The genome-wide dynamics of purging during selfing in maize
The genome-wide dynamics of purging during selfing in maize
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DOI：
10.1038/s41477-019-0508-7
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发表时间：
2019-09
期刊：
影响因子：
18
通讯作者：
Kyria A Roessler;A. Muyle;C. M. Díez;Garren Gaut;Alexandros Bousios;Michelle C. Stitzer;Danelle K. Seymour;J. Doebley;Qingpo Liu;B. Gaut
中科院分区：
文献类型：
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作者：
Kyria A Roessler;A. Muyle;C. M. Díez;Garren Gaut;Alexandros Bousios;Michelle C. Stitzer;Danelle K. Seymour;J. Doebley;Qingpo Liu;B. Gaut
自体受精（也称为自交）是植物重要的繁殖策略，也是植物遗传学和植物育种广泛应用的工具。自交可能会通过发现隐性有害变异而导致近交衰退，除非这些变异通过选择被清除。在这里，我们研究了一组 11 个自交六代玉米品系的清除动态。我们发现杂合的、假定有害的单核苷酸多态性在自交过程中优先从基因组中丢失。有害的单核苷酸多态性在高重组区域中丢失得更快，大概是因为重组通过解偶联连锁变体提高了选择效率。总体而言，杂合性下降速度比预期慢，估计每代下降 35% 至 40%，而不是预期的 50%，这可能反映了普遍的联想过度主导。最后，由于转座元件的清除，三个品系的基因组大小显着减小。对于始于具有更多转座元件和染色体旋钮的较大基因组的谱系，更可能发生基因组丢失。这三个品系在短短几代内就从其基因组中平均清除了 398 Mb，相当于每个谱系的三个拟南芥基因组。
Self-fertilization (also known as selfing) is an important reproductive strategy in plants and a widely applied tool for plant genetics and plant breeding. Selfing can lead to inbreeding depression by uncovering recessive deleterious variants, unless these variants are purged by selection. Here we investigated the dynamics of purging in a set of eleven maize lines that were selfed for six generations. We show that heterozygous, putatively deleterious single nucleotide polymorphisms are preferentially lost from the genome during selfing. Deleterious single nucleotide polymorphisms were lost more rapidly in regions of high recombination, presumably because recombination increases the efficacy of selection by uncoupling linked variants. Overall, heterozygosity decreased more slowly than expected, by an estimated 35% to 40% per generation instead of the expected 50%, perhaps reflecting pervasive associative overdominance. Finally, three lines exhibited marked decreases in genome size due to the purging of transposable elements. Genome loss was more likely to occur for lineages that began with larger genomes with more transposable elements and chromosomal knobs. These three lines purged an average of 398 Mb from their genomes, an amount equivalent to threeArabidopsis thalianagenomes per lineage, in only a few generations.