Fruit evolution and adaptation to Mediterranean habitats in Raphanus (Brassicaceae)

萝卜（十字花科）的果实进化和对地中海栖息地的适应

• 批准号: 288490669
• 负责人: Professor Dr. Klaus Mummenhoff
• 金额: --
• 依托单位: W.K. Kellogg Biological Station
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/288490669?language=en
• 关键词: Fruit; evolution; adaptation; Mediterranean; habitats

It is widely accepted that past changes in environmental conditions plus whole-genome duplications have driven radiation of Brassicaceae, resulting in novel adaptive morphological and physiological traits. Here we suggest taking an interdisciplinary approach to investigate the adaptive value of the divergence in fruit and diaspore architecture in the genus Raphanus in respect to spatial dispersal patterns, germination synchronization, and patterns of genetic diversity within and among populations. Raphanus is a Mediterranean genus comprising two closely related allopatric wild annuals, R. raphanistrum and R. pugioniformis and the cultivated R. sativus. The first two are native to the East Mediterranean and differ in fruit morphology and dispersal ability, suggesting that single-seeded units of R. raphanistrum and the heavy multi-seeded diaspores of R. pugioniformis are adaptive in their specific habitats. Accordingly, we hypothesize that in their native range , long-distance wind dispersal in R. raphanistrum, can explain its wide distribution along similar homogenous habitats, while short- distance dispersal in R. pugioniformis ensures remaining in safe sites for seedling establishment in heterogeneous mountainous environments. Thus, Raphanus provides an opportunity to investigate and develop a model of evolutionary processes in fruit architecture and dispersal mechanisms in a small genus. We suggest conducting a detailed population survey of each of the two wild species in Israel and the Palestinian Authority, e.g. spatial arrangements within populations, distribution patterns , and assessment of biotic, edaphic and climatic factors. Dispersal over long and short distances will be tested in confined sites. Furthermore, fruit and seed morphology, and fruit anatomy will be investigated, and short- and long- term germination trials, as well as longevity tests will be set on seeds enclosed in the pericarp vs. bare seeds. Population-based threshold models will be used to explain eco-physiological regulation of seed dormancy /germination by the environment. In this respect we hypothesize that germination of R. raphanistrum occurs upon long imbibition, while pericarp-mediated mechanical dormancy of R. pugioniformis is released only after decomposition of the pericarp by microbial activity or abrasion. With the use of microsatellites we aim also to understand how the differences in habitat and dispersal strategy affect genetic variation within and among populations of these species. The results of our project will provide insight into adaptive processes in annual Brassicaceae and we expect that this interdisciplinary study will stimulate Israeli and Palestinian students to join this research area.

人们普遍认为，过去环境条件的变化加上全基因组复制驱动了十字花科的辐射，从而产生了新的适应性形态和生理特征。在这里，我们建议采取跨学科的方法来研究萝卜属果实和水硬铝石结构差异在空间扩散模式、发芽同步以及种群内部和种群间遗传多样性模式方面的适应性价值。莱菔属（Raphanus）是一个地中海属，由两种密切相关的异域野生一年生植物（R. raphanistrum 和 R. pugioniformis）以及栽培的 R. sativus 组成。前两种原产于东地中海，果实形态和传播能力不同，表明 R. raphanistrum 的单种子单位和 R. pugioniformis 的重多种子水硬铝石能够适应其特定的栖息地。因此，我们假设，在其原生地，萝卜的长距离风传播可以解释其在相似的同质生境中的广泛分布，而萝卜的短距离传播确保了在异质山区环境中幼苗在安全的地方建立。因此，Raphanus 提供了一个研究和开发小属果实结构和传播机制进化过程模型的机会。我们建议对以色列和巴勒斯坦权力机构的两种野生物种进行详细的种群调查，例如。种群内的空间排列、分布模式以及生物、土壤和气候因素的评估。长距离和短距离的传播将在密闭地点进行测试。此外，还将研究果实和种子形态以及果实解剖学，并对包在果皮中的种子与裸露种子进行短期和长期发芽试验以及寿命测试。基于群体的阈值模型将用于解释环境对种子休眠/发芽的生态生理调节。在这方面，我们假设萝卜的萌发发生在长时间的吸胀作用下，而萝卜的果皮介导的机械休眠只有在果皮被微生物活动或磨损分解后才被释放。通过使用微卫星，我们还旨在了解栖息地和扩散策略的差异如何影响这些物种种群内部和种群之间的遗传变异。我们项目的结果将提供对一年生十字花科植物适应性过程的深入了解，我们预计这项跨学科研究将刺激以色列和巴勒斯坦学生加入这一研究领域。