Repeated Evolutionary Changes of Leaf Morphology Caused by Mutations to a Homeobox Gene
Repeated Evolutionary Changes of Leaf Morphology Caused by Mutations to a Homeobox Gene
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DOI：
10.1016/j.cub.2014.06.061
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发表时间：
2014-08-24
期刊：
影响因子：
9.2
通讯作者：
Lenhard, Michael
中科院分区：
文献类型：
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作者：
Sicard, Adrien;Thamm, Anna;Lenhard, Michael
阐明进化中形态变化的遗传基础仍然是生物学的一个主要挑战[1-3]。重复的独立性状变化特别令人感兴趣，因为它们可以指示不同谱系中的适应或产生形态变异的遗传和发育限制[4-6]。在动物中，具有最小多效性和大表型效应的“热点”基因的变化是许多重复形态转变的基础[4-8]。相比之下，只有少数这样的基因已被确定从植物[8-11]，限制了跨王国比较形态进化的原则。在这里，我们证明了简化复杂性（RCO）基因座[12]是菊科中一个以上自然进化的叶形状变化的基础。我们发现，姐妹种荠风疹和荠大花之间的叶缘解剖的差异是由同源异型盒基因RCO-A，这改变了它的活性在叶的发展中的叶片的顺式调控变异。群体遗传学分析表明，C. grandiflora表明活性较高的C.风疹单倍型来源于一种现已罕见或丢失的C. grandiflora单倍型通过额外的突变。在拟南芥中，RCO-A和RCO-B基因的缺失有助于其进化衍生的光滑叶缘[12]，表明RCO基因座是进化热点的候选者。我们还发现，RCO-A的温度响应性表达可以解释的表型可塑性叶片形状的环境温度在荠菜，温度和叶缘解剖之间的负相关性，提出了一个众所周知的分子基础。
Elucidating the genetic basis of morphological changes in evolution remains a major challenge in biology [1-3]. Repeated independent trait changes are of particular interest because they can indicate adaptation in different lineages or genetic and developmental constraints on generating morphological variation [4-6]. In animals, changes to "hot spot" genes with minimal pleiotropy and large phenotypic effects underlie many cases of repeated morphological transitions [4-8]. By contrast, only few such genes have been identified from plants [8-11], limiting cross-kingdom comparisons of the principles of morphological evolution. Here, we demonstrate that the REDUCED COMPLEXITY (RCO) locus [12] underlies more than one naturally evolved change in leaf shape in the Brassicaceae. We show that the difference in leaf margin dissection between the sister species Capsella rubella and Capsella grandiflora is caused by cis-regulatory variation in the homeobox gene RCO-A, which alters its activity in the developing lobes of the leaf. Population genetic analyses in the ancestral C. grandiflora indicate that the more-active C. rubella haplotype is derived from a now rare or lost C. grandiflora haplotype via additional mutations. In Arabidopsis thaliana, the deletion of the RCO-A and RCO-B genes has contributed to its evolutionarily derived smooth leaf margin [12], suggesting the RCO locus as a candidate for an evolutionary hot spot. We also find that temperature-responsive expression of RCO-A can explain the phenotypic plasticity of leaf shape to ambient temperature in Capsella, suggesting a molecular basis for the well-known negative correlation between temperature and leaf margin dissection.