人工合成甘蓝型油菜减数分裂中的染色体行为观察

Observation on Chromosome Behavior during Meiosis of Resynthesized B.napus

以白菜(Brassica rapaL.,2n=20,AA)为母本,芥蓝(B.oleraceaL.,2n=18,CC)为父本,通过种间杂交、子房培养和染色体加倍,获得新合成甘蓝型油菜(B.napusL.,2n=38,AACC)株系35个。细胞学观察结果表明,新合成甘蓝型油菜的花粉母细胞(PMCs)内染色体在早双线期聚集成两个染色体群,具有较为明显的界限;随后逐渐形成单个二价体,直至终变期产生全部19个二价体,或一些四价体和二价体;在个别PMCs内19个二价体呈9∶10的分开排列;在后期Ⅰ/末期Ⅰ以及第二次减数分裂过程中,染色体分离较为正常。在讨论中提出甘蓝型油菜的染色体在长期的进化过程中所产生的结构变异可能主要来自于A、C基因组内部染色体间交换的假说。

Using B. oleracea as paternal plants and B. rapa as maternal plants, 35 lines of resynthesized B. napus were obtained by means of ovary culture and chromosome doubling. The cytological observation showed that separation and asynchronous division of two groups of chromosomes existed in early diplonema in most PMCs of resynthesized B. napus and they remained relatively independ- ent with obvious limit： Then they paired each other as bivalents until formed 19 bivalents or some quadrivalents and bivalents; in some PMCs, 19 bivalents appeared apart arrangement at the ratio of 9： 10. During meiosis at anaphase I and telophase I, as well as meiosis II, chromosome behavior was generally normal. In the discussion, we gave the hypothesis that structural variation might come from the exchange between chromosomes of A or C genome in the long term evolution of chromosomes in B. napus.