栽培太子参块根的发育解剖学研究

应用石蜡制片技术研究了栽培太子参纺锤状块根的发育过程。结果表明,栽培太子参的块根是由其不定根发育而成。太子参不定根的初生结构与次生结构的发育可分为4个阶段:原分生组织阶段、初生分生组织阶段、初生结构与次生结构阶段,类似一般草本双子叶植物根的发育。其特点是初生结构的皮层细胞大,仅3 ~4层,内皮层细胞具凯氏带;初生木质部多为三原型,少数为二原型、四原型与五原型。次生结构中次生木质部约占根面积80 %,主要为薄壁组织细胞,导管呈稀疏的放射状分布其中。由不定根发育成块根过程中,根据从根头至根尾不同距离的各组成部分的面积及细胞层数分析,从上向下其维管形成层活动强度不同,从而根的直径大小不同,使根发育成上粗下细的纺锤状肉质块根。高碘酸-Schiff反应显示,在成熟的块根中次生韧皮部的薄壁组织细胞和次生木质部射线间的木薄壁组织细胞内富含淀粉粒,在有些木薄壁组织细胞中还含有草酸钙簇晶。

Development Anatomy on the Root Tuber of Cultivated Pseudostellaria heterophylla

The developmental process of the spindle-shaped root tuber of Pseudostellaria heterophylla was studied by paraffin sectioning.It was shown that the root tuber of cultivated P.heterophylla was originated from adventitious root.The development of P.heterophylla adventitious root included four developmental stages,promeristem,primary meristem,primary structure and secondary structure stages,and was similar to that of other herbaceous dicotyledons.The cortex cells of primary structure were 3~4 layers,which volume was large.The endodermis had clear casparian strips.Primary xylem was triarch in most cases,and it was diarch,tetrarch and pentrarch in less cases.80% of secondary structure areas were formed by secondary xylem which composited by parenchyma cells mostly.The vessel scatteredly distributed among the parenchyma cells.It was shown that the different activities of vascular cambium from top to tail of the root led the different diameters of it,so that the root became the spindle-shaped root tuber.The area and cell layers of different parts from top to tail of roots were statistical analyzed.In the experiment of periodic acid-Schiff reaction,the starch grains were stored in the parenchyma cells of the secondary phloem and between the vascular rays of secondary xylem.The clustered crystal of calcium oxalate was also observed in the parenchyma cells in the secondary xylem.