Signature of balancing selection in Arabidopsis
Signature of balancing selection in Arabidopsis
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DOI：
10.1073/pnas.172203599
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发表时间：
2002-08-20
影响因子：
11.1
通讯作者：
Kreitman, M
中科院分区：
文献类型：
--
作者：
Tian, DC;Araki, H;Kreitman, M
自然选择和遗传连锁导致DNA片段具有与所选位点相似的系谱历史。当一个由选择维持的多态性是旧的，它周围将有一个增强的序列变异性岛，这代表了一个可检测的“选择标记”。“我们研究了含有拟南芥抗病基因RPS 5的20 kb间隔内的单核苷酸多态性（SNP）的结构，RPS 5是一个含有整个基因座存在/不存在的共同等位基因的基因座。等位基因在周围的位点上有相当大的分歧，表明选择维持了古老的多态性。“增强的”变异性岛将几个SNP延伸到RPS 5缺失连接的任一侧，并且这些SNP与RPS 5插入/缺失几乎完全连锁不平衡。然而，在距离10 kb的基因座的任何一侧，我们发现低水平的多态性和个别SNP和RP 55等位基因之间的连锁不平衡的情况下。我们的研究结果表明，在拟南芥中这种平衡的多态性周围的增强的变异性的间隔是足够大的，很容易被检测到，但足够小，跨越焦点基因和其他几个。对于这个物种，它应该是可能的，以确定完整的一套基因与长寿的多态性，一个潜在的重要子集的基因分离的功能变体。
Natural selection and genetic linkage cause DNA segments to have genealogical histories resembling those of the selected sites. When a polymorphism maintained by selection is old, it will have an island of enhanced sequence variability surrounding it, which represents a detectable "signature of selection." We investigate the structure of single-nucleotide polymorphisms (SNPs) in a 20-kb interval containing the Arabidopsis thaliana disease resistance gene RPS5, a locus containing common alleles for the presence/ absence of the entire locus. The alleles are considerably diverged at surrounding sites, indicative of an old polymorphism maintained by selection. The island of "enhanced" variability extends several kilobases to either side of the RPS5 deletion junction, and these SNPs are in nearly complete linkage disequilibrium with the RPS5 insertion/deletion. At a distance of 10 kb to either side of the locus, however, we find low levels of polymorphism and the absence of linkage disequilibrium between individual SNPs and RP55 alleles. Our results show that the interval of enhanced variability surrounding this balanced polymorphism in Arabidopsis is large enough to be readily detected, but small enough to span the focal gene and few others. For this species it should be possible to identify the complete set of genes with long-lived polymorphisms, a potentially important subset of genes segregating for functional variants.