Evolutionary divergence of potential drought adaptations between two subspecies of an annual plant: Are trait combinations facilitated, independent, or constrained?
Evolutionary divergence of potential drought adaptations between two subspecies of an annual plant: Are trait combinations facilitated, independent, or constrained?
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DOI：
10.1002/ajb2.1607
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发表时间：
2021-03
影响因子：
3
通讯作者：
Eckhart VM
中科院分区：
文献类型：
--
作者：
Burnette TE;Eckhart VM
干旱适应机制是否倾向于共同进化，独立进化，或进化受遗传结构的限制还没有完全解决，特别是除了气体交换之外的水关系性状。（柳叶菜科），产于加州，约65，000年前分离，部分由于开花时间的不同而适应，与降水量不同的自然分布区在这些亚种和重组自交系（RILs）从它们之间的杂交，我们得分性状相关的干旱适应（种子发芽和开花，肉质，压力-体积曲线变量的时间）在共同的环境。原生于更干旱环境的亚种（小花）在饱和条件下种子萌发较慢，开花较早，多汁性更强，可能表明上级干旱回避，干旱逃逸和脱水抗性通过储水。其他亚种（xantiana）有较低的渗透势在充分膨压和较低的水势在膨压损失，这意味着上级脱水耐受性。RIL之间的遗传相关性表明促进了某些性状组合的进化和其他性状组合的独立性。在遗传相关性存在的地方，亚种间的差异沿着它们，除了肉质和膨压损失点的差异。在这种情况下，亚种差异克服了遗传相关性，可能反映了强烈的选择和/或拮抗性与其他性状的遗传相关性。 Clarkia xantiana亚种在干旱适应机制上存在差异。遗传结构似乎并没有限制这些机制的进化，它可能促进了一些性状组合的进化。
Whether drought‐adaptation mechanisms tend to evolve together, evolve independently, or evolve constrained by genetic architecture is incompletely resolved, particularly for water‐relations traits besides gas exchange. We addressed this issue in two subspecies of Clarkia xantiana (Onagraceae), California winter annuals that separated approximately 65,000 years ago and are adapted, partly by differences in flowering time, to native ranges differing in precipitation. In these subspecies and in recombinant inbred lines (RILs) from a cross between them, we scored traits related to drought adaptation (timing of seed germination and of flowering, succulence, pressure–volume curve variables) in common environments. The subspecies native to more arid environments (parviflora) exhibited slower seed germination in saturated conditions, earlier flowering, and greater succulence, likely indicating superior drought avoidance, drought escape, and dehydration resistance via water storage. The other subspecies (xantiana) had lower osmotic potential at full turgor and lower water potential at turgor loss, implying superior dehydration tolerance. Genetic correlations among RILs suggest facilitated evolution of some trait combinations and independence of others. Where genetic correlations exist, subspecies differences fell along them, with the exception of differences in succulence and turgor loss point. In that case, subspecies difference overcame genetic correlations, possibly reflecting strong selection and/or antagonistic genetic correlations with other traits. Clarkia xantiana subspecies’ differ in multiple mechanisms of drought adaptation. Genetic architecture generally does not seem to have constrained the evolution of these mechanisms, and it may have facilitated the evolution of some of trait combinations.
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