【作者】 许鹏亮；

【导师】 李晓林；

【作者基本信息】 中国农业大学 ， 植物营养学， 2005， 硕士

【摘要】 本研究利用盆栽和分室根箱培养方式探讨了由Glomus mosseae和Medicago truncatula形成的丛枝菌根共生体的抗砷酸毒害的机理;并在分室根箱试验中引入Glomus intraradices,以比较两菌种在抗砷能力上的差异。 主要的研究结论如下: 1.与宿主植物M.truncatula相比,AM真菌G.mosseae的抗砷酸的能力较强。G.mosseae的侵染可提高M.truncatula的抗砷酸能力,表现为接种处理植株的EC₅₀值提高了2倍。在砷酸毒害的条件下,接种G.mosseae使得M. truncatula地上部的磷水平维持在较为稳定的水平上,而不接种植物地上部的磷水平却随着土壤砷浓度的增加而急剧下降。在中、高砷添加水平处(50,100和200mg kg^-1),接种G.mosseae能显著的降低宿主地上部和地下部的砷浓度。试验表明,G.mosseae通过改善磷营养状况和限制砷吸收,达到提高宿主M.truncatula的抗砷酸能力。 2.在低砷添加水平下(10mg kg^-1),接种G.mosseae对M.truncatula的地上部和地下部的砷浓度无显著影响;但在中、高砷添加水平下(50,100和200mg kg^-1),接种G.mosseae可显著降低植物地上部和地下部的砷浓度。 3.G.mosseae和G.intraradices对砷的转运能力均很有限,但两者之间仍在诸多方面有着明显的差异。与G.intraradices相比,G.mosseae的抗砷酸能力更强。虽然G.mosseae和G.intraradices都能提高宿主植物M.truncatula的磷水平,但G.mosseae对宿主的供磷能力强于G.intraradices。两个菌种的根外菌丝的分布状况也很不相同:G.mosseae的菌丝主要分布于其宿主根的附近,而G.intraradices的菌丝则均匀的分布于离宿主根较远的土壤空间。更多还原

【Abstract】 We used conventional plant pots and compartmented rhizoboxes to investigate the effects of two arbuscular mycorrhizal fungi on uptake of arsenate by Medicago truncatula. In the pot experiment we inoculated the host plant with Glomus mosseae and in the rhizobox experiment we compared G mosseae with Glomus intraradices.Hyphal density was unaffected by As even at the highest application rate of 200 mg kg-1 As to the soil which strongly depressed the biomass of mycorrhizal plants and non-myconhizal controls. Myconhizal inoculation increased the EC50 of both shoot and root dry weights about threefold, perhaps by enhancing host plant tolerance to arsenate. Shoot P concentrations were maintained at relatively constant values following inoculation with G. mosseae but decreased sharply in non-mycorrhizal plants with increasing arsenate addition level. At intermediate and high arsenate addition levels (50, 100 and 200 mg kg-1), inoculation significantly reduced the shoot and root As concentrations. Thus, AM fungal colonization may have conferred enhanced tolerance to arsenate on the host plant by enhancing P nutrition and restricting root As uptake.At low soil arsenate levels (0 and 10 mg kg-1 added As) there was no significant difference in As content between mycorrhizal and non-myconhizal plants. However, at mtermaediate and high arsenate addition levels inoculation significantly reduced the shoot and root As concentrations.Although inoculation with either G. mosseae or G intraradices resulted in limited As translocation to the two fungi, G. mosseae appeared to be more tolerant to arsenate and to provide M. truncatula with more P than did G intraradices. Furthermore, the hyphal distributions of the two fungi differed greatly. While most of the external hyphae of G. mosseae were found near the host roots, the extrametrical hyphae of G intraradices tended to extend greater distances away from the roots.更多还原