华南五针松种皮发育研究

Studies on the Development of Seed Coats of Pinus kwangtungensis

关键词:  种皮  发育  淀粉粒  华南五针松

Key words:  seed coat  development  starch grains  Pinus kwangtungensis

摘要:

运用石蜡切片法,在透射电子显微镜和光学显微镜下观察华南五针松(Pinus kwangtungensis)种皮的形态结构和发育,用PAS反应显示细胞内淀粉粒分布,研究细胞内淀粉粒的含量。结果表明,华南五针松的种皮的发育开始在大孢子母细胞发育的时期,开始时在雌配子体的周围形成比较薄而且致密,颜色较深的几层;随着种子的不断发育,从种子的横切面可见,种皮可以明显分为外种皮,中种皮和内种皮三部分。这三部分种皮的形态结构各有不同:外种皮是几层扁平状硬化薄壁细胞;中种皮细胞较多,细胞层较厚,细胞较大,形状不规则,壁厚;内种皮细胞受到发育的胚的挤压,比较扁小,排列紧密。另外,PAS反应显示出,中种皮与内种皮所含的淀粉粒比较丰富,特别是在种子发育的初期,形成了一层富含淀粉粒的细胞层,这层细胞所含的淀粉粒随着种子的发育越来越少,这与种子发育过程需要分解淀粉粒为细胞分裂提供能量有关。

Abstract:

Paraffin section technique was applied in the study of the development of the seed coat of Pinus kwangtungensis. The results showed that the development of seed coat follows with the development of the megaspore mother cell. In the development of female gametophyte, a thin, dense and dark layer of cells formats around the female gametophyte. With the development of seed, from the cross section, the seed coat is normally composed of three layers:an outer layer, a middle layer and an inter layer. The structures of these three layers are difference. The outer layer of the seed coat consists of several layers of sclerified parenchyma cells whose major axis are flat.The middle layer of the seed coat is thicker in which the cells are bigger and irregular.Squeezed by the developmental embryo, the cells which arrange closely in the inter layer of seed coat are flat and small. In addition, the method of PAS was applied to appear the circumstance of distribution of starch grains. The conclusion shows that the inter layer and the middle layer of seed coats have a lot of starch grains. Especially in the early period of the seed development, it formats a layer which contains many starch grains. These starch grains will reduce graduate with the seed's development. This may be relate with the need of energy to support the cells division which provided by the resolve of the starch grains.