Contrasted patterns of crossover and non-crossover at Arabidopsis thaliana meiotic recombination hotspots.
Contrasted patterns of crossover and non-crossover at Arabidopsis thaliana meiotic recombination hotspots.
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DOI：
10.1371/journal.pgen.1003922
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发表时间：
2013-11
期刊：
影响因子：
4.5
通讯作者：
Mézard C
中科院分区：
文献类型：
--
作者：
Drouaud J;Khademian H;Giraut L;Zanni V;Bellalou S;Henderson IR;Falque M;Mézard C
绝大多数减数分裂重组事件(交叉(CoS)和非交叉(NCO))聚集在被缺乏重组活性的大区域包围的狭窄热点中。在这里，我们使用了一种新的植物分子鉴定方法，称为“花粉分型”，我们在拟南芥的两个不同的热点区域检测和表征了数百个CO和NCO分子。这一分析表明，Cos集中在几千个碱基的区域，其比率高达基因组平均水平的50倍。热点本身倾向于聚集在大小小于8千个碱基的区域，CO分布重叠。非交叉(NCO)事件也发生在两个热点，但在非常不同的水平(局部CO/NCO比率为1/1和30/1)，它们的轨道长度相当小(几百个碱基对)。我们还发现ZMM蛋白MSH4在CO的形成中发挥了作用，有些出乎意料的是，我们还发现它参与了NCO的生成，但影响程度不同。最后，作用于顺式和反式的因素似乎影响着减数分裂重组热点的Cos的速率和分布。在减数分裂过程中，基因组通过同源染色体之间的重组而重新洗牌。被称为交叉的相互重组事件聚集在几个千碱基宽的称为热点的区域，在这些区域中，它们的频率比邻近区域大大提高。我们对热点组织的理解仅基于对少数物种的分析，不同物种之间的规则也不同。首次对拟南芥中的数百个重组事件进行了分析，揭示了几个新的特征：(I)交换集中在热点中，其频率高达基因组平均水平的50倍；(Ii)非交换事件(也称为与交换无关的基因转换)也发生在热点中，但水平非常不同；(Iii)在没有重组蛋白MSH4的情况下，交换比率显著降低(比野生型水平低70倍)，并且热点内的交换分布也发生了很大程度的改变；出乎意料的是，非交叉率也发生了变化(热点的野生型水平的15%)。最后，我们证明了作用于顺式和反式的因素可能会影响热点上和热点之间的交叉水平和分布。
The vast majority of meiotic recombination events (crossovers (COs) and non-crossovers (NCOs)) cluster in narrow hotspots surrounded by large regions devoid of recombinational activity. Here, using a new molecular approach in plants, called “pollen-typing”, we detected and characterized hundreds of CO and NCO molecules in two different hotspot regions in Arabidopsis thaliana. This analysis revealed that COs are concentrated in regions of a few kilobases where their rates reach up to 50 times the genome average. The hotspots themselves tend to cluster in regions less than 8 kilobases in size with overlapping CO distribution. Non-crossover (NCO) events also occurred in the two hotspots but at very different levels (local CO/NCO ratios of 1/1 and 30/1) and their track lengths were quite small (a few hundred base pairs). We also showed that the ZMM protein MSH4 plays a role in CO formation and somewhat unexpectedly we also found that it is involved in the generation of NCOs but with a different level of effect. Finally, factors acting in cis and in trans appear to shape the rate and distribution of COs at meiotic recombination hotspots. During meiosis, genomes are reshuffled by recombination between homologous chromosomes. Reciprocal recombination events called crossovers are clustered in several kilobase-wide regions called hotspots, where their frequency is greatly enhanced compared to adjacent regions. Our understanding of hotspot organization is based on analyses performed in only a few species and rules differ between species. For the first time, hundreds of recombination events were analyzed in Arabidopsis thaliana revealing several new features: (i) crossovers are concentrated in hotspots where their rate reaches up to 50 times the genome average; (ii) non-crossovers events, (also called gene conversions not associated with crossovers) also occur in hotspots but at very different levels; and (iii) in the absence of the recombination protein MSH4, the crossover rate is dramatically reduced (70 times less than the wild-type level) and the crossover distribution within a hotspot is also largely modified; unexpectedly, the non-crossover rate was also altered (15% of the wild-type level at a hotspot). Finally we showed that factors acting in cis and in trans may influence the level and distribution of crossovers at and between hotspots.
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