Mapping the molecular basis of growth form divergence in tropical alpine Arabidopsis thaliana

在高山环境中，在很短的地理距离内可能出现陡峭的温度梯度。这使得海拔梯度成为暴露适应性的遗传和生理基础以允许在恶劣环境中生存的有效系统。在高海拔环境中，有几种特殊的生长形式，包括低矮和匍匐灌木、垫状植物、草丛草和草本莲座丛植物。向矮身材和更紧凑形式的转变在物种中非常普遍，并且被假设为是由于对寒冷温度的抵抗力增加的需要。拟南芥是一个强大的生态模式，因为我们可以应用不同的遗传和分子工具和知识，在这个系统中开发，以确定特定的分子和遗传基础的进化变化。我们已经收集了1000多个A。从海拔2222至4432米，在埃塞俄比亚的8个山脉，包括海拔横断面在其中4个。我们发现高海拔和低海拔的加入之间的增长形式显着的变化，从最高海拔的加入表现出两个表型极端之一：极端侏儒症或匍匐生长习性与斜向性增长。这些表型变化让人想起那些与不同物种的高海拔典型相关的变化。该提案的主要目标是确定负责生长形式转变的遗传变异，并重建埃塞俄比亚Afroalpine A中四个重复品系的进化历史。thaliana. 该项目有以下具体目标：目标1：组装12个正常、矮秆和斜向性种质的代表性基因组，鉴定结构变异，并产生埃塞俄比亚泛基因组参考目标2：利用全基因组关联（GWAS）和重组群体（F2）鉴定生长形式变异的遗传位点，并评估基于生殖适合度的适应证据目标3：利用群体遗传学分析研究与这些生长型转变有关的适应性进化的证据。

In alpine environments steep gradients in temperature can occur over short geographical distances. This makes altitudinal clines effective systems for exposing the genetic and physiological basis for adaptations to allow survival in harsh environments. Several specific growth forms are enriched in high altitude environments, including low-stature and prostrate shrubs, cushion plants, tussock grasses and herbaceous rosette plants. Shifts to low-stature and more compact forms are strikingly common across species and have been hypothesized to result from an increased need for resistance to cold temperatures. Arabidopsis thaliana is a powerful ecological model because we can apply diverse genetic and molecular tools and knowledge developed in this system to identify the specific molecular and genetic bases for evolutionary change. We have collected over 1000 A. thaliana accessions from altitudes ranging from 2222 to 4432 m over eight mountain ranges in Ethiopia, including altitudinal transects across four of these. We find striking variation in growth form between high and lower altitude accessions, with accessions from the highest altitudes exhibiting one of two phenotypic extremes: either extreme dwarfism or a prostrate growth habit with plagiotropic growth. These phenotypic shifts are reminiscent of those classically associated with high altitude across diverse species. The main objective of this proposal is to identify the genetic variants responsible for growth form shifts and reconstruct the evolutionary history of these across four replicate clines in Ethiopian Afroalpine A. thaliana. The project has the following specific aims:Objective 1: To assemble 12 representative genomes of normal, dwarf and plagiotropic accessions, identify structural variants, and produce an Ethiopian pan-genome referenceObjective 2: To identify the genetic loci underlying growth form variation using genome wide association (GWAS) and recombinant populations (F2s) and assess evidence of adaptation based on reproductive fitnessObjective 3: To investigate evidence for adaptive evolution related to these growth form shifts using population genetic Analysis.