Reducing MSH4 copy number prevents meiotic crossovers between non-homologous chromosomes in Brassica napus
Reducing MSH4 copy number prevents meiotic crossovers between non-homologous chromosomes in Brassica napus
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DOI：
10.1038/s41467-019-10010-9
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发表时间：
2019-05-29
影响因子：
16.6
通讯作者：
Jenczewski, Eric
中科院分区：
文献类型：
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作者：
Gonzalo, Adrian;Lucas, Marie-Odile;Jenczewski, Eric
在异源多倍体中，正确的染色体分离需要抑制非同源交换，同时确保同源交换水平。迄今为止，除了面包小麦之外，在异源多倍体中还没有描述能够特异性抑制非同源交换的机制。在这里，我们表明，减少主要交换途径的必需基因 MSH4 的功能拷贝数量，可以防止异源四倍体甘蓝型油菜中的非同源交换。我们发现，非同源交换几乎完全源自 MSH4 依赖性重组途径，并且当 MSH4 在甘蓝型油菜中恢复为单拷贝时，非同源交换的数量会减少；相比之下，同源交叉不受 MSH4 重复丢失的影响。我们还证明，MSH4 在许多独立的多倍体事件之后系统地返回到单拷贝，这种模式可能不是偶然的。这些结果表明，异源多倍体减数分裂的稳定性可以通过关键减数分裂重组基因的丢失来增强。
In allopolyploids, correct chromosome segregation requires suppression of non-homologous crossovers while levels of homologous crossovers are ensured. To date, no mechanism able to specifically inhibit non-homologous crossovers has been described in allopolyploids other than in bread wheat. Here, we show that reducing the number of functional copies of MSH4, an essential gene for the main crossover pathway, prevents non-homologous crossovers in allotetraploid Brassica napus. We show that non-homologous crossovers originate almost exclusively from the MSH4-dependent recombination pathway and that their numbers decrease when MSH4 returns to single copy in B. napus; by contrast, homologous crossovers remain unaffected by MSH4 duplicate loss. We also demonstrate that MSH4 systematically returns to single copy following numerous independent polyploidy events, a pattern that is probably not by chance. These results suggest that stabilization of allopolyploid meiosis can be enhanced by loss of a key meiotic recombination gene.