Study On The Efficency And Mechanism Of Nitrogen Absorption And Transport In The AMF-canna Symbiotic System

Canna indica L.is one of the wetland plants which are most widely used to remove the nitrogen and phosphorus in water remediation projects.Studying the mechanism of nitrogen absorption efficiency of canna is one of the most important element task which is crucial for theoretical research and practical application value.Based on the investigation of type of AMF?Arbuscular Mycorrhizal Fungi?that infects canna used here,this study takes Canna indica L.var.flava Roxb.as research object to test the nitrogen absorption effectiveness of AMF-canna and the impact of AMF and form of inorganic nitrogen on nitrogen transport protein genes.The main work and content are as follow:Illumina high-throughput sequencing showed that the type of AMF here belonged to the family of Glomeraceae.Microscopic examination improved the hypha colonization rate was about 5.66±1.08%for seeding stage in spring,but it could be much more higher for adult stage in autumn,which was about 53.89±1.43%.Then we analysed the absorption effectiveness of AMF-canna symbiotic system under different combining form of NH₄⁺-N and NO₃^--N by solution culture.AMF had no obvious significance on NO₃^--N absorption of roots of canna?P>0.05?.But it improved absorptivity by63%for NO₃^--N absorption under low concentration,while AMF had inhibitional effect on absorptivity under high concentration so that of AMF-canna was 7%lower than single canna.When NH₄⁺-N and NO₃^--N applied together?1:1?,the absorption effectiveness is positively correlated with concentrate change,which could be 99.63%and 99.50%for NH₄⁺-N and NO₃^--N respectively.N¹⁵ isotopic marking test and model calculation of its results showed that transport coefficient of single canna was-0.923 and that of AMF was 0.601.This reflected the internal hyphae could have inhinitional impact on effectiveness of nitrogen absorption and transport of canna.Real-time fluorescence quantification Polymerase Chain Reaction showed that expression of two types of NH₄⁺-N transport protein genes,namely AMT1 and AMT2,could be improved as the increase of concentration while NH₄⁺-N and NO₃^--N existed together.Meanwhile AMF could significantly improve the expression of AMT2 and have no obvious impact on NRT2,which is one type of NO₃^--N transport protein genes.When either NH₄⁺-N or NO₃^--N was applied,AMF only improved effectiveness significantly under low concentrations.AMT1mainly expressed in the internal cells of root to dominate the transport of NH₄⁺-N,while AMT2was in the epidermic cells to lead the absorption process from the outside and its expression could be restrained by internal hyphae.When only one type of inorganic nitrogen supplied,the other type of nitrogen transport protein genes would express vigorously.It was inferred that NH₄⁺and NO₃^-could be bidirectional in internal hyphae of AMF.This study was aimed at suppling previous exploratory result for strengtherning absorption effectiveness of Canna indica L.,especially for establishing targeted nitrogen removal function of AMF-canna symbotic system from the level of molecular biology.