黑松花粉体外萌发与花粉管生长的研究

应用荧光标记和激光扫描共聚焦显微镜术研究了黑松花粉和花粉管的形态结构,结果表明:黑松成熟花粉含2个退化的原叶细胞、1个生殖细胞和1个管细胞;花粉水合12 h后才开始萌发,花粉萌发后管细胞核移动进入花粉管内,而生殖细胞仍留在花粉粒内;伸长的花粉管可分淀粉粒区和透明区;花粉管内原生质的流动呈喷泉式;花粉管壁具纤维素层;年青的花粉管壁有胼胝质沉积,而较老的花粉管壁不具胼胝质层,花粉管内亦不具胼胝质塞;花粉管易于形成分枝,培养基中蔗糖浓度与分枝的形成有关;培养基中高浓度蔗糖可抑制花粉管的伸长.裸子植物在花粉结构、花粉萌发和花粉管的形态结构方面与被子植物存在较大差异.

In V itro Pollen Germ ina tion and Pollen Tube Growth of P inus thunbe rgii

The organization of pollen and pollen tubes of Pinus thunbergii was studied by using a confocal laser scanning microscope after thallial cells, one gen fluorescence labeling. A Pinus thunbergii pollen was 4-celled pollen with two degenerated proerative cell and one tube cell. In culture, pollen germination occurred after approximately 12 h of hydration. During tube growth, the tube cell nucleus moved into the elongating tube, but the generative cells remained within the pollen grain. There are two distinct zones in elongating pollen tubes. One began in the pollen and extended towards the pollen tube tip, containing abounding amyloplasts. The other zone was the clear zone lacking amyloplasts at the elongating pollen tube tip. The cytoplasmic-streaming type in the tube cell was a regular fountainlike pattern, with organelles moving towards the tip in the center of the tube and away from the tip along the cell cortex. Fluorescence microscopy indicated that the pollen tube wall contained cellulose microfibrils and, callose was present in the younger pollen tubes, but disappeared from the older tubes. No callose plug was detected within the pollen tube. The pollen tube generally developed two to six branches. The sucrose concentration in culture medium affected the formation of tube branching and the growth rate of tubes to a great extent. The present study suggested that the development and cellular organization of gymnosperms pollen tubes were considerably different from those of angiosperm pollen tubes.