白鲜根的发育解剖学研究

应用半薄切片、常规石蜡切片并结合离析法,对药用植物白鲜(Dictamnus dasycarpus Turcz.)根的发生发育过程进行了研究。结果表明:白鲜根的发生发育过程包括4个阶段,即原分生组织阶段、初生分生组织阶段、初生结构阶段以及次生结构阶段。原分生组织位于根冠内侧及初生分生组织之间,衍生细胞分化为初生分生组织。初生分生组织由原表皮、基本分生组织以及中柱原组成。原表皮分化为表皮,基本分生组织分化为皮层,中柱原分化为维管柱,共同组成根的初生结构;在初生结构中,部分表皮细胞外壁向外延伸形成根毛,皮层中分布有油细胞,内皮层有凯氏带,初生木质部为二原型或偶见三原型,外始式;根初生结构有髓或无。次生结构来源于原形成层起源的维管形成层的活动以及中柱鞘起源的木栓形成层的活动;白鲜次生韧皮部宽广,其中多年生根中可占根横切面积的85%,另外除基本组成分子外,还分布有油细胞;周皮发达,木栓层厚;初生皮层、次生木质部和次生韧皮部薄壁细胞中常充满丰富的淀粉粒。

Developmental Anatomy of Dictamnus dasycarpus Roots

The developmental anatomy of Dictamnus dasycarpus Turcz.roots was studied,using semi-sectioning,paraffin sectioning and maceration.The results show that the development of D.dasycarpus roots is characterized by four developmental stages,including promeristem stage,primary meristem stage,primary structure stage and secondary structure stage.The promeristem locates between the root cap and primary meristem,and clusters of cells from promeristem develop into the primary meristem which consists of protoepidermis,ground meristem and plerome.The protoepidermis develops into epidermal cells,the ground meristem differentiates into cortex,and the plerome develops into stele.The primary structure consists of epidermis,cortex and stele.And the outer cell walls of some epidermal cells develop into root hairs through outward growth.The oil cells and the casparian strip are also detected in cortex and endodermis,respectively.The primary xylem which is diarch or infrequent triarch is exarch.The center of the primary root is characterized by pith or not.The secondary structures derive from vascular cambium and cork cambium which differentiated from the cells in procambium and pericycle respectively.The secondary phloem is broad and contains 85% percentage of the root transverse section,the oil cells are also detected in the secondary phloem.The periderm is obviously thick.And abundant starch grains are existed in cortex and parenchyma cells of secondary xylem and phloem.