盾叶薯蓣根状茎的发育解剖学和组织化学研究

Studies on the Developmental Anatomy of Rhizome of Dioscorea zingiberensis and Its Histochemistry

盾叶薯蓣根状茎顶端的生长点由鳞片包被,其衍生细胞分化为原表皮、基本分生组织和散生的原形成层束,以后分化为表皮、基本组织和散生的维管束构成的初生结构。根状茎顶端下方的原表皮内存在初生增厚分生组织,其细胞不断向内分裂和其衍生细胞的体积增大使根状茎能够迅速增粗。分化完成的根状茎主要由周皮、基本组织和散生的维管束构成。周皮由木栓层、木栓形成层和栓内层组成;基本组织由薄壁细胞组成;维管束属于有限维管束。薯蓣皂甙主要存在于基本组织薄壁细胞中。原分生组织和原形成层不含薯蓣皂甙,维管束的木质部和韧皮部中的韧皮纤维也无薯蓣皂甙的分布,韧皮部的生活细胞和维管束鞘细胞有薯蓣皂甙的积累。近顶端的基本分生组织细胞内薯蓣皂甙不形成液滴,随着细胞分裂逐渐停止,细胞内开始形成含薯蓣皂甙的液滴,反映皂甙是在成熟细胞内积累。其中,有小型维管束分布的基本组织中薯蓣皂甙的积累与分布最丰富,两年生根状茎中薯蓣皂甙的含量比一年生的高。

The tip of rhizome of Dioscorea zingiberensis C.H.Wright is surrounded by lepises.The cells derived from primordial meristem forms protoderm,ground meristem and dispersed procambium strands.The primary structure of the rhizome is includes epidermis,ground tissue and dispersed vascular bundles.There is primary thickening meristem at the lower part of rhizome tip under protoderm.The increase of cell number derived from primary thickening meristem and the enlargement of cells volume make the rhizome thicken rapidly.The mature rhizome is composed of periderm,ground tissue and vascular bundles.The periderm consists of phellem,phellogen and phelloderm;the ground tissue is of parenchyma;vascular bundle belongs to closed vascular bundle.Dioscin exists mainly in parenchyma cells of ground tissue.The primordial meristem and the procambium strand do not contain dioscin and the xylem and the phloem fiber of the vascular bundle do not contain dioscin either,but the life cells of phloem and the cells of vascular bundle sheath accumulate dioscin.Dioscin does not exist in the form of granule in ground meristem near the tip of rhizome,but granulous dioscin is formed in the cells of mature ground tissue.Dioscin that accumulated and distributed in ground tissue with small vascular bundle is the most abundant in the rhizome.The amount of dioscin of biennial is higher than that of annual rhizome.