关键词: 丛枝菌根真菌, 氮素, 转运途径

Abstract:

Arbuscular mycorrhizal fungi （AMF） could form symbionts with host plants and were widely found in terrestrial ecosystems， and AMF could significantly enhance the nitrogen （N） absorption capacity of host plants. The symbiosis of AMF with hosts could promote the absorption of N of plants through direct and indirect ways. The direct way was to improve the root traits， expand the total area and active absorption area of root by symbiosis of AMF and hosts. In addition， mycelium was formed in plant roots to expand the exploration area of soil. At the same time， extraneous mycelia could also form mycelial bridge between host roots to improve the N absorption capacity and N communication between hosts. The indirect way was that mycorrhizal symbiosis could promote the increase of host’s root secretion and mycelial secretion， and improve soil Nabsorption of hosts. In addition， mycelium could carry a large number of bacteria， and mycelium secretions could stimulate the growth and activity of microorganisms， and then changed the microbial composition of host’s roots. Meanwhile， the interaction between AMF and rhizobium could improve the host’s ability to fix N and absorb N. In addition of affecting the host’s absorption of N， AMF could also affect the host’s transport pathway of N. It showed the extraneous mycelia in mycorrhizal symbionts absorbed inorganic N in the soil and converted the inorganic N into arginine （Arg）， which was transported to the mycelia in the root through mycelia， where Arg was decomposed into urea and ornithine （Orn）， and NH{}_{\mathrm{4}}^{+}-N was formed again through the cycle of ornithine. And the NH{}_{\mathrm{4}}^{+}-N was transfered to host cells via ammonium transporter （AMT） for plant growth. The effects of AMF on nitrogen uptake and N transport in plants were reviewed， which provided a reference for mycorrhizal interaction in plant N uptake and transport.

Key words: arbuscular mycorrhizal fungi, nitrogen, route of transit