Modelling growth and gene regulation in floral organs

生物是由不同的器官组成的，其形状和功能由基因决定。几十年的遗传实验已经揭示了许多控制器官发育的关键基因，但我们仍然不知道这些基因如何共同作用，以指导和组织成千上万个细胞的行为，这些细胞在每种器官类型的发育过程中繁殖并获得专门的作用。我们不理解器官发育的一个原因是，尽管我们可以单独描述基因之间和细胞之间的相互作用，但基因和细胞的集体行为太复杂，无法直观地掌握。因此，需要计算机建模来描述和预测发育过程中基因和细胞的集体行为。另一个局限性是，我们对器官生长和支撑器官生长的细胞活动的测量过于粗糙，无法用于将基因活动和生长联系起来的计算机模型。本项目旨在通过研究花器官（萼片和花瓣）的发育来促进我们对基因网络如何控制器官生长的理解。选择花器官有几个原因：-它们的形状是独特的，但相对简单，它们的生长仅基于细胞分裂和细胞扩张，细胞之间没有相对运动，就像在动物发育中经常看到的那样。- 许多控制花器官发育的基因已被深入研究，包括控制花器官形成类型、器官数量、形状和边界的基因。- 近年来，法国和英国的实验室已经开发出可视化和精确测量植物器官生长的方法，并在计算机中模拟它。这些实验室已经开发出不同的方法来研究器官生长的早期阶段，细胞细节，或后期阶段，捕捉更大的生长特征。我们将联合收割机结合现有的计算机模拟植物器官生长的专业知识与我们的调控基因的知识，产生计算机模型，模拟和预测关键基因和花器官生长之间的相互作用。为此，我们将：- 在器官形成的早期阶段直接观察和记录细胞行为-标记小细胞群，并在器官发育的较长时期内追踪它们的增殖和生长-使用这些信息构建花器官生长的计算机模拟-收集关于关键调控基因在花器官发育期间如何相互作用的信息，并建立这些相互作用的计算机模型。- 将调控基因的作用整合到生长模型中。为了做到这一点，我们将使用我们可以操纵关键调控基因的植物来改变器官的身份，从萼片到花瓣，在不同的发育阶段，或在器官的不同区域。我们还将跟踪以关键调控基因表达为标志的细胞的行为。- 使用计算机模型来预测在特定扰动（例如调节基因的表达改变）后生长会发生什么，并通过实验测试这些预测（使用具有突变或调节基因功能改变的植物）。

Living beings are made of different organs whose shape and function are determined by genes. Decades of genetic experiments have revealed many key genes that control organ development, but we still do not understand how these genes act together to direct and organise the behaviour of the thousands of cells that multiply and acquire specialised roles during the development of each organ type. One reason why we do not understand organ development is that although we can describe the interactions between genes and between cells individually, the collective behaviour of genes and cells is too complex to grasp intuitively. Therefore, computer modelling will be required to describe and predict the collective behaviour of genes and cells during development. Another limitation is that our measurements of organ growth and of the cellular activities that underpin it are too crude to use in computer models relating gene activity and growth. The present project aims to advance our understanding of how networks of genes control organ growth, by studying the development of floral organs (sepals and petals). There are several reasons for choosing floral organs: - Their shapes are distinctive but relatively simple and their growth is based only on cell division and cell expansion, with no movement of cells relative to each other, as seen often in animal development. - Many genes controlling floral organ development have been intensively studied, including genes that control the type of floral organ formed, the number, shape and boundaries of organs. - In recent years, laboratories in France and in the UK have developed methods to visualise and measure precisely the growth of plant organs and simulate it in the computer. These labs have developed different approaches to study the very early stages of organ growth, with cellular detail, or later stages, capturing larger features of growth. We will combine the existing expertise on computer modelling of plant organ growth with our knowledge of regulatory genes to produce computer models that simulate and predict the interactions between key genes and growth of floral organs. To achieve this, we will: - Directly observe and record cell behaviour at early stages of organ formation - Mark small groups of cells and trace their proliferation and growth during longer periods of organ development - Use this information to construct computer simulations of floral organ growth - Collect information on how key regulatory genes interact with each other during floral organ development and build computer models of these interactions. - Integrate the action of regulatory genes into the growth models. To do this, we will use plants in which we can manipulate key regulatory genes to change the identity of organs from sepals to petals at different stages of development, or in different regions of the organs. We will also follow the behaviour of cells that are marked by expression of key regulatory genes. - Use the computer models to predict what happens to growth after specific perturbations (such as altered expression of regulatory genes) and test experimentally these predictions (using plants with mutation or altered function of regulatory genes).