红皮云杉花粉母细胞减数分裂和花粉发育的研究

Studies on the Meiosis of Pollen Mother Cell and Pollen Development of Picea koraiensis Nakai

采用压片法观察研究了红皮云杉花粉母细胞(PMC)减数分裂和花粉发育的完整过程,证实红皮云杉PMC减数分裂始于每年春季,持续时间2～3个月。减数分裂中期二价体构型以两臂至少发生两次交换的环形二价体居多,很少观察到棒状二价体。减数分裂粗线期结束之后经历明显的弥散双线期阶段。胞质分裂发生在第二次减数分裂结束之后,属于同时型分裂方式,形成的四分体主要是四面体形。四分体的构型还受到第二次减数分裂中期纺锤体定向的影响,其中纺锤体垂直排列形成的四分体为四面体形,而纺锤体平行排列形成的四分体为四角形。四分体在胼胝酶的作用下释放出单核小孢子。红皮云杉单核小孢子经过3次不对称有丝分裂,形成4细胞的成熟花粉,包括2个原叶细胞,1个生殖细胞和1个管细胞。云杉属花粉的发育与松属基本相同,成熟花粉均由4个细胞组成。

Using the squashing technique, meiosis and pollen development of Picea koraiensis were investigated. Our results showed that meiosis of Picea koraiensis started in spring and last about 2 - 3 months. The main configuration of bivalents was the ring ones caused by more than two times of chromosome exchanges on the arms. The rod-bivalents produced by chromosome exchange at only one arm were rarely observed. The microscopic appearance of meiosis in this species showed pronounced diffuse stage between pachytene and diplotene. Cytokinesis of Picea koraiensis is simultaneous type, resulting in tetrahedral tetrads. However, tetrad configurations were also affected by the orientations of the second meiotic axes leading to the formation of dif- ferent shaped tetrads. At metaphase 11, the spindle axis was occasionaXly oriented parallel to each other instead of perpendicular as expect theoretically, then the four haploid nuclei were kept in a transitory syncytium in tetragon. After callose wall was dissolved, independent single-nucleus pollens formed. After then, the haploid nucleolus underwent three cycles of mitotic division, resulting in the formation of four-celled pollen with two prothallial cells, one body cell and one tube cell. The pollen development of Picea koraiemis is similar to that recorded in Pinus.