水稻胚胎发生与萌发早期分离胚中内源激素的变化

以酶联免疫吸附检测技术分析了水稻(Oryza sativa ssp．iapoica)分离胚不同发育时期及萌发早期的内源激素含量的动态变化。GA1含量是所测激素中含量最高的。GA1的变化趋势基本上与ABA相反。花后4d的胚中GAl和ABA的含量最高；花后8d到18d，GA1的含量下降，而ABA含量增加。在早期萌发过程中，种子吸涨后2d的胚中GA，含量迅速上升，而ABA下降。GA1／ABA的最高比值也出现在吸涨后2d的胚中。iPAs和ZRs的最高含量也出现在开花后4d的胚中，但随后含量均下降到相当低的水平，并几乎没有变化。研究结果进一步证实了GAl在早期胚胎发生和萌发过程中起重要的作用；推测iPAs和ZRs可能仅在胚胎发生的早期起作用；GA1与ABA含量之间的相对平衡控制着胚胎发育的过程。用分离胚作为测试材料可以避免胚乳等其他组织成分的干扰，从而比较准确地反映了胚的内源激素变化。此外，本研究是首次用4d的水稻幼胚作为激素含量测定的起始材料。

Fluctuations of Endogenous Hormones in Isolated Rice Embryos During Embryogenesis and Early Stages of Germination

Fluctuations of levels of several endogenous plant hormones in isolated rice ( Oryza sativa ssp. japonica ) embryos during early and mid_embryogenesis and early stages of germination were studied by enzyme_linked immunosorbent assay (ELISA). Embryos were collected at different days after pollination (DAP) and different days after imbibition (DAI) of mature seeds. The contents of gibberellin 1 (GA 1), abscisic acid (ABA), isopentenyladenine and isopentenyladenosine (iPAs), zeatin and zeatin riboside (ZRs) were immunochemically assayed. The GA 1 level was the highest among all hormones tested. The variations of GA 1 levels were opposite with the ABA levels, with some exceptions. During early and mid_embryogenesis, the levels of GA 1 and ABA were the highest at 4 DAP. From 8 to 18 DAP, GA 1 level declined, whereas the ABA level increased. During germination, GA 1 level increased at 2 DAI whereas simultaneously the ABA content decreased. The highest ratio of GA 1/ABA was observed at 2 DAI. The levels of iPAs and ZRs were maxima in the embryos at 4 DAP, decreased to a very low level and maintained constant thereafter. Our results provide further evidence that GA 1 plays an important role in the early stages of embryo development and germination. The balance between GA 1 and ABA, rather than their absolute contents, controls these processes throughout the development, whereas iPAs and ZRs may play important roles in early embryogenesis. The use of isolated embryos as starting material avoids the usual interferences with other tissues such as the endosperm. In addition, this is the first report dealing with the hormonal balance of early_embryos in rice.