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，以及导致它们发展的信号是如何在植物的不同组织和器官中整合的。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。许多雏菊品种会开出两种花。雏菊头状花序的外部（“头状花序”）是两侧对称的花朵，其中一些花瓣没有，一些融合成一个长带状结构（如果雏菊真的是一朵简单的花，你会认为这些“舌状花序”是花瓣的结构）。里面是螺旋状的径向对称的小花，每朵花有5个小花瓣。整个花序合在一起就像一朵大花。然而，有些雏菊甚至更复杂。南非的白花雏菊（Gorteria diffusa）在它的一些外部花朵上制造斑点，这些斑点模仿了主要传粉者苍蝇。雄性苍蝇被骗以为这些斑点是雌性苍蝇，它们会到雏菊上寻找配偶，甚至试图与这些斑点交配。为了使这个系统起作用，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发育信号，有三种方式，我们将在这个项目中探索。首先，这些斑点必须只定位在外部花朵的一个子集上，而且这个位置在外观上必须是令人信服的随机的。我们将使用多种方法，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，以探索决定哪些外部花产生斑点的信号。其次，这些斑点必须生长在舌舌上，舌舌实际上是由4个融合的花瓣组成的。外面的两个花瓣必须有匹配的镜像斑点边缘，它们通过两个内部花瓣无缝地连接到斑点中心。我们将使用激光显微解剖来了解这种发育整合是如何跨器官边界控制的。第三，这个斑点是由多种细胞类型组成的，每一种细胞类型都必须正确地相互定位。我们将使用分子生物学方法来确定指定斑点发育和协调这些细胞类型生产的主要调节因子。综合起来，我们的数据将为一个非常复杂的发育问题提供令人兴奋的见解，同时也揭示了一个极不寻常的授粉系统。

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.