Evolution of floral organ reduction

我们的目标是了解不同的物种如何进化出不同的物理特征。有花植物是地球上物种数量最多、多样性最丰富的植物类群，花瓣通过吸引不同的传粉者，在产生这种多样性方面发挥了关键作用。许多植物也可以自己授粉，这对入侵新栖息地的杂草（如多毛芥）有利。这种向自花授粉的过渡可能与花瓣脱落有关，然而，决定花瓣数量的遗传机制以及这些机制在进化过程中如何变化，人们知之甚少，因此是我们研究的重点。我们的研究旨在了解两种芥菜物种，模式生物塔勒水芹（拟南芥）和毛叶水芹（碎米荠）之间花瓣数量变化的遗传变化。这些物种密切相关，易于在实验室中使用，因此遗传和转基因实验可以用来确定使这两个物种看起来彼此不同的机制。塔勒水芹有一个典型的芥末花与四个花瓣，而毛水芹不同的是有较少的花瓣。我们知道，多毛芥基因组的一个区域控制着在该物种中观察到的花瓣数量的大量变异。我们还知道，一个重要的基因控制花瓣发育称为LEAFY映射到这个基因组区域。为了鉴定抑制毛水芹花瓣数的基因，我们通过诱变在基因组中诱导变异，并鉴定了将毛水芹转化为塔勒水芹花瓣数的突变体。鉴定这些植物中的突变基因将告诉我们哪些基因在毛叶水芹中起作用而在塔勒水芹中不起作用。LEAFY调节花瓣发育的一种方式是通过打开APETALA1基因的表达。塔勒水芹中的其他调节因子也会开启这个基因，但在毛叶水芹中没有。我们想知道基因调控的这种差异是否在使这两个物种看起来彼此不同的过程中发挥了作用。在这里，我们将确定是否LEAFY或不同的基因控制的变化，观察到在毛茸茸的芹菜种群。我们还将鉴定出只在多毛芹菜中起作用以减少花瓣数量的基因。在进化过程中产生不同外观物种的许多遗传变化是由基因调节方式的变化引起的，我们将测试这两种芥菜物种中的APETALA1基因是否如此。因此，物种特异性的差异，花瓣数之间的毛茸茸的芹菜和塔勒，和自然的变化，在这个性状之间的毛茸茸的芹菜人口在世界各地，提供了一个令人兴奋的实验平台，以跟踪进化，从特定的变化，基因调控，通过改变形态的性质。另一组被称为musicas的是显着的包含比任何其他植物属更重要的农业和园艺作物。因此，了解芥菜多样性的遗传基础是培育21世纪世纪作物的重要组成部分。

We aim to understand how different species evolve different physical features. Flowering plants have the greatest species number and diversity of any plant group on earth and petals played a critical role in generating this diversity by attracting different pollinators. Many plants can also pollinate themselves and this can be advantageous for weeds like hairy bittercress that invade new habitats. This transition to self-pollination can be associated with petal loss, however, the genetic mechanisms that determine petal number, and how these have varied during evolution, are poorly understood and are hence the focus of our research. Our research aims to understand the genetic changes that underlie changes in petal number between two mustard species, the model organism thale cress (Arabidopsis thaliana) and hairy bittercress (Cardamine hirsuta). These species are closely related and easy to work with in the lab, so genetic and transgenic experiments can be used to identify mechanisms that make these two species look different from each other. Thale cress has a typical mustard flower with four petals while hairy bittercress differs by having fewer petals. We know that one region of the hairy bittercress genome controls a large amount of the variation observed in petal number in this species. We also know that an important gene controlling petal development called LEAFY maps to this genomic region. In order to identify genes that repress petal number in hairy bittercress we induced variation in the genome by mutagenesis and identified mutants that convert hairy bittercress to thale cress petal number. Identifying the genes mutated in these plants will tell us which genes act to reduce petal number in hairy bittercress but not in thale cress. One way that LEAFY regulates petal development is by turning on expression of the APETALA1 gene. Other regulators in thale cress but not in hairy bittercress also turn on this gene. We want to know whether this difference in gene regulation plays a part in making these two species look different from each other. Here, we will determine whether LEAFY or a different gene controls the variation observed in hairy bittercress populations. We will also identify genes that act only in hairy bittercress to reduce petal number. Many of the genetic changes during evolution that produce different-looking species result from changes in the way genes are regulated and we will test whether this is true for the APETALA1 gene in these two mustard species. Thus, species-specific differences in petal number between hairy bittercress and thale cress, and natural variation in this trait between hairy bittercress populations around the world, provide an exciting experimental platform to trace evolution from specific changes in gene regulation through to altered morphologies in nature. Another group of mustards called Brassicas are remarkable for containing more important agricultural and horticultural crops than any other plant genus. Understanding the genetic basis of mustard diversity is therefore a vital part of generating crops for the 21st century.