A major locus controls local adaptation and adaptive life history variation in a perennial plant

First author: Jing Wang; Affiliations: Umeå University (于默奥大学): Umeå, Sweden

Corresponding author: Pär K. Ingvarsson

The initiation of growth cessation and dormancy represent critical life-history trade-offs between survival and growth and have important fitness effects in perennial plants. Such adaptive life-history traits often show strong local adaptation along environmental gradients but, despite their importance, the genetic architecture of these traits remains poorly understood. We integrate whole genome re-sequencing with environmental and phenotypic data from common garden experiments to investigate the genomic basis of local adaptation across a latitudinal gradient in European aspen (Populus tremula). A single genomic region containing the PtFT2 gene mediates local adaptation in the timing of bud set and explains 65% of the observed genetic variation in bud set. This locus is the likely target of a recent selective sweep that originated right before or during colonization of northern Scandinavia following the last glaciation. Field and greenhouse experiments confirm that variation in PtFT2 gene expression affects the phenotypic variation in bud set that we observe in wild natural populations. Our results reveal a major effect locus that determines the timing of bud set and that has facilitated rapid adaptation to shorter growing seasons and colder climates in European aspen. The discovery of a single locus explaining a substantial fraction of the variation in a key life-history trait is remarkable, given that such traits are generally considered to be highly polygenic. These findings provide a dramatic illustration of how loci of large-effect for adaptive traits can arise and be maintained over large geographical scales in natural populations.

生长的停止和休眠代表了植物生活史在存活和生长之间的平衡，并且对于多年生植物的适应性具有非常重要的影响。具有这种适应性生活史性状的植物通常沿着环境梯度存在非常强的区域性适应能力，但除了知道这些性状具有非常重要的作用，它们潜在的遗传结构还不是很清楚。本文作者整合了全基因组重测序、环境和表型数据研究了来自同质园实验的欧洲山杨在不同纬度梯度上区域适应性的遗传基础。一个包含PtFT2基因的基因组区域介导了欧洲山杨出芽时间的区域适应性，解释了65%的出芽遗传变异。该位点可能是最近一次选择性清除（selective sweep）的靶位点，该选择性清除源自于最近一次冰期后欧洲山杨在斯堪的纳维亚北部的扩张。田间和温室试验显示PtFT2基因表达的变异影响出芽时间的表型变异，这与在野外自然群体中所观察到的一致。本文的结果揭示了欧洲山杨中一个决定出芽时间的主效位点，促进其能够适应更短的生长季节和更冷的气候。考虑到这些性状大多是由多个基因所决定的，因此能够鉴定到单个位点就能解释某个关键生活史性状相当大的一部分变异是非常有意义的。本文的研究揭示了植物自然群体中对于适应性性状具有较大影响的位点是如何产生的，以及如何在大尺度的地理分布上维持。

A selective sweepis the reduction or elimination of variation among the nucleotides in neighboring DNA of a mutation as the result of recent and strong positive natural selection.

通讯：Pär K. Ingvarsson (http://www.pkilab.org/wp/people/)

个人简介：1991年，瑞典隆德大学，生物学和数学学士；1997年，瑞典于默奥大学，生态植物学博士。

研究方向：植物是如何通过响应生物和非生物因子而适应地域环境的。

doi: https://doi.org/10.1186/s13059-018-1444-y

Journal: Genome Biology

Published online: 04 June, 2018