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A programme for studying the role of microtubule-associated proteins in xylem formation

研究微管相关蛋白在木质部形成中的作用的程序

基本信息

批准号：
BB/G008019/1
负责人：
Clive Lloyd
金额：
$ 58.97万
依托单位：
John Innes Centre
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2009
资助国家：
英国
起止时间：
2009 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FG008019%2F1
关键词：
programme studying role microtubule associated

项目摘要

As shoots grow into the atmosphere, water and minerals are transported from the roots to the advancing leaves. This occurs in specialized transport tissue called xylem. Xylem contains cells called tracheary elements (because early microscopists thought they look like animal breathing tubes / trachea). Tracheary elements form conducting pipes by thickening their walls with spirals or hoops of new wall material; they then hollow their contents by programmed cell death and the end-walls become perforated allowing continuous flow from cell to cell. Actively conducting xylem is found in sapwood but, later, the cells become more thickened to form inactive heartwood - the supporting material of wood. We need to know how wood-forming cells form in order to rationally manipulate this material. Previously, by grinding leaves of the plant, Zinnia, it was possible to convert some cells to xylem cells in the test tube. We have worked on Zinnia but its genetic information is not sequenced, making it very difficult to do molecular biology. Others have shown that cells of Arabidopsis (whose genome has been sequenced) can also be induced to become xylem cells in the test tube but this occurs with low efficiency and in clumps. Now, we have found a way of converting single Arabidopsis suspension cells into xylem cells synchronously, with high efficiency, time after time. This gives us an important lead and in preliminary work we have shown that all parts of the following programme are feasible. Just before cell death, the cytoplasm in xylem cells undergoes a striking reorganization, forming circumferential bands that exactly match the thickening ribs of cell wall. This is due to the bunching-up of microtubules (the cell's 'scaffolding rods') attached to the inside of the cell membrane. Microtubules act as tracks for enzymes that move along the membrane, extruding cellulose microfibrils into the cell wall. This explains the coincidence between the patterns formed by microtubules and the thickened ribs of cell wall. Synchronous formation of tracheary elements is therefore an ideal model system for following how microtubules bunch together, particularly since the highly visible wall thickenings can be easily monitored in systematic screens. We want to screen the microtubule-associated proteins that influence the organization of microtubules during xylem cell formation. We propose studying the entire collection of genes in Arabidopsis to see which ones are switched on/off as xylem cells form ('transcriptomics'). We will then compare these with the actual proteins that bind microtubules in the test tube ('proteomics'). By examining all known microtubule-associated proteins, and possibly identifying novel ones, we will select those that are active during cell formation. Then we will interfere with these genes to test our hypothesis that changes in the behaviour and organization of microtubules will change the pattern of thickening in the cell wall. We will user laser microscopy to follow the changes in microtubule behaviour that result in the different wall sculpturings.

当嫩芽长到大气中时，水和矿物质从根部输送到生长的叶子上。这发生在专门的运输组织称为木质部。木质部含有称为气管元件的细胞（因为早期的显微镜学家认为它们看起来像动物的呼吸管/气管）。导管分子通过用新的壁材料的螺旋或箍增厚其壁而形成导管;然后通过程序性细胞死亡使其内容物中空，并且端壁变得穿孔，从而允许从细胞到细胞的连续流动。活跃的木质部存在于边材中，但随后，细胞变得更加增厚，形成不活跃的心材-木材的支撑材料。我们需要知道木材形成细胞是如何形成的，以便合理地操纵这种材料。以前，通过研磨植物百日菊的叶子，可以在试管中将一些细胞转化为木质部细胞。我们已经研究过百日菊，但它的遗传信息没有测序，这使得分子生物学研究非常困难。其他人已经表明，拟南芥的细胞（其基因组已被测序）也可以在试管中被诱导成为木质部细胞，但这种情况发生的效率很低，而且是成团的。现在，我们已经找到了一种将单个拟南芥悬浮细胞一次又一次地同步高效转化为木质部细胞的方法。这给了我们一个重要的线索，在初步工作中，我们已经表明，以下方案的所有部分都是可行的。在细胞死亡之前，木质部细胞的细胞质发生了显著的重组，形成了与细胞壁加厚棱完全吻合的环带。这是由于微管（细胞的“支架杆”）聚集在细胞膜内部。微管充当酶的轨道，酶沿着膜移动，将纤维素微纤维挤压到细胞壁中。这解释了微管形成的图案与细胞壁加厚的肋之间的一致性。因此，气管元件的同步形成是一个理想的模型系统，用于跟踪微管如何聚束在一起，特别是因为高度可见的壁增厚可以很容易地在系统屏幕中监测。我们希望筛选在木质部细胞形成过程中影响微管组织的微管相关蛋白。我们建议研究拟南芥中的整个基因集合，看看哪些基因在木质部细胞形成时被打开/关闭（“转录组学”）。然后我们将这些与试管中结合微管的实际蛋白质进行比较（“蛋白质组学”）。通过检查所有已知的微管相关蛋白，并可能识别新的，我们将选择那些在细胞形成过程中活跃。然后，我们将干扰这些基因来验证我们的假设，即微管行为和组织的变化将改变细胞壁增厚的模式。我们将使用激光显微镜来跟踪微管行为的变化，这些变化导致了不同的壁雕刻。