Non-random distribution of extensive chromosome rearrangements in Brassica napus depends on genome organization
Non-random distribution of extensive chromosome rearrangements in Brassica napus depends on genome organization
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DOI：
10.1111/j.1365-313x.2012.04914.x
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发表时间：
2012-05-01
期刊：
影响因子：
7.2
通讯作者：
Jenczewski, Eric
中科院分区：
文献类型：
--
作者：
Nicolas, Stephane D.;Monod, Herve;Jenczewski, Eric
染色体重排很常见，但人们对它们随时间的动态变化、发生机制以及影响其分布和速率的基因组特征仍然知之甚少。我们使用异源单倍体甘蓝型油菜（AC，n = 19）作为模型来分析基因组特征对减数分裂驱动的染色体重排的形成和多样性的影响。我们发现异源单倍体甘蓝型油菜减数分裂导致广泛的新结构多样性。几乎每个异源单倍体后代在整个基因组中都携带有多种重排的独特组合，因此在结构上与其单倍体亲本及其姐妹植物不同。这种大量的基因组重组在杂合状态下的耐受性非常好，因为雄性和雌性的生育力都没有明显降低，并且减数分裂行为在大多数情况下都是正常的。我们还使用了定量统计模型，该模型解释了观察到的重排率变化的 75%，以表明减数分裂驱动的染色体重排的分布不是随机的，而是由三个主要基因组特征决定的。按照重要性降序排列，标记丢失率随着与着丝粒的遗传距离、染色体之间的共线性程度和起源基因组 (A < C) 的增加而强烈增加。总的来说，我们的结果表明甘蓝型油菜积累了大量的遗传变化，但这些重排并不是随机分布在基因组中的。讨论了异源单倍体途径产生的结构遗传多样性及其在多倍体物种进化中与二倍体减数分裂相比的作用。
Chromosome rearrangements are common, but their dynamics over time, mechanisms of occurrence and the genomic features that shape their distribution and rate are still poorly understood. We used allohaploid Brassica napus (AC, n = 19) as a model to analyze the effect of genomic features on the formation and diversity of meiotically driven chromosome rearrangements. We showed that allohaploid B. napus meiosis leads to extensive new structural diversity. Almost every allohaploid offspring carried a unique combination of multiple rearrangements throughout the genome, and was thus structurally differentiated from both its haploid parent and its sister plants. This large amount of genome reshuffling was remarkably well-tolerated in the heterozygous state, as neither male nor female fertility were strongly reduced, and meiosis behavior was normal in most cases. We also used a quantitative statistical model, which accounted for 75% of the observed variation in rearrangement rates, to show that the distribution of meiotically driven chromosome rearrangements was not random but was shaped by three principal genomic features. In descending order of importance, the rate of marker loss increased strongly with genetic distance from the centromere, the degree of collinearity between chromosomes, and the genome of origin (A < C). Overall, our results demonstrate that B. napus accumulates a large number of genetic changes, but these rearrangements are not randomly distributed in the genome. The structural genetic diversity produced by the allohaploid pathway and its role in the evolution of polyploid species compared to diploid meiosis are discussed.