Evolutionary developmental biology of fruits and flowers in Brassicales

尽管我们对在开花植物中观察到的形式多样性很着迷，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，作物的传播和控制转基因作物系统中的基因流动，以及引进物种在自然生态系统中的日益普遍，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，大多数研究都集中在植物的另一个重要生态特征-花。花的性状显然是重要的传粉相互作用，但有一个显着的差距，我们的知识的遗传基础的功能，影响传粉行为。我专注于两组表现出这些性状的变化，并代表典型的系统，以调查水果和花卉的进化。芥菜科（芥菜科）中的一个组，称为芥菜科，是重要的，因为它包括作物物种（例如，油菜、西兰花），而且因为果实通常是分节的，这一特性极大地改变了种子的传播方式。这种复杂的结构已经进化了多次，导致了一个基本问题，即在独立的进化事件中，是否有相同的遗传途径被相似地招募。与它的姐妹科苦菜科不同，苦菜科的成员有许多不同类型的花，便于检查对传粉者重要的特征。我们之前的调查揭示了一个不同的，但同样迷人的，在这个群体中的模式。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植物的遗传模型拟南芥（Arabidopsis）密切相关，而且这两个类群都拥有丰富的基因组资源，因此对植物的遗传学研究有着极大的便利性。在本研究中，我将采取一种融合多个领域的综合方法，这将使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式是如何实现的基本数据，这反过来又导致了关于什么基因可能与模式物种的遗传知识相结合时负责形态差异的假设。当我们把物种之间的相关性信息结合起来时，一幅关于这些谱系特征如何随时间变化的完整图景就出现了。将花费大量的努力来确定感兴趣的基因何时何地表达。这些研究已被证明是非常有价值的相关特定的形态与基因表达模式，从而提供洞察遗传途径如何可能被改变，以产生形态创新。也就是说，具有形态差异的物种之间的不同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，我的计划将超越相关性，通过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，这代表了进化研究中经常缺乏的关键数据。

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.