麻疯树花药发育过程中Ca2+的分布特征

采用超薄切片技术,在透射电镜下观察麻疯树(Jatropha curcasL.)花药发育过程中Ca2 的分布特征。在孢原细胞时期的花药中几乎看不到Ca2 沉淀,但花药维管束周围的细胞中有较多的Ca2 沉淀;到小孢子母细胞时期,细胞质中Ca2 沉淀依然较少,绒毡层壁上Ca2 沉淀明显增多;四分体形成时,小孢子细胞质和绒毡层细胞质中出现了较多的Ca2 沉淀;在小孢子发育早期,细胞质中Ca2 沉淀增加不明显,花粉壁部位累积有很多的Ca2 沉淀,绒毡层中Ca2 沉淀数量达到最多;到小孢子发育晚期,小孢子大液泡的液泡膜上有大量的Ca2 沉淀,绒毡层中Ca2 沉淀明显减少;随着二胞花粉中的大液泡消失,细胞质中积累淀粉粒以后,花粉中看到的Ca2 沉淀极少,同时,在花药维管束周围的薄壁细胞中,又出现了较多的Ca2 沉淀,表明花粉对Ca2 的需求可能降低。麻疯树花药发育过程中钙的动态分布特征暗示着钙参与了调控花粉发育过程,Ca2 的运输途径是由药隔薄壁组织运输到绒毡层,再进一步转移到小孢子表面和细胞质中,整个花药发育过程中,Ca2 沉淀表现为少—增加—减少的变化趋势。

Character of Calcium Distribution during the Anther Development of Jatropha curcas L.

Calcium distribution during the anther development of Jatropha curcas L. was observed under trans-mission electron microscopy by ultra-thin sectioning. At the sporogenous cell stage, very few calcium precipitates are found in the anther, but they are accumulated in the parenchymatous cells outside the vascular bundles. At the microspore mother cell stage, there are still few calcium precipitates in cytoplasm, but abundant calcium precipitates accumulate in the tapetal cell walls. After the tetrads form, abundant calcium precipitates appear in the cytoplasm of the microspores and tapetal cells. At the early microspore stage, numerous calcium precipitates accumulate in the microspore intine and abundant precipitates are found in the tapetal cells. At the late microspore stage, calcium precipitates accumulate on the vacuole membrane, but decrease in the tapetal cells. As starch grains accumulate in the mature pollen, very little calcium is found. At the same time, some calcium precipitates accumulate in the parenchymatous cells outside the vascular bundles. The character of calcium distribution during anther development of Jatropha curcas means that calcium plays some roles in biological significance during microspore development. Calcium precipitates are transported from the connective parenchyma cells into the tapetal cells, and they are transported into the pollen wall and cytoplasm. Quantity of calcium in the anthers during its whole developmental progress showed a changing tendency of few-increase-decrease.