牡丹苗端由营养生长转向生殖生长过程中超微结构研究

ULTRASTRUCTURAL STUDY OF SHOOT APEX IN PAEONIA SUFFRUTICOSA ANDR. FROM VEGETATIVE GROWTH TO REPRODUCTIVE GROWTH

电镜观察了营养生长和生殖生长两个发育时期的牡丹（PaeoniasuffuticosaAndr．）苗端。结果如下：（1）营养生长期，原套和原体的细胞壁厚薄不均，多有胞间连丝分布。两者细胞核内均有较多异染色质。细胞质内含许多质体、嗜铁细胞器及少量的线粒体、内质网和高尔基体。质体无片层结构，部分质体有淀粉粒和脂滴。原体细胞的液泡化程度比原套细胞略高。原体下方扁平细胞的大部分空间被大量的淀粉质体和液泡占据，淀粉粒边缘与细胞壁上附着许多电子密度透明物。（2）生殖生长期，外套、内体及内体下方的扁平细胞内嗜锇细胞器、脂滴和小液泡数目均增加。此外，外套细胞核内异染色质减少。内体细胞壁薄处，胞间连丝丰富，核内异染色质仍较多。扁平细胞内淀粉质体数量明显减少。

Shoot apexes of peony in vegetative growth and reproductive growth were observedwith electron microscope. (1) At the stage of vegetative growth, the thickness of cellwalls in both tunica and corpus is not uniform,and plasmodesmata are seen in most cellwalls. There are a lot of heterochromatin in their nuclei. Many plastids,osmiophilic or-ganelles and a few mitochrondria,endoplasmic reticulum and Golgi bodies are found inthe cytoplasm. The plastids lack lamellar structures,some of them contain starch grainsand lipid drops. The corpus cell is slightly more vacuolate than the tunica cell. Flat cellunder corpus is occupied mainly by rich starch-containing plastids and vacuoles. On theedges of starch grains and cell walls,a lot of transparent electron-density materials lie.(2) At the stage of reproductive growth, osmiophilic organelles, lipid drops and small vacuoles show an increased number in mantale cell,core cell and the flat cell under core.In addition,the heterochromatin decreases in the mantale nucleus. Abundant plasmodes-mata present in the position of thin walls of core cell which still has a lot of heterochro-matin. In the flat cell,the number of starch-containing plastids reduced sharply.