Development of an integrated multi-petal pollinator attractant

我们感兴趣的是了解非常复杂的结构是如何形成的，以及导致它们发育的信号如何在植物的不同组织和器官中整合。雏菊是非常复杂的结构。虽然它们可能看起来是简单的花，但仔细观察就会发现它们既不简单，也不是花。雏菊是由许多非常小的花组成的结构，排列在一起，看起来像一朵大花。许多雏菊品种产生两种类型的花。围绕着雏菊头的外部（“头状花序”）是两侧对称的花，其中一些花瓣是缺席的，一些是融合的，形成一个长带形的结构（这些“叶舌”是你会假设的结构，如果雏菊是一个简单的花花瓣）。在这些里面是小的径向对称的花朵，每个有5个微小的花瓣螺旋。整个花序一起工作，模仿一个大花。然而，一些雏菊甚至更复杂。南非雏菊Gorteria diffusa在它的一些外部花朵上产生斑点，这些斑点模仿了主要的传粉者苍蝇。雄蝇被骗以为斑点是雌蝇，它们访问雏菊寻找配偶，甚至试图与斑点交配。为了让这个系统发挥作用，这些斑点必须非常令人信服地模仿雌性果蝇，这需要非常详细的协调和整合三种方式的发育信号，我们将在这个项目中探索。首先，斑点必须只定位在外部花的一个子集上，并且这种定位必须在外观上具有令人信服的随机性。我们将结合多种方法，包括对雏菊发育过程中表达的所有基因进行测序，并比较具有不同斑点模式的品种，以探索决定哪些外层花产生斑点的信号。第二，斑点必须正好穿过叶舌，而叶舌实际上是由4个融合的花瓣形成的。外部2个花瓣必须具有匹配的镜像斑点边缘，其无缝地连接到穿过2个内部花瓣的斑点中心。我们将使用激光显微切割来了解这种发育整合是如何跨越器官边界控制的。第三，斑点由多种细胞类型组成，每种细胞类型必须相互正确定位。我们将使用分子生物学方法来确定指定斑点发展和协调这些细胞类型的生产的主调节器。总之，我们的数据将为一个非常复杂的发展问题提供令人兴奋的见解，同时也揭示了一个非常不寻常的授粉系统。

We are interested in understanding how very complex structures are formed, and how the signals that cause them to develop are integrated across different tissues and organs of a plant.Daisies are very complex structures. While they might appear to be simple flowers, a closer look reveals that they are neither simple, nor flowers. A daisy is a structure composed of many very small flowers, arranged together in a group that looks like one large flower. Many daisy species produce 2 types of flowers. Around the outside of the daisy head (the "capitulum") are bilaterally symmetrical flowers, in which some of the petals are absent and some are fused to make a long strap shaped structure (these "ligules" are the structures that you would assume are the petals if a daisy were really a simple flower). Inside these are spirals of small radially symmetrical flowers which have 5 tiny petals each. The whole inflorescence works together to mimic a single large flower.However, some daisies are even more complex. The South African daisy Gorteria diffusa makes spots on some of its outer flowers, and these mimic the fly that is the main pollinator. Male flies are tricked into thinking the spots are female flies, and they visit the daisies to find mates, even attempting to copulate with the spots. For this system to work, the spots have to be very convincing mimics of female flies, and this requires very detailed coordination and integration of developmental signalling in 3 ways, which we will explore in this project.First, the spots have to be positioned on only a subset of outer flowers, and that positioning has to be convincingly random in appearance. We will use a combination of approaches, including sequencing of all the genes expressed in developing daisies and comparing varieties with different patterns of spots, to explore the signalling that determines which outer flowers produce spots.Second, the spots have to develop right across the ligule, which is actually formed from 4 fused petals. The outer 2 petals must have matching mirror image spot edges, which join seamlessly to the spot centre across the 2 inner petals. We will use laser microdissection to understand how this developmental integration is controlled across organ boundaries.Third, the spot is composed of multiple cell types which must each be positioned correctly with respect to one another. We will use molecular biology approaches to identify the master regulators which specify spot development and coordinate the production of these cell types.Taken together our data will provide exciting insights into a very complex developmental problem, while also shedding light on a highly unusual pollination system.