巴西橡胶树种子发育过程中淀粉积累动态

Accumulation and Movement of Starch during Seed Development of Hevea brasiliensis

对橡胶种子发育过程中各构成部分淀粉的积累和消失进行显微观察，结果如下：（１） 在大孢子母细胞早期胚珠组织尚未出现淀粉时，子房壁外层细胞就出现淀粉粒，曾一度随着 组织的生长淀粉的积累迅速增加；到大孢子母细胞晚期，内珠被和珠心组织开始淀粉积累时， 子房壁淀粉含量迅速下降。（２）外珠被淀粉积累开始比珠心与内珠被早，但淀粉含量增长平 缓，一直处于较低矮的水平，至４－细胞原胚期淀粉已全部消失，与受精作用和胚的发育关系 很小。（３）内珠被淀粉的积累呈现３个高峰期，分别出现在胚囊成熟期，合子休眠期和原胚 发育期，为受精作用、合子分裂和胚器官分化提供必需的养料，它们之间关系密切。（４）胚囊 成熟期，尤其受精作用前夕，珠心淀粉积累达到高峰，细胞中充满淀粉，受精作用后珠心淀粉 含量迅速下降，至授粉后３０ ｄ全部消失。合子分裂经球形胚到心形胚阶段近 ２个月期间珠 心一直没有淀粉积累，至胚胎发育后期器官分化阶段，珠心才重新迅速积累淀粉并最终发育 形成外胚乳。

Accumulation and movement of starch in various parts of seed during development was observed microscopically. The results were as follows: (1) Starch grains in the outer layer of the ovary wall occurred in the early stage of macro spore mother cell development, when the starch of ovule did not appear. The amount of starch within ovary increased with the development of ovary and ovule. At the later stage of macro spore mother cell development, the quantity of starch within ovary wall diminished rapidly while starch grains occurred in the inner-integument and nucellus; (2) Accumulation of starch within outer-integument took place earlier than those in inner-integu- ment and nucellus, while the amount of starch increased slowly, and was always in a lower level and disappeared at 4-cell proembryo stage. It was suggested that accumulation of starch within outer-integument was little correlative with embryo development; (3) Accumulation of starch in inner-integument presented as three peaks which appeared at embryo sac maturity, zygote dormancy and proembryo development respectively. It provided nutrients needed for the fertilization, zygote division and embryo differentiation. There was a close relation between them; (4) Accumulation of starch within nucellus reached the peak and the cells were filled with starch grains when the embryo sac matured, especially before fertilization. The quantity of starch decreased rapidly after fer- tilization and disappeared 30 days after pollination. During zygote-division, from sphere-embryo to heart-embryo, no starch grins were found within nucellus which however deposited starch again as the embryo began to differentiate and finally developed into perisperm.