The mechanics of pollinator attraction: development and function of floral diffraction gratings

模式形成是所有多细胞生物发育的关键。虽然生物学家传统上关注于主动控制的模式系统，但许多生物模式是由物理力作用于具有特定化学物质的材料而产生的新兴现象。这是生物的本性所不可避免的结果。虽然遗传程序和发育途径似乎具有巨大的力量来塑造形式，但它们只能在由化学性质定义的材料和由物理力量主导的世界中这样做。所有有生命的物质都是由分子组成的，根据分子的类型、频率和组织，这些分子会赋予组织特定的物质特性。所有生物在生长发育过程中都受到物理力量的影响。从这个角度来看，经典的发育生物学不能解释所有的模式就不足为奇了。直到最近，机械涌现模式的形成才受到相对较少的关注，但现在正在各种系统，器官和组织水平上进行探索。机械涌现模式的一个例子是在植物和动物身上都能发现的表皮褶皱。规律排列的皱纹会影响组织的光学特性。例如，芙蓉花瓣上细长的皱纹就像衍射光栅一样，产生了结构颜色，可以帮助大黄蜂更快地找到目标。我们对植物或动物的任何组织在发育过程中如何形成褶皱图案知之甚少，比如三叶草花瓣衍射光栅。花衍射光栅很少发生，但已经进化了多次，表明它们在吸引传粉者方面很重要。在行为研究中被用作传粉媒介的大黄蜂，发现带有复制花瓣衍射光栅的人造花朵比没有花瓣衍射光栅的对照更快。然而，对于这些人造表面的实验是否真的复制了自然条件，以及因此花衍射光栅是否真的对传粉者的吸引力或植物的适应性有任何影响，科学界存在相当大的争论。在这个项目中，我们将讨论芙蓉衍射光栅的发展和它的功能。我们已经开发了一个机械模型，通过作用在组织上的物理力来解释光栅的发展，我们已经开发了工具来测试这个模型，使用转基因方法来改变植物的组织特性。当我们进行这项测试时，我们将生产出没有衍射光栅的转基因植物，或者是改变了衍射光栅的形式。我们将在实验室和温室的行为实验中使用这些数据，以充分了解衍射光栅如何影响传粉者的行为。我们的项目将帮助科学家了解花的形态是如何形成的，以及它们在吸引传粉者方面是如何起作用的。

Pattern formation is key to the development of all multicellular organisms. Although biologists traditionally focus on actively controlled patterning systems, many biological patterns are emergent phenomena arising from physical forces acting on materials with specific chemistries. This is an inevitable consequence of the nature of living organisms. While genetic programmes and developmental pathways appear to have great power to sculpt form, they can only do so with materials defined by their chemical properties and in the context of a world dominated by physical forces. All living material is composed of molecules which, according to their types, frequency and organization, will confer particular material properties on the tissue. And all living organisms are subject to physical forces throughout their growth and development. From this perspective, it is not surprising that classical developmental biology cannot account for all patterns. Mechanically-emergent pattern formation has received relatively little attention, until recently, but is now being explored at a variety of system, organ and tissue levels. One example of a mechanically-emergent pattern is that of epidermal wrinkles, found in both plants and animals. Regular arrays of wrinkles can influence the optical properties of a tissue. For example, elongated rows of wrinkles on the petals of Hibiscus trionum act as a diffraction grating, giving rise to structural colour which can help bumblebees to find targets more quickly. We know very little about how wrinkle patterns, such as the H. trionum petal diffraction grating, form during development, in any tissue in either plants or animals.Floral diffraction gratings occur infrequently, but have evolved multiple times, suggesting that they are important in pollinator attraction. Bumblebees, used as model pollinators in behavioural studies, find artificial flowers with replica petal diffraction gratings more quickly than controls without them. However, there is considerable debate in the scientific community about whether these experiments with artificial surfaces really replicate natural conditions, and therefore whether floral diffraction gratings really have any impact either on pollinator attraction or on plant fitness.In this project we will address both the development of the Hibiscus trionum diffraction grating and its function. We have developed a mechanical model which explains the development of the grating through physical forces acting on the tissue, and we have developed the tools to test this model using transgenic approaches to change the plant's tissue properties. As we do this testing, we will produce transgenic plants which lack the diffraction grating, or have altered forms of it. We will use these in behavioural experiments in the lab and in glasshouses to understand fully how the diffraction grating affects pollinator behaviour. Our project will help scientists to understand how flower forms develop, and also how they function in pollinator attraction.