing, 210095, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Shi
authors.affiliation: The Collaborated Lab. of Plant Molecular Ecology (between College of Life Sciences of Nanjing Agricultural University and Asian Natural Environmental Science Center of the University of Tokyo), Nanjing Agricultural University, Nanjing, 210095, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Xia
authors.affiliation: The Collaborated Lab. of Plant Molecular Ecology (between College of Life Sciences of Nanjing Agricultural University and Asian Natural Environmental Science Center of the University of Tokyo), Nanjing Agricultural University, Nanjing, 210095, China.
authors.forename: Zhenguo
authors.initials: Z
authors.lastname: Shen
authors.affiliation: The Collaborated Lab. of Plant Molecular Ecology (between College of Life Sciences of Nanjing Agricultural University and Asian Natural Environmental Science Center of the University of Tokyo), Nanjing Agricultural University, Nanjing, 210095, China. lian@anesc.u-tokyo.ac.jp.|Asian Natural Environmental Science Center, The University of Tokyo, 1-1-8 Midori-cho, Nishitokyo, Tokyo, 188-0002, Japan. lian@anesc.u-tokyo.ac.jp.
authors.forename: Chunlan
authors.initials: C
authors.lastname: Lian
mesh_terms: D003300:Copper / Q000378:metabolism*; D038821:Mycorrhizae / Q000502:physiology*; D010788:Photosynthesis / Q000187:drug effects*; D028223:Pinus / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology*; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology; D012989:Soil Pollutants / Q000378:metabolism*
chemical_list: D012989:Soil Pollutants; D003300:Copper
keywords: Copper uptake; ECM fungi; Heavy metal-contaminated soils; Metal toxicity; Photosynthesis; Pine (Pinus densiflora)