Reaching for the sky: exploring massive convergent evolution towards woodiness in Brassicaceae

伸向天空：探索十字花科向木质化的大规模趋同进化

• 批准号: 418452287
• 负责人: Professor Dr. Klaus Mummenhoff
• 金额: --
• 依托单位: Molecular Biology Institute
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/418452287?language=en
• 关键词: Reaching; sky; exploring; massive; convergent

Woody plants (trees and shrubs) cover 30 percent of the planet's land area and offer crucial ecosystem services, such as buffering climate change by storing carbon from the atmosphere. It is unclear, however, why some plants are woody and others herbaceous. This seemingly simple question intrigued Charles Darwin when he visited oceanic islands in the 1830s, and he used the term ‘insular woodiness’ (later rephrased to the broader term ‘derived woodiness’) for woody flowering plant species that have evolved from herbaceous relatives that in turn originated from ancestrally woody species. To this day, scientists have failed to provide satisfying answers why derived woodiness have occurred hundreds of times during evolutionary history of flowering plants, probably because wood formation is a complex process that can be triggered in different and largely understudied ways. Solving this long-standing question requires an innovative multidisciplinary approach, linking evolutionary and ecological models. The cosmopolitan mustard family (Brassicaceae, 4000 species) serves as an excellent model group to understand wood formation due to the occurrence of many crops and model species, and the remarkable number of evolutionary transitions towards the derived woody growth form. Ten percent of the Brassicaceae species are woody – reaching up to 9m tall – and woodiness has evolved probably more than 100 separate times in contrasting environments on both islands and continents, which is extraordinary for a single family. However, deep phylogenetic relationships within Brassicaceae remain poorly understood, thereby impeding evolutionary questions at the family level. This proposal focuses on three main objectives: (1) accurately assess the number of transitions towards woodiness in Brassicaceae based on a (time-calibrated) family phylogeny using hybridization sequencing of 1000 carefully selected species, (2) test the impact of woodiness as potential driver for species diversification across the 100+ clades including woody Brassicaceae, and (3) determine the correlation between woodiness versus (palaeo)climate and soil variables in these clades. Outcomes of this project will revolutionize our understanding of wood formation, bridge the gap between evolutionary biologists and ecophysiologists, and provide a robust phylogenetic framework that will serve the entire Brassicaceae community for the coming years. Moreover, the proposed work on wood evolution can open up new opportunities for developmental genetists who will be able to search for the key regulatory genes that turn on the wood pathway in many woody-herbaceous sister pairs that are all closely related to Arabidopsis.

木本植物(树木和灌木)覆盖了地球陆地面积的30%，并提供关键的生态系统服务，例如通过储存大气中的碳来缓冲气候变化。然而，目前还不清楚为什么有些植物是木质的，而另一些是草本的。这个看似简单的问题让查尔斯达尔文在19世纪30年代访问海洋岛屿时很感兴趣，他使用了“岛状木质”(后来改称为更广泛的术语“衍生木质”)一词来指代木本开花植物物种，这些植物是从草本植物的近亲进化而来的，而草本植物又起源于祖先的木本植物。直到今天，科学家们还未能提供令人满意的答案，为什么在开花植物的进化史上，衍生的木质会出现数百次，可能是因为木材的形成是一个复杂的过程，可以通过不同的方式触发，而且在很大程度上没有得到充分的研究。解决这个长期存在的问题需要一种创新的多学科方法，将进化模型和生态模型联系起来。世界芥菜科(十字花科，4000种)是理解木材形成的一个很好的模式组，这是由于许多作物和模式物种的出现，以及向衍生的木质生长形式的大量进化过渡。十字花科物种中有10%是木质的--高达9米--在两个岛屿和大陆上截然不同的环境中，木质可能进化了100多次，对于一个家庭来说，这是非同寻常的。然而，十字花科内部深层的系统发育关系仍然鲜为人知，因此阻碍了科水平上的进化问题。这项建议集中于三个主要目标：(1)通过对1000个精心挑选的物种的杂交测序，基于(时间校准的)家族系统发育，准确地评估十字花科向木质转变的数量，(2)测试木质作为包括木本十字花科在内的100多个支系物种多样性的潜在驱动因素的影响，以及(3)确定木质与(古)气候和土壤变量之间的相关性。该项目的成果将彻底改变我们对木材形成的理解，弥合进化生物学家和生态生理学家之间的差距，并提供一个强大的系统发育框架，在未来几年将服务于整个十字花科群落。此外，拟议的木材进化工作可以为发育遗传学家开辟新的机会，他们将能够在许多与拟南芥密切相关的木本-草本姐妹对中寻找开启木材途径的关键调控基因。