The Formation,Distribution And Remobilization Of Root Apoplastic Iron Pool

The mechanism that Controls the fomation and remobilization of root apoplastic iron pooi in dicotyledonous and gramineous Plants had been studied by Physoilogical and cytochemical methods, The main results are summ arized as follows: in order to study the role fern erductase in the remobilization of root apoplastic iron pool, We developed a new cytochemical method for the light and electron microscope demonstration of ferric reductase using soybean root as experimental material which was cultured under iron deficiency. The chemical basis of this method is that the reduction of ferricyanide by fernic reductase in the presence of cupric ions forms a brown-colored insoluble and electron-dense precipitate of cupric ferrocyanide at the site of enzyme activity. For the observation under light microscope, the dull brown precipitats was converted into sharp-contrasted black silver precipitate by the sulfide-silver amplification method. Our experimental result exhibited that the localization of ferric reductase obtained by this method was accurate and specific. Under electron microscope. the dense enzyme reaction product was found to cover the plasmalemma as fine granules. This is consistent with the results of other researchers obtained by biochemical method. The present method for the localization of ferric reeducates if more accurate than prussian blue staining method, because the brown precopitate in this method is finer than the Prussina blue pricipitate and the pH 6.6 of the reaction medium is closer to the optimum pH of 5.5-6.5 for ferric reductase than the pH 3 of the prussian blue staining solution,low pl-Imaybe harmful to plasmalemma.