南瓜花粉母细胞减数分裂及雄配子体发育研究

Pollen Mother Cell Miosis and Male Gametophyte Development of Pumpkin

[目的]研究南瓜花粉母细胞的减数分裂及其雄配子体发育过程,以期为南瓜花药培养等方面研究提供一定细胞学依据。[方法]采用爱氏苏木精染色-冬青油透明技术对南瓜"天虹"的花粉母细胞减数分裂及其雄配子体发育过程中细胞结构变化和染色体行为进行了观察研究。[结果]南瓜花粉母细胞在细胞核分裂过程中,核膜核仁于中期I消失,末期I重新出现,此时形成2个新月形的细胞核,两核之间出现成膜体,但未出现细胞壁,该成膜体在中期Ⅱ又逐渐消失,末期Ⅱ重新出现。第2次分裂纺锤体中央离心扩散的成膜体与第1次分裂两核相对的中央界面形成的成膜体相连,小孢子细胞壁向心产生。多数四分体中包含四个子细胞,少数还含有额外的小细胞。单核靠边期核仁由1个分解成2～3个或多个,进入有丝分裂前期,成熟花粉为二细胞型。1.0～2.0 cm长花蕾中多数花粉细胞处于单核期,可以将其作为花药或小孢子培养的取材依据。[结论]该研究结果为南瓜细胞遗传学方面的研究奠定了基础。

[Objective] Pollen mother cell miosis and male gametophyte development of pumpkin were observed in this study,to provide some cytological basis for pumpkin anther or microspore culture.[Method] Ehrlich＇s hematoxylin staining-methyl salicylate clearing technique was used for observation and research of the variation of cell structure and chromosomal behavior during pollen mother cell miosis and male gametophyte development of ＇Tianhong＇ pumpkin.[Result] We found that the meiosis in pollen mother cells of pumpkin was simultaneous cytokinesis.In the process of nuclear division,nuclear membrane and nucleolus of pumpkin pollen mother cells gradually disappeared in the metaphaseⅠ and reappeared in telophase Ⅰ,phragmoplast formed between the two generated crescent-shaped nuclei without cell wall,the phragmoplast gradually disappeared in the metaphase Ⅱ and reappeared in telophase Ⅱ.Phragmoplast spread outward from the center of spindle during the second division was connected with that formed on the central interface of two nuclei during the first division,cell wall of microspores generated from periphery to center.Most of the tetrads contained four sub-cells while a few contained extra small cells.During the period of uniuclete microspore at periphery,the single nucleolus split into 2-3 or more small nucleoli,mature pollen grain was two-celled.Mononucleate pollen cells were mostly appeared in the flower buds with length of 1.0-2.0 cm,which could be used as an important indicator to collect materials for anther or microspore culture.[Conclusion] This study had laid the foundation for research of the cytogenetics of pumpkin.