【作者】 史维宁；

【导师】 贾恢先； 张福锁；

【作者基本信息】 甘肃农业大学 ， 作物栽培学与耕作学， 2000， 硕士

【摘要】 采用生理学与细胞化学实验技术，研究了双子叶植物和禾本科植物根系植外体铁库的积累与活化吸收机制。 1．细胞化学方法和X-射线显微能谱分析结果证明，禾本科植物质外体铁主要位于根表粘液层中，它属于根表或根际的范畴，而非严格意义上的质外体。双子叶植物质外体铁主要位于根系1-3层表皮细胞壁中，另外在根和叶的韧次部细胞壁中也有分布。 2．对细胞壁中负电荷的分布及其相对密度进行原位测定显示，双子叶植物根尖表皮细胞壁和成熟根及叶片的韧皮部细胞壁中具有较高的负电荷密度，而禾本科植物根表的负电荷密度很低。 3．对分离纯化的细胞壁进行分析发现，禾本科植物细胞壁中含有较多的酚类化合物，它主要决定质外体中铁的积累；而双子叶植物细胞壁中酚类化合物含量较低，其中质外体铁的积累，主要由果胶质的负电荷决定。更多还原

【Abstract】 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.更多还原