Evolutionary developmental biology of fruits and flowers in Brassicales

芸苔目果实和花的进化发育生物学

• 批准号: RGPIN-2014-04705
• 负责人: Hall, Jocelyn
• 金额: $ 1.89万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=630212
• 关键词: Evolutionary; developmental; biology; fruits; flowers

Despite our fascination with the diversity of forms observed in flowering plants, our understanding of how this variation has arisen is limited. Ultimately, we would like to know how changes in gene regulation have lead to morphological differences – a key question in biology. The goal of my research is to elucidate mechanisms underlying variation in two important traits: fruit structure and floral form. Detailed knowledge of fruit developmental genetics and evolution is essential because seed dispersal represents a key component of plant fitness. Moreover, the dispersal of crop plants and controlling the gene flow in genetically modified crop systems, and the increasing prevalence of introduced species in natural ecosystems necessitate a more complete picture of how different types of seed packaging have originated. Despite this relevance, there are few evolutionary developmental studies on fruits, instead most studies focus on another ecologically important feature of plants – the flower. Floral traits are clearly important for pollinator interactions, yet there is a notable gap in our knowledge of the genetic basis of features that influence pollinator behavior. I focus on two groups that exhibit variation in these traits and that represent exemplary systems to investigate fruit and floral evolution. A group within the mustard family (Brassicaceae), called the Brassiceae, is important because it includes crop species (e.g., canola, broccoli) and because the fruits are often segmented, a trait that dramatically alters how their seeds are dispersed. This complex structure has evolved multiple times, leading to the fundamental question of whether the same genetic pathway has been recruited similarly in independent evolutionary events. Unlike its sister family Brassicaceae, members of Cleomaceae have many different types of flowers, facilitating the examination of features important for pollinators. Our previous investigations unveiled a different, but no less fascinating, pattern in this group. Similar mature flowers have two distinct developmental trajectories. Thus, we can address another important question: do these two patterns reflect variable genetic bases? Genetic studies are greatly facilitated because these two groups are both closely related to the genetic plant model, Arabidopsis, and because a wealth of genomic resources is being built in both families.In this proposal, I take a comprehensive approach that fuses multiple fields and will lead to substantial advancements in our understanding of plant evolution. First, my group will conduct detailed developmental studies on a range of species. This traditional approach provides essential data on how the mature form is achieved, which in turn leads to hypotheses on what genes may be responsible for morphological differences when combined with genetic knowledge from model species. A thorough picture of how traits have changed through time in these lineages emerges when we incorporate information about how species are related to one another. Substantial effort will be spent determining when and where genes of interest are expressed. These studies have been shown to be immensely valuable for correlating a particular morphology with a gene expression pattern, thus providing insight into how genetic pathways may be altered to generate morphological innovations. That is, different expression patterns across species with morphological differences suggest that gene may have a role in generating the observed variation. Finally, my program will move beyond correlation by conducting experiments that directly test how these genes function in our focal plants, which represent critical data often lacking in evolutionary studies.

尽管我们着迷于在开花植物中观察到的形式的多样性，但我们对这种变异是如何产生的理解是有限的。最终，我们想知道基因调控的变化是如何导致形态差异的--这是生物学中的一个关键问题。我的研究目的是阐明两个重要性状的潜在变异机制：果实结构和花形。对果实发育、遗传学和进化的详细了解是至关重要的，因为种子传播是植物适合性的关键组成部分。此外，作物在转基因作物系统中的扩散和基因流动的控制，以及自然生态系统中引进物种的日益普遍，需要更全面地了解不同类型的种子包装是如何起源的。尽管有这种相关性，但很少有关于水果的进化发育研究，相反，大多数研究集中在植物的另一个重要生态特征--花。花的性状显然对传粉者的相互作用很重要，但我们对影响传粉者行为的特征的遗传基础的了解存在着显著的差距。我把重点放在两个组，它们在这些特征上表现出变异，并代表了研究水果和花朵进化的示范系统。十字花科(Brassicaceae)中的一个类群很重要，因为它包括农作物种类(如油菜、花椰菜)，而且果实通常是分段的，这一特征极大地改变了它们种子的传播方式。这种复杂的结构已经进化了多次，这导致了一个根本的问题，即在独立的进化事件中，是否以类似的方式招募了相同的遗传途径。与其姊妹科十字花科不同，蜡梅科的成员有许多不同类型的花，这有助于检查对传粉者重要的特征。我们之前的调查揭示了这一群体中不同的、但同样令人着迷的模式。相似的成熟花有两种截然不同的发育轨迹。因此，我们可以回答另一个重要的问题：这两种模式是否反映了不同的遗传基础？因为这两个群体都与遗传植物模式拟南芥密切相关，而且两个家族都建立了丰富的基因组资源，所以遗传学研究得到了极大的便利。在这个建议中，我采取了一种综合的方法，融合了多个领域，将导致我们对植物进化的理解取得实质性进展。首先，我的团队将对一系列物种进行详细的发育研究。这种传统的方法提供了关于成熟形式如何实现的基本数据，这反过来又导致了当与模式物种的遗传知识相结合时，哪些基因可能导致形态差异的假设。当我们结合物种如何相互关联的信息时，就会出现这些谱系中特征如何随着时间的推移而变化的全面图景。将花费大量的努力来确定感兴趣的基因何时何地表达。这些研究被证明在将特定的形态与基因表达模式相关联方面具有极大的价值，从而为如何改变遗传途径以产生形态创新提供了洞察。也就是说，不同物种之间不同的表达模式与形态上的差异表明，基因可能在产生所观察到的变异中起作用。最后，我的计划将超越相关性，进行实验，直接测试这些基因在我们的焦点植物中如何发挥作用，这些植物代表着进化研究中经常缺乏的关键数据。