Natural variation in GL1 and its effects on trichome density in Arabidopsis thaliana
Natural variation in GL1 and its effects on trichome density in Arabidopsis thaliana
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DOI：
10.1111/j.1365-294x.2012.05630.x
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发表时间：
2012-07-01
影响因子：
4.9
通讯作者：
Symonds, V. V.
中科院分区：
文献类型：
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作者：
Bloomer, R. H.;Juenger, T. E.;Symonds, V. V.
对生物多样性如何产生、维持和丧失的最终理解取决于确定负责的基因。尽管在过去的几十年里，人们对基因功能有了很多发现，但对基因效应（即基因的自然变异如何导致表型的自然变异）的了解却少之又少。拟南芥的毛状体密度是研究自然分子和表型变异的理想性状，因为毛状体的起始具有良好的遗传特征，并且毛状体密度在自然群体中和群体之间变化很大。在这里，我们发现 GLABRA1 (GL1)（一种 R2R3 MYB 转录因子基因，在毛状体起始中发挥作用）的变异对拟南芥天然种质中的毛状体密度具有定性和可能的定量影响。具体来说，我们描述了 GL1 的四个独立的功能丧失等位基因，每个都产生无毛表型。此外，我们发现仅限于 GL1 位点的常见多态性模式与毛状体密度的定量变化相关。虽然导致无毛表型的突变主要是编码变化，但导致数量变异的模式跨越编码区和调控区。这些数据表明GL1是拟南芥内毛状体密度变异的重要来源，并且与最近的报道一起表明TTG1表皮细胞命运途径通常可能是天然毛状体密度变异的关键分子遗传来源，也是分子进化研究的重要模型。
The ultimate understanding of how biological diversity arises, is maintained, and lost depends on identifying the genes responsible. Although a good deal has been discovered about gene function over the past few decades, far less is understood about gene effects, that is, how natural variation in a gene contributes to natural variation in phenotypes. Trichome density in Arabidopsis thaliana is an ideal trait for studies of natural molecular and phenotypic variation, as trichome initiation is genetically well-characterized and trichome density is highly variable in and among natural populations. Here, we show that variation at GLABRA1 (GL1), an R2R3 MYB transcription factor gene, which has a role in trichome initiation, has qualitative and likely quantitative effects on trichome density in natural accessions of A. thaliana. Specifically, we characterize four independent loss-of-function alleles for GL1, each of which yields a glabrous phenotype. Further, we find that a pattern of common polymorphisms confined to the GL1 locus is associated with quantitative variation for trichome density. While mutations resulting in a glabrous phenotype are primarily coding changes, the pattern resulting in quantitative variation spans both coding and regulatory regions. These data show that GL1 is an important source of trichome density variation within A. thaliana and, along with recent reports, suggest that the TTG1 epidermal cell fate pathway generally may be the key molecular genetic source of natural trichome density variation and an important model for the study of molecular evolution.