七筋姑的大小孢子发生雌雄配子体发育及多糖物质的动态

MEGA-MICROSPOROGENESIS AND MEGA-MICROGAMETOGENESIS AND CHANGES IN POLYSACCHARIDES IN CLINTONIA UDENSIS

七筋姑(Clintonia udensis Trautv. et Mey)具倒生胚珠、双珠被、薄珠心、单个孢原。大孢子母细胞减数分裂后形成1+3排列,合点端三核退化,珠孔端有功能的大孢子核进行两次有丝分裂。成熟胚囊具5核或6核,即1组卵器、1上极核、合点端的1个或2个退化核。胚囊发育为四孢子、高度退化的贝母型。花药壁由表皮、药室内壁、两层中间层及绒毡层组成,发育属单子叶型。绒毡层解体方式为分泌型。小孢子母细胞减数分裂时胞质分裂为连续型。二轴对称式四分体,2-细胞成熟花粉粒。组织化学表明:大小孢子发生及雌雄配子体形成过程中的不溶性多糖颗粒的分布呈现规律性变化。

In Clintonia udensis Trautv. et Mey, the ovule is of anatropous type, having two integuments. The nucellus is tenuinucellate with unicellular archesporium derived from the hypodermal cell at the tip of the young nucellus acting directly as the megaspore mother cell. The division of the megaspore mother cell results in 1+3 arrangement, the three nuclei in the chalazal end degenerate and fuse in various ways. The nucleus of the functional micropylar megaspore divides twice. The mature embryo sac contains 5 or 6 nuclei, including 1 egg, 2 synergids, 1 polar nucleus and 1 or 2 abortive nuclei at the chalazal end. The pattern of the embryo sac development belongs to the tetrosporic highly reduced Fritillaria type. The anther wall consists of the epidermis, the endothecium, two middle layers and the glandalar tapetum. The cytokinesis is successive and the tetrad isobilateral. Mature pollen grains are two celled. Histochemical investigation includes the localization of polysaccharides during the mega-microsporogenesis and the mega-microgametogenesis. The accumulation of polysaccharides shows some regular changes.