Controlled buckling as a mechanism to regulate cuticle patterning in plants

植物的外表面覆盖着一层薄薄的防水材料，称为角质层。当空气干燥时，角质层保护植物免受脱水，还保护植物的脆弱组织免受昆虫和其他动物的破坏，以及细菌和真菌等病原体的入侵。拥有角质层对于陆地上所有植物的生存是绝对必要的，而角质层的进化是植物生命最初迁移到陆地上的关键一步，始于海洋。我们对我们在植物角质层表面发现的图案感兴趣。这些图案是由角质层中的脊状、皱纹或波浪形成的。它们看起来可能是随机的，也可能遵循非常有组织的安排，比如一组长线或星形。它们也可能不存在，提供完全光滑的角质层。所有这些不同的角质层图案都会影响植物与周围世界相互作用的方式，这取决于图案的类型和形成它的器官。例如，花瓣角质层上的长脊，如果以规则的方式组织起来，可能会干扰到达植物表面的光线，并产生彩虹效果。对于吸引传粉者来说，这些对花来说是很重要的。另一个不同的例子是在一些树叶上发现的更大规模的脊状结构，这使得树叶表面对于脚上贴着粘性垫子的昆虫来说很滑。因此，这些植物被保护起来，不受一些本来会吃掉它们的甲虫的伤害。角质层图案也会影响植物表面的润湿性，而最不容易润湿的植物之一--神圣莲花--为设计涂料和其他表面涂层提供了灵感(广为人知的“荷花效应”)。没有人知道这些不同的图案是如何在植物表面形成的，但我们的初步数据表明，它们是由于植物细胞生长时角质层材料的弯曲而产生的。我们已经开发了一个模型，该模型表明，屈曲力的产生是因为植物细胞在一个方向上比在另一个方向上生长得更多，这会拉伸和压缩顶部的角质层。我们的模型表明，只有当角质层具有合适的硬度时，才会发生屈曲，这将是角质层详细化学组成的结果。该模型表明，我们可以认为植物表面的图案是由于植物细胞及其角质层的突现特性--如果细胞生长、角质层化学和角质层生产以特定的方式结合在一起，那么就会发生弯曲，形成图案。在这个建议中，我们想测试我们的模型，以详细了解角质层图案是如何形成的。我们认为，这种理解将在一系列方面发挥重要作用，为生产具有不同作用的人造表面提供灵感，建议通过操纵植物与环境的相互作用来提高作物产量的方法，甚至通过更详细地解释植物如何与环境相互作用来为生物多样性和保护工作提供投入。为了测试我们的模型，我们将使用一系列不同的方法来改变或干扰植物细胞的生长、角质层产生的数量和角质层的化学成分。然后我们将分析这些变化是如何影响角质层屈曲和图案形成的。我们的许多方法将依赖于改变控制细胞生长和角质层生产或化学的基因的活性，但我们也将使用植物组织的物理拉伸和药物(化学)干扰细胞生长，以提供广泛的不同角质层模式。我们的数据将反馈到我们的模型中，并对这一重要的生物过程提供强有力的理解。

The outer surfaces of plants are covered in a thin layer of a water-repellent material called the cuticle. The cuticle protects the plant from dehydration when the air is dry, and it also protects the plant's delicate tissues from damage by insects and other animals and from invasion by pathogens such as bacteria and fungi. Having a cuticle is absolutely essential for the survival of all plants on land, and the evolution of the cuticle was a key step when plant life first moved onto the land, having begun in the sea.We are interested in the patterns that we find on the surface of plant cuticles. These patterns are formed from ridges, wrinkles or waves in the cuticular material. They can appear random, or can follow very organised arrangements such as sets of long lines or star shapes. They may also be absent, giving an entirely smooth cuticle. All of these different cuticle patterns affect the way that the plant interacts with the world around it, depending on the type of pattern and the organ on which it forms. For example, long ridges on the petal cuticle, if organised in a regular way, can interfere with light arriving at the plant surface and produce iridescent effects. These can be important on flowers to attract pollinators. A different example is the larger scale ridges found on some leaves, which make the leaf surface slippery for insects that grip with adhesive pads on their feet. As a result, these plants are protected from some of the beetles that would otherwise eat them. Cuticle patterns can also affect the wettability of the plant surface, and one of the least wettable plants, the Sacred Lotus, has provided the inspiration for the design of paints and other surface coatings that shed water (widely known as the "Lotus effect").Nobody knows how these different patterns form on the plant surface, but our preliminary data suggest that they are produced by buckling of the cuticular material as the plant cells grow. We have developed a model which suggests that buckling forces arise because the plant cells grow more in one direction than another, and this stretches and compresses the cuticle on top. Our model suggests that buckling can only occur if the cuticle is of the right stiffness, which will be a result of the detailed chemical make-up of the cuticle. The model suggests that we can think of the patterns on the plant surface as a result of the emergent properties of the plant cells and their cuticle - if cell growth, cuticle chemistry and cuticle production come together in a specific way, then buckling will occur and patterns will be formed.In this proposal we would like to test our model, to gain a detailed understanding of how cuticle patterns form. We believe that this understanding will be important in a range of ways, providing inspiration for the production of artificial surfaces with different roles, suggesting ways of improving crop yield by manipulating the plant's interaction with the environment, and even providing input into biodiversity and conservation work by explaining how plants interact with their environments in more detail. To test our model we will use a range of different approaches to change or perturb the growth of plant cells, the amount of cuticle produced, and the chemistry of cuticle. We will then analyse how these changes influence cuticle buckling and pattern formation. Many of our approaches will rely on altering the activity of the genes controlling cell growth and cuticle production or chemistry, but we will also use physical stretching of plant tissues and pharmacological (chemical) disruption of cell growth to give a wide range of different cuticle patterns. Our data will feed back into our model and provide a strong understanding of this important biological process.