Diplosporous embryo-sac formation and the degree of diplospory inAllium tuberosum
Diplosporous embryo-sac formation and the degree of diplospory inAllium tuberosum
复制标题
马铃薯双孢子胚囊的形成及双孢子化程度
作者：
A. Kojima;Y. Nagato
为了获得兼性无融合生殖体韭菜（Allium tuberosum）（2n = 32）孢子形成过程的动态和定量信息，我们采用透明染色压片法对韭菜“嫩极”（Tender-Pole）的雌性减数分裂和胚囊发育全过程进行了细胞学观察。根据花蕾长度和开花前天数建立了其进程时间表。在减数分裂的最早阶段，观察到成对的染色体丝，之后发展出32个同源二价体。因此，核内复制一定发生在减数分裂前间期或雌性减数分裂开始时。这种内复制减数分裂也发生在雄性侧，但频率（3.9%）远低于雌性侧（80%）。以胚囊母细胞加倍率计算的倍数孢子体形成程度在6个品种间有一定的差异，以“呼和浩特”和“满洲”的倍数孢子体形成程度最高（98%），"高雄“最低（76%）。
SummaryTo obtain information on the dynamic and quantitative aspects of displospory in a facultative apomict,Allium tuberosum (2n = 32), we cytologically observed the entire course of female meiosis and embryosac development in cv ‘Tender-Pole’ by the clearing-staining-squash method. A time-table of its course was constructed in terms of bud length and days pre-anthesis. Chromosome threads were observed in pairs at the earliest stage of meiosis, after which 32 autobivalents developed. Thus, endoreduplication must have occurred during premeiotic interphase or at the onset of female meiosis. Such endoreduplicational meiosis also occurred on the male side, though the frequency (3.9%) was much lower than that on the female side (80%). The degree of diplospory calculated as the percentage of reduplicated embryo-sac mother cells varied to some extent among six cultivars: ‘Huhehaote’ and ‘Manchuria’ showed the highest degree of diplospory (98%), and ‘Kaohsiung’ the lowest (76%).