黄檗（芸香科）的珠孔塞和珠孔的形态发育及花粉管在子房室中的生长路径

利用扫描电子显微镜术和光学显微镜术研究了黄檗(Phellodendron　amurense　Rupr.)的珠孔塞和珠孔的形态发育和花粉管在雌蕊中的路径。黄檗胚珠的珠孔塞起源于珠柄。随着胚珠生长,珠孔塞逐渐增大,胚珠成熟时珠孔塞变得相当大并紧密地覆盖在珠孔上。当雌花进入可传粉期时,珠孔塞的形态发生很大变化,其表面细胞径向延伸,形成柱形、半乳突或乳突细胞。受精后,珠孔塞体积变小并逐步退化。花粉管在子房室中并非一定经过珠孔塞结构。花粉管是否经过珠孔塞取决于它们进入子房室的位置。我们不支持先前研究者关于珠孔塞主要充当对花粉管生长的机械作用的观点。我们对黄檗胚珠的珠孔的形态发育研究显示,在不同的生殖时期,珠孔的结构会发生变化,在传粉时期它的结构显示不对称性。黄檗珠孔塞和珠孔的发育与雌配子体发育存在密切关系。

Developmental Morphology of Obturator and Micropyle and Pathway of Poll Tube Growth in Ovary in Phellodendron amurense (Rutaceae)

The developmental morphology of the obturator and micropyle and the pathway of the pollen tubes in the ovarian locule in Phellodendron amurense Rupr. have been investigated by scanning electron microscopy and light microscopy. The obturator of the ovule is of funicular origin. As the ovule is fully developed, the obturator becomes considerably large and closely covers the micropyle. When the pistillate flower reaches the receptive phase, the morphology of the obturator is greatly modified, and its cells on the surface are radially expanded and appear to be columnar, semi-papillar orpapillar. Following fertilization the obturator reduces in size and degenerates. The pollen tubes need not necessarily traverse the obturator. Whether the pollen tubes pass the obturator or not depends on the sites at which they enter the ovarian locule. This observation does not support the idea that the obturator mainly serves the function of mechanical guidance for the growth of pollen tubes. Our investigations indicate that the structure of the micropyle changes with the different stages of the reproductive process, and becomes asymmetrical during pollination. The development of the obturator and the micropyle correlates with that of the female gametophyte in P. amurense.