Outcrossing, mitotic recombination, and life-history trade-offs shape genome evolution in Saccharomyces cerevisiae
Outcrossing, mitotic recombination, and life-history trade-offs shape genome evolution in Saccharomyces cerevisiae
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DOI：
10.1073/pnas.1012544108
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发表时间：
2011-02-01
影响因子：
11.1
通讯作者：
Murray, Debra
中科院分区：
文献类型：
--
作者：
Magwene, Paul M.;Kayikci, Oemuer;Murray, Debra
我们对酿酒酵母二倍体菌株进行了群体基因组调查，发现许多萌芽酵母菌株具有很高的基因组杂合度，其中很大一部分可能是由于异交。我们证明了菌株间杂合性的差异与生活史上的权衡有关，该权衡涉及在营养胁迫下酵母如何从无性繁殖转变为有性繁殖。这种权衡反映在孢子形成效率和假菌丝发育之间的负相关关系，并与RME1表达的变化有关，RME1是一种对减数分裂和丝状生长具有多效性的转录因子。在自然和人类相关的环境中选择不同的生活史策略可能有助于通过影响酵母谱系经历有性周期的频率从而提供近亲繁殖的机会，从而不同地维持基因组的杂合性。除了杂合性水平升高外，许多菌株还表现出较大的杂合性缺失(LOH)基因组区域，这表明有丝分裂重组对该物种的遗传变异有重大影响。这项研究对异交和有丝分裂重组在塑造酿酒酵母基因组结构中所起的作用提供了新的见解。这项研究还提供了一个独特的案例，在这个案例中，相同物种的个体之间遗传变异的基因组分布的显著差异可以在很大程度上用生活史的权衡来解释。
We carried out a population genomic survey of Saccharomyces cerevisiae diploid isolates and find that many budding yeast strains have high levels of genomic heterozygosity, much of which is likely due to outcrossing. We demonstrate that variation in heterozygosity among strains is correlated with a life-history trade-off that involves how readily yeast switch from asexual to sexual reproduction under nutrient stress. This trade-off is reflected in a negative relationship between sporulation efficiency and pseudohyphal development and correlates with variation in the expression of RME1, a transcription factor with pleiotropic effects on meiosis and filamentous growth. Selection for alternate life-history strategies in natural versus human-associated environments likely contributes to differential maintenance of genomic heterozygosity through its effect on the frequency that yeast lineages experience sexual cycles and hence the opportunity for inbreeding. In addition to elevated levels of heterozygosity, many strains exhibit large genomic regions of loss-of-heterozygosity (LOH), suggesting that mitotic recombination has a significant impact on genetic variation in this species. This study provides new insights into the roles that both outcrossing and mitotic recombination play in shaping the genome architecture of Saccharomyces cerevisiae. This study also provides a unique case where stark differences in the genomic distribution of genetic variation among individuals of the same species can be largely explained by a life-history trade-off.