A novel genome-wide approach to understand the genetic basis for morphological diversification of leaves

生物学中的一个关键问题是理解不同的有机体是如何形成不同的形式的。在植物中，这种形式的变化在公园散步时看到的许多不同的叶子形状中都很明显。叶片也是值得研究的，因为它们在食物链中扮演着关键角色，是陆地植物的主要光合器官，因此在陆地生态系统中负责固定二氧化碳。出于这些原因，了解树叶形态的多样性是如何产生的，这对科学家来说是相当感兴趣的。为了研究这个问题，我们用毛茸茸的苦菜(Cardamine Hirsuta)来研究这个问题，这种植物的叶子完全细分为更小的小叶。小叶的存在使这种植物与它的近亲拟南芥(Arabiopsis Thaliana)非常不同，后者有完整的、不分裂的叶子。我们已经知道了很多关于水芹是如何产生整个叶子形状的，因为它很容易种植和做实验。毛茸茸的苦菜在实验室里也很容易处理，所以我们用它来了解传单是如何产生的。现在，我们想要了解毛茸茸的苦菜和水芹的基因构成是如何不同的，从而导致只在前者的物种中产生小叶。具体地说，我们将测试多毛苦菜叶是否会产生小叶，因为这种植物中的某些基因携带着与水芹基因不同的信息。为了实现这一点，我们将把毛茸茸的苦菜基因组分成许多小片段，并将每个基因组片段引入到水芹中。为数不多的接收到产生部分毛茸茸的苦菜基因组的小叶的水芹植物现在应该长出类似于毛茸茸的苦菜分裂的叶子。这种方法将使我们能够分离“小叶产生”基因，并找出“小叶产生信息”是否存在于控制基因表达时间、地点和数量的调控序列中，还是存在于决定基因产物生化活性的蛋白质编码序列中。分离出这些产生小叶的基因将成为未来研究的基础，我们将在苦菜中减少或增加它们的活动，以测试小叶产生对它们活动变化的敏感程度。

A key problem in biology is to understand how different organisms come to have different forms. In plants, this variation in form is obvious in the many different leaf shapes one sees during a walk in the park. Leaves are also interesting to study because they play a key role in the food chain being the main photosynthetic organs of land plants and thus responsible for CO2 fixation in terrestrial ecosystems. For these reasons, understanding how diversity in leaf form is generated is of considerable interest to scientists. To study this problem we work with hairy bittercress (Cardamine hirsuta), which is a plant that has leaves fully subdivided into smaller leaflets. The presence of leaflets makes this plant very different to its close relative thale cress (Arabidopsis thaliana), which has entire, undivided leaves. We already know a lot about how an entire leaf shape is produced in thale cress because it is easy to grow and do experiments with. Hairy bittercress is also very easy to work with in the lab, so we use it to understand how leaflets are produced. We now want to understand how the genetic make up of the hairy bittercress differs to that of the thale cress resulting in leaflets being produced in only the former species . Specifically we will test whether hairy bittercress leaves produce leaflets because certain genes in this plant carry different information to thale cress genes. To achieve this we will divide the hairy bittercress genome into many small pieces and introduce each piece of this genome into the thale cress. The few thale cress plants that receive a 'leaflet producing' part of the hairy bittercress genome should now produce leaves that resemble the divided leaves of hairy bittercress. This approach will allow us to isolate 'leaflet producing' genes and find out whether the 'leaflet producing information' resides in the regulatory sequences that control when, where and how much a gene is expressed, or in the protein-coding sequences that determine the biochemical activity of a gene product. Isolation of such 'leaflet producing genes' will form the basis for future research where we will reduce or increase their activity within bitter cress to test to what degree leaflet production is sensitive to alterations of their activity.