风信子再生胚珠的大孢子发生和胚囊发育的细胞学观察

CYTOLOGICAL OBSERVATION ON MEGASPOROGENESIS AND EMBRYO SAC DEVELOPMENT OF REGENERATED OVULE IN HYACINTH

离体条件下风信子(Hyacinthus orientalis L.)再生胚珠的形态发生及大孢子发生和胚囊发育的细胞学研究表明:再生胚珠具有正常的珠被、珠心和珠柄的分化过程,但其形状与自然情况下的明显不同,绝大部分再生胚珠是直生型和半倒生型,与自然情况下相同的倒生型胚珠极少;胚珠的大孢子发生和胚囊的发育具有正常的细胞学过程。最后可形成1个卵细胞,2个助细胞,1个中央细胞和3个反足细胞的8核蓼型胚囊。结果表明,处于完全孤立状态下的再生胚珠,自分化启动以后即能按预先确定的发育程序完成大孢子发生和胚囊发育的复杂过程。由此推测,完成这个复杂过程是胚珠自控的,它不需要来自花芽或植株的任何信息。

The morphogenesis of regenerated ovule and cytological changes of its megasporogenesis and embryo sac development were studied. Results showed as follows: 1. the differentiation of the regenerated ovule had followed a normal process in the order of inner integument touter integument and then funiculus. But the form of the regenerated ovules in vitro was quite different from that of ovule in vivo. Most of the regenerated ovules were orthotropous and hemianatropous, only a few were anatropous which are the same with that in vivo. 2. the megasporogenesis and the embryo sac development also had normal cytological process, and the Polygonum type-embryo sac consisted of one egg, two synergids, one central cell and three antipodals could be seen in mature regenerated ovule. These ex-perimental results make clear that the regenerated ovule differentiated directly from explant could accomplish the complex processes of megasporogenesis and embryo sac development. By this fact, authors infer that once the differentiation of ovule primordium,the complex biochemical programs for the megasorogenesis and embryo sac development can be controlled by the ovule itself and need no more information from flower bud and /or plant.