Study On The Production Of Arginine By Legumes Inoculationed With Arbuscular Mycorrhical Fungus Under Different Conditions

There are a lot of arbuscular mycorrhical fungi and rhizobium existed in the rhizosphere ecosystem of Legume,they formed the sysbiosis of arbuscular mycorrhizal fungi,legumes and rhizobia in the long process of evolution.In the symbiotic system,the extraradical mycelium of AM fungus could absorbe the phosphorus from the external environment to supply legumes,and promote nodule formation and nitrogen fixation.On the contrary,the nitrogen fixation could provide good nitrogen nutrition for the growth AM fungi, enhance the root infection rate of AM fungi. AM fungi could also absorbe various forms of nitrogen from the surrounding, then the nitrogen were transported by the form of arginine in the hyphae.In the paper,Phaseolus radiatus L.was used as the host plant to inoculation with AM fungi (Glomus intraradices),rhizobium (CCBAUA.25072) or double inoculation(AM fungi and rhizobium) grown in three-part pot culture system, we studied the effect of different amount of phosphate fertilizer, different forms of nitrogen sources, different combinations of nitrogen and phosphorus concentrations and cadmium stress on the absorption of nutrients and arginine production of nitrogen metabolism in the symbiotic system.(1)In order to study the effects of different amount of rock phosphate on the absorption of phosphorus and the production of arginine in the nitrogen metabolism of symbiotic system,we added different rock phosphate concentration as0g/kg,0.06g/kg,0.12g/kg, and0.24g/kg in the mycelium room of three-part pot culture system.The result showed that the effects of inoculated with both microorganisms were significantly higher compared with the inoculated with arbuscular mycorrhizal fungi,rhizobium.In the0.12g/kg levels,the total phosphorus content was the most,the number and fresh weight of root nodules in Phaseolus radiatus L was the maximum, the infection rate of AM fungi was the highest and the Arg contents were also in a high level,but as the increase of rock phosphate concentration, the effect reduced.(2)Rhizobium could absorb nitrogen from the air through the biological nitrogen fixation,AM fungi could use ERM absorb different forms of nitrogen from the external environment.In this part,different exogenous nitrogen:4mmol/L NH4Cl,4mmol/L NH4NO3,4mmol/L Urea and4mmol/LArg was added respectively in the mycelium room of three-part pot culture system to study the assimilation of different nitrogen and production of arginine generated by arbuscular mycorrhizal fungi in leguminous plants. The result showed that the effects of different nitrogen uptake and incorporation into arginine were different in3levels of inoculation.When Arg and Urea was the exogenous nitrogen in inoculation with AM fungi and double inoculation,the arginine concentration in the mycorrhizal roots was relatively high,and the double inoculation was significantly higher than single AM inoculation.But the change of arginine concentration was not obvious in rhizobium inoculation.In the double incolation,the mycorrhizal infection,chlorophyll content, mumber and weight of nodule,total uptake of nitrogen was significantly increased compared with AM fungi inoculation,and NH4NO3as the exogenous nitrogen was the highest.So the double incolation was more conducive to the absorption of nitrogen and the growth of plants.(3)Different concentrations of nitrogen and phosphorus was added in the mycelium room of three-part pot culture system to explore the best concentrations of nitrogen and phosphorus that beneficial for growth and generation.of arginine in the sysbiosis of arbuscular mycorrhizal fungi,legumes and rhizobia.The result showed that the biomass,the content of chlorophyll, the rate of root infection, nodule amount, the content of total phosphorus and total nitrogen and the level of Arg in the plant inoculated with both microorganisms were significantly higher than that single inoculated with arbuscular mycorrhizal fungi, rhizobium.They increased significantly with the increasing of nitrogen,while decreased with the increasing of phosphorus concentration,when in the4mmol/L Urea and0.01mmol/L KH2PO4level,the effect of plant was best. But the number and the fresh weight of nodule was decreased with the increasing of nitrogen concentration, increased with the increasing of phosphorus concentration,when in the0.4mmol/L Urea and0.1mmol/L KH2PO4level,the number and the weigh is the best.(4)In order to study the assimilation of different nitrogen and production of arginine in the sysbiosis of arbuscular mycorrhizal fungi,legumes and rhizobia under cadmium stress, different forms of exogenous nitrogen4mmol/L NH4NO3,(NH4)2SO4and Urea was added respectively in the mycelium room of the three-part pot culture system. The result showed that the growth of Phaseolus radiatus L was seriously affected by cadmium stress, but to some extent the addition of exogenous nitrogen could alleviate the stress of the plant inoculated with both microorganisms and arbuscular mycorrhizal fungi.And when the nitrogen concentration was same, the former was significantly better than the latter.In the cadmium stress, the rate of root infection of the plant inoculated with both microorganisms was highest in the NH4NO3fertilizer, the number and fresh weight of nodule was the most when used (NH4)2SO4fertilizer,and under Urea fertilizer the content of Arg was the highest. The activity of SOD, POD, CAT was significantly increased in cadmium stress,and with the adding of exogenous nitrogen the activity was improved in plant inoculated with both microorganisms and arbuscular mycorrhizal fungi, but the effects of different nitrogen was different, the activity of enzyme was higher in the double inoculation.