Heterosis is prevalent among domesticated but not wild strains of Saccharomyces cerevisiae.
Heterosis is prevalent among domesticated but not wild strains of Saccharomyces cerevisiae.
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DOI：
10.1534/g3.113.009381
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发表时间：
2014-02-19
期刊：
影响因子：
--
通讯作者：
Korona R
中科院分区：
文献类型：
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作者：
Plech M;de Visser JA;Korona R
近亲繁殖但不相关的个体之间的杂交通常会导致后代适应性的增加。这种现象被称为杂种优势，并已报告野生和驯化的植物和动物种群。杂种优势的分析常常受到这样一个事实的阻碍，即所分析的生物体之间的遗传相关性只是大致知道的。我们研究了一系列来自野生和人类创造的栖息地的酿酒酵母分离株，其基因组被测序，因此它们的相关性是完全已知的。我们推断，如果这些菌株以近似恒定的速率积累不同的有害突变，那么杂种优势应该在来自最不相关亲本的F1杂合子中最明显。我们发现，杂种优势是实质性的和正相关的序列分歧，但只有在驯化菌株。超过80%的杂合杂种比其纯合亲本的平均值更适合，其中约四分之三甚至超过了最适合的亲本。我们的研究结果支持这样的观点，即驯化带来了选择的放松和有害突变的积累。然而，其他因素也可能起作用。特别是，所观察到的遗传负荷的积累可能是由于近亲繁殖率的降低而不是增加。
Crosses between inbred but unrelated individuals often result in an increased fitness of the progeny. This phenomenon is known as heterosis and has been reported for wild and domesticated populations of plants and animals. Analysis of heterosis is often hindered by the fact that the genetic relatedness between analyzed organisms is only approximately known. We studied a collection of Saccharomyces cerevisiae isolates from wild and human-created habitats whose genomes were sequenced and thus their relatedness was fully known. We reasoned that if these strains accumulated different deleterious mutations at an approximately constant rate, then heterosis should be most visible in F1 heterozygotes from the least related parents. We found that heterosis was substantial and positively correlated with sequence divergence, but only in domesticated strains. More than 80% of the heterozygous hybrids were more fit than expected from the mean of their homozygous parents, and approximately three-quarters of those exceeded even the fittest parent. Our results support the notion that domestication brings about relaxation of selection and accumulation of deleterious mutations. However, other factors may have contributed as well. In particular, the observed build-up of genetic load might be facilitated by a decrease, and not increase, in the rate of inbreeding.