减数分裂是有性生殖的一个关键过程,细胞分裂过程中的错误会显著影响生育力。成功的减数分裂依赖于参与DNA复制的众多基因的协调作用,断线,随后重新加入。DNA拓扑异构酶通过调节DNA拓扑结构发挥着至关重要的作用,缓解复制和转录过程中的紧张。为了阐明DNA拓扑异构酶1α(AtTOP1α)在拟南芥雄性生殖发育中的特定功能,我们研究了拟南芥花蕾的减数分裂细胞分裂。结合细胞学和生化技术,我们的目的是揭示AtTOP1α对减数分裂的新贡献。我们的结果表明,缺乏AtTOP1α会导致减数分裂过程中的染色质行为异常。具体来说,top1α1突变体在减数分裂早期显示出改变的异染色质分布和聚集的着丝粒信号。此外,该突变体表现出45srDNA信号分布的破坏和中期I期间chiasma形成的频率降低,基因交换的关键阶段.此外,atm-2×top1α1双突变体表现出更严重的减数分裂缺陷,包括不完全的突触,DNA片段化,和polyads的存在。这些观察结果共同表明,AtTOP1α在确保减数分裂的准确进展中起着关键作用,促进同源染色体交叉形成,并可能在拟南芥小孢子母细胞中与突变的共通DNA修复途径中起作用。
Meiosis is a critical process in sexual reproduction, and errors during this cell division can significantly impact fertility. Successful meiosis relies on the coordinated action of numerous genes involved in DNA replication, strand breaks, and subsequent rejoining. DNA topoisomerase enzymes play a vital role by regulating DNA topology, alleviating tension during replication and transcription. To elucidate the specific function of DNA topoisomerase 1α ( A t T O P 1 α ) in male reproductive development of Arabidopsis thaliana, we investigated meiotic cell division in Arabidopsis flower buds. Combining cytological and biochemical techniques, we aimed to reveal the novel contribution of A t T O P 1 α to meiosis. Our results demonstrate that the absence of A t T O P 1 α leads to aberrant chromatin behavior during meiotic division. Specifically, the top1α1 mutant displayed altered heterochromatin distribution and clustered
centromere signals at early meiotic stages. Additionally, this mutant exhibited disruptions in the distribution of 45s rDNA signals and a reduced frequency of chiasma formation during metaphase I, a crucial stage for genetic exchange. Furthermore, the atm-2×top1α1 double mutant displayed even more severe meiotic defects, including incomplete synapsis, DNA fragmentation, and the presence of polyads. These observations collectively suggest that A t T O P 1 α plays a critical role in ensuring accurate meiotic progression, promoting homologous chromosome crossover formation, and potentially functioning in a shared DNA repair pathway with ATAXIA TELANGIECTASIA MUTATED (ATM) in Arabidopsis microspore mother cells.