毛竹花粉的形态及双受精过程研究

Pollen morphology and double fertilization of Phyllostachys edulis

关键词:  毛竹, 花粉形态, 花粉萌发, 双受精作用, 荧光显微技术

Key words:  Phyllostachys edulis, pollen shape, pollen germination, double fertilization, fluorescence microscopic observation

摘要:

由于实验的材料、条件和技术的限制,关于竹类花粉形态、花粉管生长过程的研究十分少见。毛竹(Phyllostachys edulis)属于禾本科(Poaceae/Gramineae)竹亚科(Bambusoideae)植物,在我国广泛分布,具有重要的经济、生态和文化价值。由于其独特的生殖生物学特性,即开花周期长、结籽率低,所以对其开花材料的获取十分困难。该研究在其独特的开花特性基础上,结合野外实地观察,利用显微镜、环境扫描电镜、荧光显微镜等,对毛竹的花粉形态、结构以及花粉管的萌发与生长动态进行了首次报道。结果表明:(1)毛竹花粉近球形,平均直径为61.00 μm,属于大型孢子。(2)毛竹成熟花粉落到雌蕊柱头上后,经过花粉与柱头的成功识别,开始萌发,并形成花粉管; 随着花粉管的逐渐伸长生长,依次经过柱头和花柱,到达子房; 约120 min后到达珠孔处,进入胚珠和胚囊,完成双受精作用。通过对毛竹花粉形态结构和花粉管生长至受精过程的动态观察,为毛竹花粉可授性、花粉生理、生化研究提供了实验技术准备。该研究结果完善和丰富了毛竹乃至整个禾本科植物在生殖生物学方面的研究内容。

Abstract:

Due to the limitations of experimental materials, conditions and techniques, the research on bamboo pollen morphology and the process of pollen tube growth are very rare. Phyllostachys edulis (moso bamboo) (Bambusoideae, Poaceae)is the most important bamboo species, which has large cultivation area and is widely cultivated in China. It has important economic value for its versatile culms and delicious shoots. Besides, moso bamboo also has important ecological and cultural values. It it well known that moso bamboo has a prolonged vegetative phase lasting decades or even longer. The flowering cycle is very long and has low seed setting rate, which leads to the hardness of researching on the flower of P. edulis. Thus, the vegetative(asexual)propagation is the main way of moso bamboo reproduction. In order to investigate the mechanism of blooming of moso bamboo, the pollen's morphology, structure and the growth dynamic of pollen tube of P. edulis were observed by using scanning electron microscope and microscope based on the special blossoming characteristics of moso bamboo, which was the first report about moso bamboo pollen. The results showed that the pollen belonged to large spores. It was subglobose in the scanning electron microscope. The average diameter of pollen was 61.00 μm. The ornamentation of its outer wall was fine granular and has a round germinal aperture. There was a porous circle around the germination aperture. The outer diameter of the germinal aperture was 8.69 μm and the inner diameter was 4.52 μm. The mature pollen of P. edulis fell onto the stigma and began to germinate and formed the pollen tube. After 40 m, a large number of pollen on the stigma began to germinate. The pollen tube grew gradually, through the stigma tissue and stylet, which finally reached to the ovary. After 120 m, the tube reached to the micropyle, and then entered into the ovule and completed fertilization in sac. Finally, the embryo developed into seeds. Through the observation of pollen morphology, germination and double fertilization of P. edulis, this study provides theories and methods for further research on the stigma receptivity, physiological and biochemical of moso bamboo's pollen, improving and enriching the research content of bamboo plant reproductive biology at the same time.