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

人们普遍认为，过去的环境条件的变化加上全基因组复制驱动了辐射，导致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调查的适应价值的分歧，在属萝卜果实和繁殖体架构的空间扩散模式，发芽同步，和模式的遗传多样性内和种群之间。萝卜属是一个地中海属，包括两个密切相关的异地野生一年生植物，R。raphanistrum和R. pugioniformis和栽培R.大蒜前两种原产于地中海东部，在果实形态和传播能力上存在差异，表明单种子单位的R。raphanistrum和R. pugioniformis在其特定的栖息地适应。因此，我们假设，在其原生范围内，长距离风传播在R。raphanistrum的近距离扩散可以解释其在沿着相似的生境中的广泛分布，而在R. pugioniformis确保在异质山区环境中保持在安全的地点进行幼苗建立。因此，萝卜属提供了一个机会，调查和发展一个小属的果实结构和传播机制的进化过程模型。我们建议对以色列和巴勒斯坦权力机构的两个野生物种进行详细的人口调查，例如人口内的空间安排，分布模式，以及生物，土壤和气候因素的评估。将在有限场地测试长距离和短距离的扩散。此外，将研究果实和种子形态以及果实解剖学，并将对包在果皮中的种子与裸种子进行短期和长期发芽试验以及寿命试验。基于种群的阈值模型将被用来解释生态生理调节种子休眠/发芽的环境。在这方面，我们假设萌发的R。rapanistrum在长时间吸胀后发生休眠，而R. pugioniformis仅在果皮因微生物活性或磨损而分解后释放。随着微卫星的使用，我们的目标也是了解栖息地和扩散策略的差异如何影响这些物种的种群内和种群间的遗传变异。我们的项目的结果将提供深入了解适应过程中的年度紫茎泽兰，我们希望，这一跨学科的研究将刺激以色列和巴勒斯坦学生加入这一研究领域。

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.