Effect Of Different Nitrogen And Phosphorus Sources On Arginine Formation And N Transfer In A Fungus And Cotton (Gossypium Hirsutum L) Symbiosis

The extraradical mycelium （ERM） of AM fungus was able to take up and assimilate various forms of nitrogen from the surroundings. During nitrogen and phosphorus uptake and assimilation, most of the nitrogen will be incorporated into Arg （Arg） and PolyP, ERM was taking up fixed carbons as hexose from the apoplast of the host root cortex. The N and P was very important to growth for plant because of their removable, so our experiment was aim to research different N and P affect the ERM uptake this two nutrients and transfer to plants.We design six contentrations of nitrogen and phosphorus, and use Rhizophagus irregularis to infect cotton. The results show that the high concentration of nitrogen is benefit to cotton inoculated with R. irregularis, especially the 100mmol·1^-1; 0.025mmol·1^-1 concentration of phosphorus is conducive to hypha of R. irregularis to infect the root of cotton. To investigate the effect of different nitrogen on Arg formation and N transfer in a R. irregularis-cotton symbiosis. We use the fungal compartment which consist of a root compartment （RC）, hyphal compartment （HC） and a buffer chamber to research the root colonization, biomass of R. irregularis and cotton, the content of Arg in ERM and mycorrhizal root, as well as the total nitrogen of shoots and leaves to add 2 ml five nitrogen sources which are Arg, glutamine, urea, KNO₃ and NH₄Cl under the concentration which is 5 mmol/l,50 mmol/l,500 mmol/l into HC. This result show that root colonization is more higher than 90% when we apply 5 mM Arg, Gln and urea into HC; when we use 50 mM NH₄Cl, the dry weight of ERM is 270.17 mg, There is significant different on Arg content, especially add Arg into HC, the significant influence to ERM dry weights are NH₄Cl and Gln. The cotton height is 20.14 cm and shoots dry weights are 0.88 g by added Arg; when ERM uptake urea, the content of Arg in ERM is 11.9961 mg/g; but the Arg content in root colonization is 24.3952 mg/g and the total nitrogen in leaves is higher by assimilated Gln. In addition, we use 500 mM urea into HC, the root colonization is 89%, there is significant different effect on the content of Arg in ERM and mycorrhizal root, and total nitrogen of shoots and leaves.The capacity of assimilate exogenous phosphorus by AM fungus are different in RC. Add different phosphorus in RC to research ERM in which growth in HC to uptake capacity of. nitrogen. The result show that only lower KH₂PO₄. Ca-perphosphate and phosphate rock all infect root of cotton and then develop ERM. So we detect the content of P in ERM and roots in RC, ignore the N content in HC. The P content in ERM is small when use the higher exogenous P in RC, but roots is rever. This result involve in direct and indirect uptake in extraradical mycelium.Arg biosynthesized in the ERM through the anabolic arm of the urea cycle was possibly transported with polyphosphate （PolyP） along the motile tubular vacuole to the IRM. The aim of this research is to study the effects of different forms of external phosphorus on the assimilation of nitrogen and production of Arg by AM fungus. The results showed that exogenous phosphorus can limit the gowth of AM fungus, but improve the development of cotton. Besides, the content of Arg in mycorrhizal roots is much higher when add phosphate rock into HC; The total nitrogen and phosphorus content in leaves is higher than shoots, but the nitrogen in shoot is the hightest, but the total phosphorus content is the lowest by used phosphate rock. This indicated that phosphate rock can promote the N transferation. There is significant different on nitrogen and phosphate content under the same nitrogen.