穴居植物湖南报春苣苔大小孢子发生及雌雄配子体发育研究

Sporogenesis and Gametogenesis of Cave-dwelling Plant Primulina hunanensis

目的:湖南报春苣苔(Primulina hunanensis)为我国特有的极具观赏价值的岩溶洞穴野生植物,具耐荫、耐贫瘠等特性,但其自然分布范围狭窄、野生种群规模小。胚胎发育是植物生活史中的关键环节,研究湖南报春苣苔的胚胎发育特征,为苦苣苔科(Gesneriaceae)植物的栽培育种提供新思路。方法:以湖南报春苣苔为材料,运用经典石蜡切片技术,对大、小孢子发生及雌、雄配子体发育过程进行解剖学观察。结果:湖南报春苣苔花药4室,花药壁由外到内依次为表皮、药室内壁、中层和腺质型绒毡层;小孢子母细胞减数分裂时的胞质分裂为同时型,四分体偶为交叉(十字)形,多为四面体形,花粉为二细胞型;倒生胚珠,单珠被,薄珠心,胚囊发育方式为蓼型。湖南报春苣苔花粉粒发育不同步,存在花粉败育、雌雄配子体异熟现象。结论:研究为报春苣苔属(Primulina)植物积累了基础的胚胎学资料,对于揭示苦苣苔科植物生殖机制及改良植物繁殖育种方式具有重要意义。

Objective:Primulina hunanensis was a unique karst cave wild plant with great ornamental value in China.It had the characteristics of shade tolerance and barren tolerance,but its natural distribution range was narrow and the size of wild population was small.Embryonic development was a key link in the life history of plants.Studying the embryonic development of P.hunanensis would provide a new idea for the cultivation and breeding of plants in Gesneriaceae.Methods:Using P.hunanensis as the material,conventional paraffin sectioning technology was used to make anatomical observations on the megasporogenesis,microsporogenesis and the development of female and male gametophytes.Results:The anthers of P.hunanensis had four chambers,and the anther wall from outside to inside was sequentially composed of epidermis,endothecium,middle layer and glandular tapetum.The cytokinesis type was simultaneous type during meiosis of the microspore mother cell.A few tetrads were decussate type,most were tetrahedral type,and the pollen was two-celled type.The ovules were anatropous,single integument,tenuinucellate ovule,and the mode of development of the embryo sac was polygonum type.The pollen grain development of P.hunanensis was not synchronized,and there were phenomena of pollen abortion,male and female gametophyte heterogenesis.Conclusion:The study accumulated basic embryological data for plants of the genus Primulina,which was of great significance for revealing the reproductive mechanism of plants in Gesneriaceae and improving plant reproductive breeding methods.