牛膝根的结构发育与三萜皂苷积累的关系

应用植物解剖学、组织化学定位及植物化学技术,研究了不同发育时期牛膝根的结构特征与三帖皂苷积累的关系。结果表明:牛膝根的初生结构和次生结构类似于一般双子叶植物,其根的加粗主要是由于三生结构的发生和分化。第一圈额外形成层产生于次生韧皮部外侧的薄壁组织细胞和射线细胞,以后的每一圈由前一圈向外衍生的薄壁组织细胞产生。额外形成层无纺锤状原始细胞和射线原始细胞之分,在切向纵切面上呈叠生排列。三生维管束以离心方式排成整齐的同心环状,由薄壁结合组织将其彼此分开,其圈数与额外形成层的圈数是一致的,随着根的个体发育而不断增加。在根的初生结构中,三萜皂苷主要分布于中柱鞘、初生韧皮部及初生韧皮部和初生木质部之间的薄壁组织细胞内;在根的次生结构中,主要分布于次生韧皮部及栓内层的薄壁组织细胞内。当三生结构形成后,除次生韧皮部及栓内层细胞外,在额外形成层和三生维管束韧皮部细胞内均有皂苷类物质积累。三生结构在牛膝根中占主要地位,是三萜皂苷积累与分布的主要场所。在牛膝根的生长发育过程中,三萜皂苷元齐墩果酸的百分含量呈“S”型曲线增长,其根的增长、加粗、三生维管束圈数、三萜皂苷总量及根中干重的积累量都在出苗后约120天达到高峰,此时应为牛膝根的最佳采收期。

STRUCTURAL DEVELOPMENT OF ROOT AND THEIR RELATIONSHIP TO ACCUMULATION OF TRITERPENOID SAPONINS IN ACHYRANTHES BIDENTATA BL

A study concerning the relationship of dynamic accumulation of triterpenoid saponins and anatomical characteristics of Achyranthes bidentata Bl roots was undertaken by anatomical, histochemical and phytochemical method respectively. Results revealed that the primary and secondary structures of the root resembled those of usual dicots. The continual thickening growth of root principally resulted from the differentiation and development of the tertiary structure. The first ring of supernumerary cambium originated from the parenchyma and vascular ray cells of secondary phloem and each of the followed rings initiated in the outmost foundamental parenchyma cells which were derived from the immediate preceding ring. In the supernumerary cambiums, there had not distinction between the fusiform initial and the ray initial. Its cells present stratifide arranged from a longitudinal section through root. Regular and concentric rings of tertiary vascular bundles who differentiate centrifugally were enclosed by the connective parenchyma. The number of the rings continually increase with the development of the root itself. Triterpenoid saponins accumulated mainly in pericycle, primary phloem and parenchyma between primary phloem and xylem in the primary structure of root but came into existence in cells of secondary phloem and phelloderm with secondary structure development of root, and as well as in supernumerary cambium and phloem of tertiary vascular bundle after the tertiary structure maturated gradually in the roots. The investigation provides indications that the tertiary structure were not only main parts in the roots of Achyranthes bidentata Bl, but also important storage region of triterpenoid saponins in its growth and development. In addition, the analysis of using the HPLC showed that dynamic increasing trend oleanolic acid was as "S" curve during the roots growth and development and up to the highest content of triterpenoid saponins after plants grew 120 days. Meanwhile, the number of the rings of tertiary vascular bundles, length and diameter of the roots were the same as the triterpenoid saponins increasing trend. It should be optimal season for harvest.