四种外生菌根真菌对黑松吸收转运镉的影响
时间:2018-08-07 08:55 来源:毕业论文 作者:毕业论文 点击:次
| 摘要：选取了4种外生菌根真菌（Ectomycorrhizal fungi, EMF）：紫蜡蘑(Laccaria amethystina, La)，彩色豆马勃(Pisolithus tinctorius, Pt)，土生空团菌(Cenococcum geophilum, Cg)，漆蜡蘑(Laccaria laccata, Ll)。纯培养试验表明，4种菌的Cd耐性由高到低分别为：La > Ll > Pt > Cg，它们的Cd半抑制浓度（EC50）分别是：12.50，7.75，2.68，0.34 mg L-1。将这4种菌分别接种日本黑松（Pinus thunbergii Parl.），研究了土壤外源添加不同浓度Cd（0，30，75，150 mg kg-1）处理后EMF对宿主植物吸收转运Cd的影响。结果表明，与非接菌对照比，接种4种EMF均能提高宿主植物对Cd的耐性。此外，菌根的外延菌丝能将根袋外的Cd吸附固定到植物根际及吸收转运至植物体内。并且菌株Cd耐性越高，根际富集的重金属以及植物体内积累的Cd含量越高，表现了促进宿主植物吸收重金属的效应，表明了外生菌根真菌并不能充当屏障作用抑制宿主植物对重金属的吸收。菌根真菌提高宿主植物的Cd耐性，并非通过降低吸收，而是通过改善植物营养状况，促进其生长从而稀释富集到植物体内的Cd所产生的。26680 毕业论文关键词：外生菌根真菌；镉；宿主植物；促进吸收 Effects of four Ectomycorrhizal Fungi on Absorption and Transport of Cadmium in Pinus thunbergii Parl Abstract：We examined the effects of four ectomycorrhizal fungi (EMF), Laccaria amethystina (La), Pisolithus tinctorius (Pt), Cenococcum geophilum (Cg), and Laccaria laccata (Ll), on the absorption and transport of cadmium (Cd) in plant hosts. First, in pure culture experiments, we determined the Cd tolerance of the EMF species, which was, from highest to lowest, La > Ll > Pt > Cg, with 50% inhibition concentration (EC50) values of 12.50, 7.75, 2.68, and 0.34 mg kg−1, respectively. Then, in root bag experiments, Pinus thunbergii Parl. seedlings either alone or inoculated with each of the four EMF species were exposed to soil amended with 0, 30, 75, or 150 mg kg−1 Cd. Inoculation with EMF improved the host plants’ Cd tolerance compared to the non-inoculated seedlings. Furthermore, external hyphae were able to absorb Cd outside the root bag and transfer it to the host plant, and strains with higher Cd tolerances were associated with greater heavy metal accumulation in both the rhizosphere and the whole plants. These results demonstrate the role of EMF in promoting heavy metal absorption by host plants and show that EMF does not inhibit heavy metal absorption in host plants. Instead, EMF increases heavy metal tolerance in host plants by improving plant nutritional status and promoting plant growth, diluting heavy metal concentrations in the process. Key words: Ectomycorrhizal fungi; cadmium; host plants; promote absorption 目 录 摘要 1 关键词1 Abstract 1 Key words 1 引言1 1材料与方法2 1.1外生菌根真菌的Cd耐性2 1.2外生菌根黑松准备2 1.3基质准备2 1.4实验设计3 1.5测定指标及方法3 1.6数据处理4 2结果与分析 4 2.1 4种EMF对Cd的耐性 4 2.2菌丝生长情况 4 2.3生物量5 2.4植物体内Cd浓度 6 2.5 Cd的固定6 2.6植物营养水平7 3 讨论 8 致谢9 参考文献 10 四种外生菌根真菌对黑松吸收转运镉的影响重金属是指密度大于5 g cm-3的元素，主要包括过渡金属、部分类金属、镧系以及锕系元素[1]。重金属在土壤中自然发生并且浓度变化很大。尤其是因为工业活动的迅速扩张和重金属的难降解性，它们在环境中不断积累[2]。Cd作为一种生物非必需重金属元素，生物半衰期很长，是一类存在较广的衡量环境污染物[3]。土壤中的Cd能被植物吸收并在可食用部位积累，最终会通过食物链进入人体内，给人类健康带来了巨大的威胁 [4]。因此，修复Cd污染土壤对于人类的健康和环境的保护尤其急迫。 (责任编辑：qin) |