摘 要 ：本文意在探究外源碳对丛枝菌根（arbuscular mycorrhiza, AM）真菌吸收氮源合成精氨酸(Arg)的影响。采用三室隔离盆栽培养系统，以高粱（Sorghum bicolor L. Moench）为宿主植物，接种AM真菌Glomus intraradices，在菌丝室施加4 mmol/L的NH4NO3，同时在根室施加不同形式的碳源，测定分析不同外源碳条件下根外菌丝体（ERM）、菌根和植物茎叶中的Arg含量和总氮含量。结果表明ERM和菌根中的Arg含量远远高于茎叶中；虽然不同形式外源碳提高了AM真菌的ERM干重和菌根侵染率，但是葡萄糖降低了ERM、菌根和茎叶中的Arg含量，蔗糖和甘油对Arg含量没有显著的影响，只有外源Arg和谷氨酰胺（Gln）使ERM中的Arg含量显著增加；不同外源碳对菌根和茎叶的总氮含量没有显著影响。由上述结果分析可知在根室施加外源碳对AM真菌的氮代谢和宿主植物氮素营养水平没有显著影响，Arg合成所需的碳可能大多来自宿主植物供给的碳水化合物；但是施加外源碳能够促进AM真菌的生长繁殖。
Abstract:The aim of this paper is to investigate the effects of different forms of exogenous organic matters on the assimilation of nitrogen and production of arginine (Arg) by arbuscular mycorrhizal (AM) fungus. AM fungi (Glomus intraradices) were inoculated to the host plant (Sorghum bicolor L. Moench) and grown in the three-compartment pot culture system, 4mmol/L NH4NO3 was added into the mycelium compartment, and different forms of carbons were added into the root compartment. The Arg and total nitrogen contents were determined and analysed in extraradical mycelium (ERM), mycorrhizal roots and shoots separately. The results show that the contents of Arg in ERM and mycorrhizal roots are significantly higher than that those in shoots. The dry weight of ERM and root infection rate are increased under the adding of different forms of organic matters, while the Arg contents in ERM, mycorrhizal roots and shoots are reduced under the adding of glucose. The production of Arg is not significantly affected under the adding of sucrose and glycerol, while the Arg content in ERM is significantly increased under the adding of external Arg and glutamine (Gln). The different forms of carbons have no significant effects on total nitrogen contents in mycorrhizal roots and shoots. Therefore, the carbon for Arg biosynthesis is mostly derived from the carbohydrates of the host plants supply, however the exogenous carbon could promote the growth of AM fungus.