V-Morph_Unravelling how the mechanical regulation of local variability shapes reproducible plant organs

农产品的重大损失是由于气候日益多变以及作物易受病原体攻击或极端环境条件的影响造成的。此外，农用工业和最终市场往往需要高度同质的作物。这就提出了韧性的问题：如何生产出健壮和同质的作物？在这里，我们讨论了发育生物学中相应的关键问题：面对内部和外部的干扰，器官如何形成大小和形状一致的形状？我们已经组建了一个跨学科的团队来解决高度可变的细胞和强大的器官之间的明显二分法。以前的研究集中在突变和影响器官整体大小和形状的条件上，从而发现了大量的调节因子。然而，大多数分析只考虑了细胞的平均行为，而忽略了局部异质性和随机变异。在这里，我们采用正交法：我们筛选器官大小或形状变异性增强的突变。植物会开很多花，这让我们能够检测到单个有机体内的可变性。我们选择了最外层的叶状花器官--背面的萼片，因为它便于成像和显微操作：从原基到成熟器官的器官发生的全过程可以用共聚焦显微镜观察到。在我们以前工作的基础上，我们认为组织力学和机械传感是器官变异的关键调节因素，因为形态发生直接依赖于生长的机械控制，而且机械应力在很大程度上是由器官的大小和形状决定的。我们将在拟南芥中验证这一假设，拟南芥是为了获得遗传和分子资源而选择的。我们的主要目标是(I)考虑生长及其影响因素，在所有尺度上分析萼片形态发生的时空变异性，(Ii)通过在影响细胞壁、植物水力学和机械传感的突变体中进行定向筛选，识别和表征调节变异性的基因，以及(Iii)在生长的力学模型中集成相应的机制，并通过实验测试这些模型，特别是通过对海豹的局部机械和遗传扰动。总体而言，我们的项目解决了发育生物学中的一个中心问题，与食品安全有关，特别是在气候波动增加的背景下。一方面，我们将分离和表征花器官稳健性的分子调节因子。我们将在植物品系中过度表达这些调节子，并检查这些品系是否具有更多同质的器官(例如同质的角果)。另一方面，我们将在植物科学的背景下发展生物物理测量，这可能适用于从水果坚固性到生物材料特性或生物机械弹性的广泛的研发问题。

Significant loss in agricultural products is caused by increasingly variable climate and vulnerability of crops to pathogen attacks or extreme environmental conditions. In addition, the agro-industry and the final market often require highly homogeneous crops. This raises the issue of resilience: How to produce robust and homogeneous crops? Here we address the corresponding key question in developmental biology: How do organs form with consistent sizes and shapes in the face of internal and external perturbations? We have assembled an interdisciplinary team to resolve the apparent dichotomy between highly variable cells and robust organs.Previous research has focused on mutants and conditions that affect the global size and shape of organs, enabling the discovery of a large number of regulators. However, most analyses have considered only average cell behaviours, overlooking local heterogeneity and stochastic variation. Here we adopt an orthogonal approach: We screen for mutants with enhanced variability in organ size or shape. Plants produce many flowers, allowing us to detect variability within an individual organism. We have chosen the abaxial sepal, the outermost leaf-like floral organ, for its accessibility for imaging and micromanipulation: the whole process of organogenesis from a primordium to the mature organ can be observed with a confocal microscope. Variability of sepal size and shape can be assessed within an individual plant.Based on our previous work, we propose that tissue mechanics and mechanosensing are key regulators of organ variability, because morphogenesis directly depends on the mechanical control of growth and because mechanical stress is largely prescribed by organ size and shape. We will test this hypothesis in Arabidopsis thaliana, chosen for the availability of genetic and molecular resources. Our main objectives are (i) to analyse spatial and temporal variability in sepal morphogenesis at all scales, considering growth and its effectors, (ii) to identify and characterise genes that regulate variability, by performing a directed screen among mutants affecting the cell wall, plant hydraulics, and mechanosensing, and (iii) to integrate the corresponding mechanisms in mechanical models of growth and test these models experimentally, notably by local mechanical and genetic perturbations to sepals.Overall, our project addresses a central question in developmental biology and is relevant to food security, especially in the context of increasing climatic fluctuations. On the one hand, we will isolate and characterise molecular regulators of the robustness of flower organs. We will overexpress these regulators in plant lines and examine if these lines have more homogeneous organs (e.g. homogenous siliques). On the other hand, we will develop biophysical measurements in the context of plant sciences, which may apply to a broad range of R&D problems, from fruit firmness to biomaterial properties or biomechanical resilience.