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A new model for chloroplast-to-nucleus communication during seedling development

幼苗发育过程中叶绿体与细胞核通讯的新模型

基本信息

批准号：
BB/J018139/1
负责人：
Matthew Terry
金额：
$ 49.75万
依托单位：
University of Southampton
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2013
资助国家：
英国
起止时间：
2013 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FJ018139%2F1
关键词：
new model chloroplast nucleus communication

项目摘要

The ability of plants to use sunlight for photosynthesis is an essential process that supports life on Earth. Photosynthesis represents the most significant source of new energy to the planet and is therefore central to our considerations on future energy needs. Much of our food is also derived from plants, either directly from vegetables, cereals etc, or indirectly as a source of animal food. In plants (and algae), photosynthesis takes place in organelles called chloroplasts. Most of the 2000-3000 proteins contained in the chloroplast are synthesized from DNA present in another organelle called the nucleus, although the chloroplast can make about 80 of its own proteins. When a new chloroplast is made (chloroplast biogenesis), the important role played by the nucleus means that the two organelles need to communicate. We know quite a lot about how the nucleus sends information to chloroplasts, but the mechanisms by which chloroplasts communicate with the nucleus have remained poorly understood despite over 30 years of research in this area. In this proposal we have taken a large body of published information and used it to develop a model for chloroplast-to-nucleus communication. The principal aim of this proposal is to robustly test this model to see if it is correct.The model proposes two pathways: a promotive pathway in which chloroplasts signal to the nucleus that all is well; and a second, inhibitory pathway that is activated when things go wrong. Specifically, the accumulation of intermediates in the synthesis of the green, photosynthetic pigment, chlorophyll, activates the inhibitory pathway when these pigments are excited by light. The inhibitory pathway then reduces the amount of chlorophyll being made. Such an inhibitory pathway would be important as most chloroplasts are made during early seedling development and too many chlorophyll intermediates would be lethal to a seedling because in the light they are photo-toxic.The promotive pathway is proposed to be mediated by heme, a molecule related to chlorophyll. We will test whether heme is involved by making plants that contain excess of the heme biosynthesis enzyme ferrochelatase or the heme-degrading enzyme heme oxygenase. We will ascertain whether these plants are still able to communicate between chloroplasts and the nucleus by using assays that measure the expression of specific nuclear genes under a range of different conditions. The second way we will test the model is to examine the role of an important protein in chloroplast-to-nucleus communication called GUN1. This is a chloroplast protein that has been proposed by others to be important in the signaling pathway between chloroplasts and the nucleus. In our model we propose that this is incorrect, and that instead the GUN1 protein has a role in chloroplast biogenesis itself that affects the making of the chloroplast signal. We will test whether this is the case by looking carefully at processes involved in chloroplast biogenesis in mutants lacking GUN1 and conversely in plants that contain excess GUN1 protein. We will determine whether these plants lack the ability to make the chloroplast promotive signal required to maintain nuclear gene expression.Finally, we will investigate the inhibitory pathway. In a previous study we isolated mutants that were unable to use the inhibitory pathway to reduce nuclear gene expression. In this proposal we will determine which genes are affected in these mutants and use this information to better understand how this pathway might work.Signals from chloroplasts to the nucleus have been implicated in all sorts of responses to changing environments such as to cold and drought. Our results may have important implications for understanding how plants interact with their changing environment, information that may be important in the future for producing better food and energy crops.

植物利用阳光进行光合作用的能力是维持地球生命的一个重要过程。光合作用是地球最重要的新能源来源，因此是我们考虑未来能源需求的核心。我们的大部分食物也来自植物，要么直接来自蔬菜、谷物等，要么间接作为动物食品的来源。在植物（和藻类）中，光合作用发生在称为叶绿体的细胞器中。叶绿体中包含的 2000-3000 种蛋白质中的大多数是由另一个称为细胞核的细胞器中的 DNA 合成的，尽管叶绿体本身可以制造大约 80 种蛋白质。当形成新的叶绿体（叶绿体生物发生）时，细胞核发挥的重要作用意味着两个细胞器需要进行通信。我们对细胞核如何向叶绿体发送信息了解颇多，但尽管该领域的研究已超过 30 年，但对叶绿体与细胞核通讯的机制仍知之甚少。在这个提案中，我们采用了大量已发表的信息，并用它来开发叶绿体到细胞核通信的模型。该提议的主要目的是稳健地测试该模型，看看它是否正确。该模型提出了两种途径：一种是叶绿体向细胞核发出一切正常的信号的促进途径；另一种是叶绿体向细胞核发出一切正常的信号的促进途径。第二条是当出现问题时激活的抑制途径。具体来说，当这些色素被光激发时，绿色光合色素叶绿素合成过程中中间体的积累会激活抑制途径。然后抑制途径减少了叶绿素的产生量。这种抑制途径非常重要，因为大多数叶绿体是在幼苗发育早期形成的，过多的叶绿素中间体对幼苗来说是致命的，因为它们具有光毒性。促进途径被认为是由血红素（一种与叶绿素相关的分子）介导的。我们将通过制作含有过量血红素生物合成酶亚铁螯合酶或血红素降解酶血红素加氧酶的植物来测试血红素是否参与其中。我们将通过在一系列不同条件下测量特定核基因表达的测定来确定这些植物是否仍然能够在叶绿体和细胞核之间进行通讯。我们测试模型的第二种方法是检查一种重要蛋白质（称为 GUN1）在叶绿体与细胞核通讯中的作用。这是一种叶绿体蛋白，其他人认为它在叶绿体和细胞核之间的信号传导途径中很重要。在我们的模型中，我们认为这是不正确的，相反，GUN1 蛋白在叶绿体生物发生本身中发挥作用，影响叶绿体信号的产生。我们将通过仔细观察缺乏 GUN1 的突变体和含有过量 GUN1 蛋白的植物中涉及叶绿体生物发生的过程来测试情况是否如此。我们将确定这些植物是否缺乏产生维持核基因表达所需的叶绿体促进信号的能力。最后，我们将研究抑制途径。在之前的一项研究中，我们分离出了无法利用抑制途径降低核基因表达的突变体。在本提案中，我们将确定哪些基因在这些突变体中受到影响，并利用这些信息更好地了解该途径如何发挥作用。从叶绿体到细胞核的信号与对变化的环境（例如寒冷和干旱）的各种反应有关。我们的结果可能对了解植物如何与其不断变化的环境相互作用产生重要影响，这些信息对于未来生产更好的粮食和能源作物可能很重要。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

The iron-sulfur cluster biosynthesis protein SUFB is required for chlorophyll synthesis, but not phytochrome signaling.

DOI：
10.1111/tpj.13455
发表时间：
2017-03
期刊：
The Plant journal : for cell and molecular biology
影响因子：
0
作者：
Hu X;Page MT;Sumida A;Tanaka A;Terry MJ;Tanaka R
通讯作者：
Tanaka R

A chloroplast-localized protein LESION AND LAMINA BENDING affects defence and growth responses in rice.

DOI：
10.1111/nph.13864
发表时间：
2016-02
期刊：
The New phytologist
影响因子：
0
作者：
Muluneh Tamiru;H. Takagi;A. Abe;T. Yokota;H. Kanzaki;H. Okamoto;H. Saitoh;Hideyuki Takahashi;K. Fujisaki;Kaori Oikawa;Aiko Uemura;S. Natsume;Y. Jikumaru;H. Matsuura;K. Umemura;M. J. Terry;R. Terauchi
通讯作者：
Muluneh Tamiru;H. Takagi;A. Abe;T. Yokota;H. Kanzaki;H. Okamoto;H. Saitoh;Hideyuki Takahashi;K. Fujisaki;Kaori Oikawa;Aiko Uemura;S. Natsume;Y. Jikumaru;H. Matsuura;K. Umemura;M. J. Terry;R. Terauchi

Overexpression of chloroplast-targeted ferrochelatase 1 results in a genomes uncoupled chloroplast-to-nucleus retrograde signalling phenotype.

叶绿体靶向亚铁螯合酶 1 的过度表达会导致基因组解偶联叶绿体与细胞核的逆行信号传导表型。