首页 > 分享 > 珍稀濒危植物十齿花属的花药发育和雄配子体发生及其系统学意义

珍稀濒危植物十齿花属的花药发育和雄配子体发生及其系统学意义

花匠小妙招
2024-11-04 00:22

摘要： 十齿花属（Dipentodon）为东亚特有单型属，是国家二级保护植物，其系统位置长期有争议。本研究连续三年的野外观察结果表明十齿花（Dipentodon sinicus）的结籽率较低（4.31%）。同时利用常规石蜡制片技术，观察了十齿花的花药发育和雄配子体发育过程。十齿花的花药四室，花药壁发育类型为基本型。成熟花药壁有6层，由表皮，药室内壁，2层中层和2层绒毡层组成，绒毡层为腺质绒毡层。花药成熟时，纤维状加厚发生于药室内壁，便于花药开裂散粉。小孢子母细胞减数分裂的孢质分裂方式为同时型，小孢子四分体多为四面体型，稀左右对称型。成熟花粉粒为二细胞型，具3孔沟。在小孢子发育的减数分裂、小孢子四分体和二细胞型花粉时期，观察到发育不正常的现象，分别占40%、48%和36%。通过与其他亲缘类群的胚胎学特征比较，支持最新分子系统学把它独立成科，放在十齿花目的观点。雄配子体发育过程中，十齿花存在着花粉败育现象，这可能是导致其结实率低的原因之一。

关键词: 花药发育, 十齿花属, 小孢子发生, 系统学, 珍稀濒危物种

Abstract: The monotypic genus Dipentodon Dunn is endemic to Eastern Asia and has been rare and endangered due to the habitat loss. Its systematic position has been controversial. The investigation in a natural population showed that the average ratio of seed-setting in D.sinicus was very low with a number of 4.31% for three successive years. The anther development and microsporogenesis of D.sinicus were observed by means of conventional paraffin sections. The anther is tetrasporangiate, and its anther wall comprises four or five layers:an epidermis, an endothecium, one or two middle layers and a tapetum. The development of anther wall belongs to basic type. The tapetum is glandular type, and wall thickening occurs in endothecium. Cytokinesis of microsporocyte meiotic division is simultaneous, and the tetrads are tetrachedral, occasionally isobilateral. The mature pollen grains are two-celled with three colpates. The high percentage of pollen abortion was observed in process of male gametogenesis. Comparative embryological features supported the molecular view that Dipentodon should be included into Dipentodentaceae among order Huerteales. The abnormality in the pollen development in Dipentodon might be one of the main causes resulting to its extremely low seed-setting.

Key words: anther development, Dipentodon, microsporogenesis, systematics, rare and endangered species

中图分类号:

Q944.58