杉木花粉发育过程中形态结构的变化研究

Change of morphological structure during pollen development process in Cunninghamia lanceolate

该研究以扬州地区成年杉木为材料,采用半薄切片法以及扫描电镜和透射电镜观察法,对杉木花粉发育过程进行了观察。结果表明:杉木的造孢细胞形成于10月,持续至翌年的1月底至2月初。造孢细胞位于小孢子囊最里面,呈多边形,数量多且彼此排列紧密;细胞壁很薄,细胞核较大,内含丰富的细胞器和脂类物质。造孢细胞发育成熟后彼此分离形成小孢子母细胞。小孢子母细胞的减数分裂开始于2月下旬,经两次减数分裂,先后形成二分染色体和四分染色体。小孢子从四分体释放后,体积迅速增大,发育形成花粉,这个过程中,伴随着明显的营养物质变化。杉木成熟花粉壁由薄壁区和厚壁区两部分组成,薄壁区中央有一个乳头状突起,突起上有一萌发孔。成熟花粉外壁着生了许多瘤状颗粒。该研究结果为杉木生殖发育、有性繁殖以及系统演化研究提供了重要依据。

Cunninghamia lanceolata is native to China,and it is an important timber tree in South China. Investigation of morphological and structural development of pollen can provide the basis for studying reproductive development,sexual propagation and phylogeny in C. lanceolata. In this study,we selected C. lanceolata from Yangzhou as experimental materials,and investigated the development of pollen using semi-thin section,scanning electron microscopy( SEM) and transmission electron microscopy( TEM). The main results are shown as follows: The sporogenous cells initiated in midOctober,and were located in center of microsporangia,and these cells were polygonal with a dense arrangement. Each sporogenous cell had a thin wall with a large nucleus,and it was rich in organelles and lipids. After separating from each other,some sporogenous cells were developed into microspore mother cells which meiosis occurred in late February. After twice meiotic divisions,dyad and tetrad were formed successively. After the release from the tetrad,mi-crospore enlarged rapidly and then became the mature pollen. Obvious variation of nutrients was observed in this process. The wall of mature pollen consisted of the thin-walled area and the thick-walled area. The center of the thinwalled area was a germinal aperture. There are many warty particles on the surface of pollen exine.