无核荔枝胚胎异常发育的研究

STUDIES ON ABNORMAL DEVELOPMENT OF EMBRYO IN NUCLEAR FREE LITCHI

无核荔枝是荔枝中较为珍贵的品种，有丰富的假种皮，种子多退化，属焦核品系。在胚胎发育过程中，小孢子四分体形成后，虽然出现有些小孢子形状不规则，原生质少或无等现象，但也有发育正常的花粉粒。而大孢子在各个发育阶段均会出现各种败育现象，因此无法形成胚，这是产生焦核的主要原因。淀粉粒的积累和分布对胚囊和雄配子体的发育起着重要作用，其分布具有一个动态的变化途径，这与挂绿荔枝有相同之处。

The nuclear free Litchi is a more valuable variety in Litchis. It has rich spurious seed coat, more of the seeds have degenerated, so it belongs to the small putamen type. In the course of the embryonic development, after the microspore tetrad is formed, although some forms of the microspore were under developed, and lose of protoplasm, but some have formed normal microspore. Yet the megaspores have all kind of degenerated forms in all developmental phases, so it can't form the embryo, this is the main reason of forming small putamen type. Starch accumulation and dispersion are in possession of the important function to the development of embryo sac and male gametophyte. On the other hand, the dynamic characteristic of starch in nuclear free Litchi is similar to handing green Litchi.