Asynchronous meiotic rhythm as the cause of selective chromosome elimination in an interspecific Brachiaria hybrid
Asynchronous meiotic rhythm as the cause of selective chromosome elimination in an interspecific Brachiaria hybrid
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DOI：
10.1007/s00299-004-0784-0
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发表时间：
2004-03
影响因子：
6.2
通讯作者：
C. Risso-Pascotto;M. S. Pagliarini;C. Borges do Valle;L. Jank
中科院分区：
文献类型：
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作者：
C. Risso-Pascotto;M. S. Pagliarini;C. Borges do Valle;L. Jank
本文报道了Brachiaria ruziziensis(2n=2x=18)有性二倍体种质(SEX)和B.无融合生殖四倍体种质(APO)之间的种间杂种小孢子发生过程中染色体消除的发生。 brizantha(2n=4x=36)。三倍体杂种的减数分裂非常异常（2n=3x=27）；我们观察到从中期 I 到减数分裂结束的明显不同步。 APO 和 SEX 基因组没有表现出相同的减数分裂节律。当前者（具有九个二价体）处于中期 I 时，九个 SEX 单价体尚未对齐；当后者到达平板时，APO 基因组已处于后期。在随后的阶段中，APO 基因组已到达两极，而 SEX 正在经历姐妹染色单体分离。由于 SEX 基因组总是在时间上落后，所以它在每个极中产生了一个额外的核。在第二次分裂中，行为相同，但 SEX 基因组没有发生后期 II，并且在末期 II 的每个细胞中仅观察到一个外核。 SEX 基因组的染色体消除范围从部分到全部。讨论了这些发现对于臂形藻育种计划的重要性。
This paper reports the occurrence of chromosome elimination during microsporogenesis in an interspecific hybrid between a sexual diploid accession (SEX) ofBrachiaria ruziziensis(2n=2x=18) and an apomictic tetraploid accession (APO) ofB. brizantha(2n=4x=36). Meiosis was very abnormal in the triploid hybrid (2n=3x=27); we observed a distinct asynchrony from metaphase I to the end of meiosis. The APO and the SEX genomes did not show the same meiotic rhythm. When the former, with nine bivalents, was in metaphase I, the nine SEX univalents were not yet aligned; when the latter reached the plate, the APO genome was already in anaphase. In subsequent stages, the APO genome had reached the poles while the SEX was undergoing sister-chromatid segregation. As the SEX genome always remained temporally behind, it gave rise to one extra-nucleus in each pole. In the second division, the behavior was the same but anaphase II did not occur for the SEX genome, and only one extra-nucleus was observed in each cell in telophase II. Chromosome elimination for the SEX genome ranged from partial to total. The importance of these findings with respect toBrachiariabreeding programmes is discussed.