油杉花粉个体发育中淀粉粒消长变化研究

Studies on Regularity of Accumulation and Disappearance of Starch Grains in Microsporogenesis and Malegametogenesis of Keteleeria fortunei

对油杉小孢子发生、花粉形成和花粉萌发过程中淀粉粒的消长动态作了详细观察。油杉于1月后旬形成花粉母细胞,2月上旬完成减数分裂形成小孢子,小孢子经过连续4次有丝分裂后于2月底形成5细胞型的成熟花粉粒,3月初油杉开始传粉。油杉花粉个体发育中淀粉粒有明显的消长规律,存在2次淀粉粒积累高峰:一次是花粉母细胞进入减数分裂之前,另一次是小孢子进行有丝分裂之前。花粉个体发育中淀粉粒的分布也具规律性:在减I中期淀粉粒逐渐呈赤道区聚积,在减I后期淀粉粒均匀地移向二子核周围,最终淀粉粒平均分配在4个子细胞内;花粉成熟发育期间,淀粉粒聚集在核的周围,散粉前一天成熟花粉中的淀粉粒全部消失,初步鉴定认为,淀粉粒转变为脂肪。在花粉萌发实验中,淀粉粒重新在其花粉管中出现。初步认为,成熟花粉粒中是否积累有淀粉粒并没有系统发育意义,仅是一种传粉生物学特性之一。

The paper dealt with detailed studies on regularity of accumulation and disappearance of starch grains in microsporogenesis, pollen development and pollen germination of Keteleeria fortunei （Murr.） Carr.. The microspore mother cells （MMC） were formed in late January, 2003 and then carried out meiosis from Jan. 26 to Feb. 5. Microspores were released from tetrads on Feb.9. Through four times of continuous mitosis, microspore developed into five-celled pollen grain in later Feb.. The mature pollen consisted of two prothallial cell, a sterile cell, a spermatogenous cell and a tube cell. The pollination occurred in early Mar., lasting about 8 days. The study indicated that starch grains accumulated and disappeared regularly at different phase during pollen development. It was observed that there were two dominant peak accumulation of starch grains. One occurred just before the meiosis of the MMC taking place and another appeared before the microspore beginning mitosis. The amount of starch grains gradually decreased with the division of the cells. And it was showed that the distribution of starch grains changed regularly with the rhythm of pollen development. The starch grains aggregated gradually toward the equatorial region during the metaphase I and then moved to the daughter nucleus during anaphase I , and finally distributed to the four daughter cells equally when the meiosis of the MMC ended. During the maturation of pollen, the starch grains aggregated mainly around the nucleus. All of them disappeared before pollination. The Sudan Ⅲ test indicated that they changed into fat. But they appeared again in the pollen tubes after pollen grains were cultured in vitro and germinated. It was supposed that the reserve of starch grains in mature pollen was in line with ecophysiological adaptations such as the respective pollination syndrome rather than systematics.