盾叶薯蓣实生苗根状茎的形态发生及薯蓣皂甙积累的研究

Studits on the morphogenesis of rhizome from seedling and the accumulation of dioscin of Dioscorea zingiberensis

对盾叶薯蓣实生苗根状茎的形态发生、发育过程及薯蓣皂甙积累与分布进行了研究 .种子萌动后 ,节部膨大形成球状体 ,其直径约 1 .5 cm.其胚芽生长锥先后形成 4个突起 ,分别发育形成芽的原分生组织 .按其出现的先后分别称为第 1芽、第 2芽、第 3芽和第 4芽 .第 1芽呈剑指形 ,以后发育为地上缠绕茎 ,其余 3个芽呈丘状突起都分别发育为地下根状茎 .有的芽的原分生组织以后还可以形成 2个芽的原分生组织 ,从而使根状茎形成分枝 .根状茎顶端的原分生组织由鳞片包被 ,顶端下方的原表皮内存在初生增厚分生组织 .初生增厚分生组织细胞不断向内分裂和其衍生细胞的体积增大 ,是根状茎能迅速增粗的主要原因 .分化完成的根状茎由周皮、基本组织和散生的维管束构成 .经组织化学测定 ,根状茎中薯蓣皂甙主要存在于基本组织的薄壁细胞中 ,呈液滴状 .原分生组织不含薯蓣皂甙 ,近顶端的基本分生组织细胞内不形成含薯蓣皂甙的液滴 .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 。

Studies on the morphogenesis and development of rhizome from seedling and the accumulation of dioscin of Dioscorea zingiberensis C. H. Wright have been made in this article. After germination, the knot expands into spheroid whose diameter is about 1.5cm. The apical cone of embryo bud gives rise to 4 tubercles early or late, which develop into primordial meristems of buds respectively. The first bud develops into twining stem, and the others develop into rhizomes. Some of the primordial meristems form two buds, this leads the rhizome to form branches. The primordial meristem at the tip of rhizome is surrounded by lepises. There is primary thickening meristem at the lower part of rhizome tip under protoderm. The increase in cells number derived from primary thickening meristem and in cells volume make the rhizome thicken rapidly. Full developed rhizome is composed of periderm, ground tissue and vascular bundle.After histochemistry determination, it shows that dioscin take the form of liquid drop and exists mainly in the cells of parenchyma 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 take the form of liquid drop in ground meristem near the tip of rhizome, but liquid drop that contain dioscin is formed in the cells of ground tissue along with the cease of cell division. 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.