Polygenic evolution of a sugar specialization trade-off in yeast.
Polygenic evolution of a sugar specialization trade-off in yeast.
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DOI：
10.1038/nature16938
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发表时间：
2016-02-18
期刊：
影响因子：
64.8
通讯作者：
Brem RB
中科院分区：
文献类型：
--
作者：
Roop JI;Chang KC;Brem RB
新性状的进化可能涉及分散在整个基因组中的许多突变。检测和验证这样一组等位基因，特别是如果它们很久以前就出现了，仍然是进化遗传学的一个关键挑战。在这里，我们剖析了一个进化权衡前所未有的遗传复杂性之间的长期分歧的物种。在添加半乳糖的1%葡萄糖培养基中培养，酿酒酵母（Saccharomyces cerevisiae），而S. bayanus或其他酵母属物种延迟半乳糖代谢，直到葡萄糖耗尽。从S.酿酒酵母，当一起引入到S. bayanus在1%葡萄糖-半乳糖培养基中基本上概括了延迟表型，并且在隔离测试时大多数具有部分作用。GAL编码区的变异也导致了在1%葡萄糖-半乳糖培养基中单独测试时的延迟。当结合时，S. cerevisiae GAL编码区引起了S. bayanus背景。在含2.5%葡萄糖和半乳糖的培养基中，野生型S.酿酒酵母抑制GAL基因表达，相对于S. bayanus的转基因;酿酒酵母GAL启动子等位基因或GAL编码区足以部分重建这些表型。S.因此，酿酒酵母GAL基因编码缓慢诱导和强烈抑制的调节程序，并且在葡萄糖-半乳糖转换期间对适应性有害，但在葡萄糖过量时有益。总之，这些结果清楚地表明，复杂表型的遗传图谱是触手可及的，即使在分歧很大的物种。
The evolution of novel traits can involve many mutations scattered throughout the genome. Detecting and validating such a suite of alleles, particularly if they arose long ago, remains a key challenge in evolutionary genetics. Here we dissect an evolutionary tradeoff of unprecedented genetic complexity between long-diverged species. When cultured in 1% glucose medium supplemented with galactose, Saccharomyces cerevisiae, but not S. bayanus or other Saccharomyces species, delayed commitment to galactose metabolism until glucose was exhausted. Promoters of seven galactose (GAL) metabolic genes from S. cerevisiae, when introduced together into S. bayanus, largely recapitulated the delay phenotype in 1% glucose-galactose medium, and most had partial effects when tested in isolation. Variation in GAL coding regions also contributed to the delay when tested individually in 1% glucose-galactose medium. When combined, S. cerevisiae GAL coding regions gave rise to profound growth defects in the S. bayanus background. In medium containing 2.5% glucose supplemented with galactose, wild-type S. cerevisiae repressed GAL gene expression and had a robust growth advantage relative to S. bayanus; transgenesis of S. cerevisiae GAL promoter alleles or GAL coding regions was sufficient for partial reconstruction of these phenotypes. S. cerevisiae GAL genes thus encode a regulatory program of slow induction and avid repression, and a fitness detriment during the glucose-galactose transition but a benefit when glucose is in excess. Together, these results make clear that genetic mapping of complex phenotypes is within reach, even in deeply diverged species.