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: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=566691
• 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.

尽管我们对开花植物形态的多样性非常着迷，但我们对这种变化是如何产生的理解有限。最后，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。我的研究目标是阐明两个重要性状的变异机制：果实结构和花形。果实发育遗传学和进化的详细知识是必不可少的，因为种子传播是植物适应性的关键组成部分。此外，作物的扩散和控制转基因作物系统中的基因流动，以及自然生态系统中引进物种的日益流行，都需要更全面地了解不同类型的种子包装是如何起源的。尽管存在这种相关性，但很少有关于果实的进化发育研究，相反，大多数研究都集中在植物的另一个重要生态特征-花上。显然，花性状对传粉者的相互作用很重要，但我们对影响传粉者行为的遗传基础的认识还存在明显的差距。我集中在两个群体，表现出这些特征的变化，并代表示范系统来调查水果和花卉的进化。在芥菜科（芸苔科）中有一个被称为芸苔科的群体，它很重要，因为它包括作物物种（例如，油菜，西兰花），因为果实通常是分节的，这一特性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，这导致了一个基本问题，即在独立的进化事件中是否同样的遗传途径被招募。与它的姐妹科芸苔科不同，铁线蕨科的成员有许多不同类型的花，便于对传粉者的重要特征进行检查。我们之前的调查揭示了这一群体的一个不同的，但同样迷人的模式。相似的成熟花有两种不同的发育轨迹。因此，我们可以解决另一个重要的问题：这两种模式是否反映了可变的遗传基础？由于这两个类群都与遗传植物模式拟南芥密切相关，并且由于两个家族的丰富基因组资源正在建立，因此遗传学研究得到了极大的便利。在这个提案中，我采取了一个综合的方法，融合了多个领域，将导致我们对植物进化的理解有实质性的进步。首先，我的小组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态是如何实现的基本数据，这反过来又导致了什么样的基因可能负责形态差异的假设，当结合来自模式物种的遗传知识时。当我们结合物种之间的关系时，我们就能全面了解这些谱系的特征是如何随着时间的推移而变化的。将花费大量的精力来确定感兴趣的基因何时何地表达。这些研究已被证明对将特定形态与基因表达模式联系起来是非常有价值的，从而为了解遗传途径如何改变以产生形态创新提供了见解。也就是说，不同物种的不同形态表达模式表明，基因可能在产生观察到的变异中起作用。最后，我的项目将通过直接测试这些基因如何在我们的焦点植物中发挥作用的实验来超越相关性，这代表了进化研究中经常缺乏的关键数据。