Genetic basis of interspecific differences in resistance to drought stress of the sister species Arabidopsis halleri and A. lyrata

水资源限制是世界范围内限制作物产量的最重要因素之一。为了设计可持续的策略来优化作物的抗旱性，可以从比较不同生态的自然物种中学到很多东西。事实上，在它们的自然栖息地，物种已经优化了它们的策略，以在不损害整体植物适应性的情况下在干旱中生存。我们实验室之前的工作表明，两种A. lyrata和A. halleri在生态环境以及在对降水缺失的响应中激活回避和耐受机制的能力方面存在差异。我们已经证明，耐旱的A. lyrata和干旱敏感的A. halleri都在很大程度上重塑了它们的转录组。我们进一步收集的证据表明，这两个物种在组成和干旱响应代谢物水平上都存在差异。我们现在必须在物种之间的表型、代谢或转录差异与植物抵抗干旱胁迫的实际能力之间建立功能遗传联系。为此，我们发展了种间回交种群。我们将利用这些种群来绘制干旱反应种间差异的遗传基础。我们将进一步使用群体分离方法来确定基因表达和代谢修饰与干旱胁迫下存活率的提高有关。这将有助于区分表现出压力状态的应激反应基因与那些积极有助于恢复体内平衡和促进抗旱能力的基因。这将进一步验证先前报道的作为多基因选择目标的功能所起的作用。最后，我们提出将这一种间种群的遗传变异分离与全球生态多样性描述联系起来，这将有助于将已知的拟南芥属知识转移到其他与生态或农业相关的物种和属中。从长远来看，我们相信在这项研究中获得的知识有可能为设计可持续的策略来提高作物的耐旱性带来开创性的信息。

Water limitation is one of the most important factors limiting crop productivity worldwide. To design sustainable strategies to optimize crop resistance to drought, much can be learned from comparing natural species with diverse ecologies. Indeed, in their natural habitat, species have optimized their strategies to survive drought without compromising overall plant fitness. Previous work in our laboratory has shown that the two species A. lyrata and A. halleri differ in their ecology as well as in their ability to activate avoidance and tolerance mechanisms in response to missing precipitation. We have shown that both the drought-tolerant A. lyrata and the drought-sensitive A. halleri have considerably reshaped their transcriptome. We further collected evidence that the two species differ in both constitutive and drought responsive metabolite levels. We now have to establish functional genetic links between phenotypic, metabolic or transcriptional differences between species and the actual ability of plants to withstand drought stress. To this end, we have developed interspecific back-cross populations. We will leverage these populations to map the genetic basis of interspecific differences in drought reactions. We will further use a bulk-segregant approach to determine gene expression and metabolic modifications associating with improved survival to drought stress. It will help differentiate stress-responsive genes that manifest a state of stress from those that actively contribute to restore homeostasis and promote resistance to drought. This will further validate the role played by functions that have been previously reported to be the target of polygenic selection. Finally, we propose to relate the genetic variation segregating in this interspecific population to global descriptors of ecological diversity, which should help transfer knowledge from the well-known Arabidopsis genus to other species and genera of major ecological or agricultural relevance. On the long term, we believe that the knowledge gained in this study has the potential to bring seminal information for the design of sustainable strategies for improving drought tolerance in crops.