滴水珠珠芽发育过程研究

摘要

Tuber of Pinellia cordata has been the extensively used as medicines in the practice of traditional Chinese medicine. Bulbil formation is the main propagation strategy of P. cordata in wild. There are two developmental stages of bulbils for each one individual: on the basis of leaf blade(upper bulbil)and on the lower part of petiole(lower bulbil). To reveal the developmental characteristics of bulbil formation in P. cordata,morphological and anatomical ob?servation were systematically used. Morphological observation showed that the whole development process of upper or lower bulbil could be divided three stages:no visible bulbil structure,primary bulbil formation under epidermis,growth and maturation of bulbil.Correspondingly,anatomical observation showed that the whole development process of upper or lower bulbil could be divided four stages:initial cell formation,bulbil promodia formation,differentiation of bulbil,and bulbil growth continuously to maturation. The initial cell of bulbil was derived or dedifferentiated from the parenchyma cell which was located in the adaxial side of young petiole.Initial cell formation was not visible.Continuously division of the initial parenchyma cell resulted in the formation of bulbil primodium,which was a group of undifferentiated cell.The primordium continuously growth and then differentiated to form the shoot apical meristem(SAM),which was the infant bulbil on the adaxial side. Bulbil promodium formation and early primodium differentiation could be visible with white dot structure on petiole.Subsequently,differentiated bulbil growth and lateral scale leaf differentiation continuously char?acterized the bulbil growth stage. Bulbil growth terminated with the leaf senescence. The average diameter of maturated upper bulbil on blade and lower bulbil on petiole were(2.79 ± 0.40)mm and(2.69 ± 0.36)mm, respectively. The maturated bulbils generally were gray and ellipsoidal,and shaped with various number of external scale leaf. The inner cells of maturated bulbil contained lots of nutrients(storage).The germination rate of bulbils was up to 75%in soil cul?ture. Morphological and anatomical observation results indicate that the development of bulbils in P.cordata is the same in P. ternata,and the development of bulbil in P. cordata is an effective reproduction strategy just like in P. ternata.%珠芽是滴水珠(Pinellia cordata)的营养繁殖结构,为揭示滴水珠珠芽发育过程中的特征,该研究以野外采集材料进行盆栽观察试验,通过形态观察法和石蜡切片方法,探索滴水珠叶片和叶柄处珠芽发育过程中的形态学和解剖学结构特征.结果表明:滴水珠珠芽发育过程在形态上分为叶柄无现象时期、早期珠芽结构分化和珠芽膨大成熟时期三个时期;相应的解剖学发育时期为珠芽原基启动期和形成期、原基分化期和膨大成熟期四个阶段.叶片和叶柄珠芽起始细胞均由叶柄腹面表皮下层薄壁细胞组织脱分化形成,起始细胞不断分裂形成细胞团最后发育成珠芽原基;在原基分化期的特征是生长点形成,最终分化形成芽原基和鳞片叶;膨大成熟期的特征是珠芽结构不断生长,生长点侧生分化鳞片叶增多.叶片和叶柄处珠芽成熟脱落时期为灰色椭圆形结构,测得平均直径分别为(2.79 ± 0.40)mm和(2.69 ± 0.36)mm,外部有鳞片包裹,内部含大量营养物质.在环境适宜条件下,珠芽遇土萌发,萌发率达75%.这表明滴水珠珠芽与同属植物半夏珠芽发育过程差别不大,都是无性克隆营养繁殖体结构.