2种石斛属植物和小叶石仙桃多糖的组织化学定位

为对不同年龄的铁皮石斛(Dendrobium candidum)、铜皮石斛(D.moniliforme)及石斛伪品-小叶石仙桃(Pholidota chinensis)不同器官中的多糖进行组织化学定位,选择具有较高药用价值的石斛类药用植物和药用部位,确定铁皮石斛的最佳采收期,根据多糖的理化性质,材料经冰冻切片,用改良的高碘酸-席夫试剂(PAS)对多糖进行组织化学定位;结果表明,多糖类物质主要存在茎的薄壁细胞、根的皮层细胞、叶的叶肉细胞中。其总多糖含量有如下顺序:二年生的铁皮石斛茎>铜皮石斛茎≈>小叶石仙桃茎,铁皮石斛根≈铜皮石斛根>小叶石仙桃根,铁皮石斛叶≈小叶石仙桃叶>铜皮石斛叶。另外,在不同的器官中,铜皮石斛的多糖含量呈现“茎≈根>叶”和小叶石仙桃的多糖含量呈现“叶>茎≈>根”的规律,而二年生的铁皮石斛则为“茎>叶>根”。这表明在种间及同种植物的不同器官、不同年龄,其多糖的含量存在差异。而3种兰科植物中,以二年生铁皮石斛茎的多糖含量最高,表明其药用价值也最高。

Histochemical Localization of Polysaccharide in Two Species of Genus Dendrobium and Pholidota chinnesis Lindl

Using improved periodate-schiff reagent(PAS) and frozen segment methods to locate the polysaccharide in the root,stem and leaf of three species in Orchidaceae.The results showed that color reaction and special crystal deposition sites indicated that the parenchyma in stem,cortex in root and mesophyll in leaf were the main accumulation sites for polysaccharide;content of polysaccharide in two-year old D.candidum stem was higher than than that of D.moniliforme stem,which equal to or higher than that of P.chinensis stem,and the content of polysaccharide in D.candidum root was equal to that of D.moniliforme root,and they were higher than that of P.chinensis root.But in the leaf,the content of polysaccharide in D.candidum was equal to that of P.chinensis,but they were higher than that of D.moniliforme.And in different organs of three species,the content of polysaccharide in stem of D.moniliforme was almost equal to that of root,which general higher than that of leaf;and the content of polysaccharide in leaf of P.chinensis was higher than that of stem,which general equal to that of root or higher than that of root.But the content of polysaccharide in stem of two year-old D.candidum was general higher that of leaf,which higher than that of root.The results indicated that contents of polysaccharide were obviously different among the three different species,different organs of the same species or different year-old of plants,respectively;the highest polysaccharide content was in the stem of two year-old D.candidum.