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Genetic manipulation of photoprotection and photooxidative stress tolerance in rice

水稻光保护和光氧化胁迫耐受性的遗传操作

基本信息

批准号：
BB/G003157/1
负责人：
Erik Murchie
金额：
$ 50.24万
依托单位：
University of Nottingham
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%2FG003157%2F1
关键词：
Genetic manipulation photoprotection photooxidative stress

项目摘要

All plants, including crop plants need to absorb light energy from the sun in order to grow, develop and eventually produce a harvestable product such as fruit or grain. Light is needed for plant development and it is also needed in photosynthesis where it is combined with carbon dioxide and water to synthesis sugars. The amount of light available cannot be controlled by the plants and depending on climatic factors, photosynthesis can be limited by light or it can absorb more than it needs. When too much light is absorbed, or 'harvested' there is a real danger that the energy will be passed to oxygen to form radicals which will damage plant tissues and even cause plant death. There are a number of mechanisms operating at the molecular level which sense the amount of surplus energy and 'dissipate' it harmlessly in a process called non photochemical quenching or NPQ. One mechanism involves the protein called PsbS which is present in all plants and acts as a 'switch' between light harvesting and energy dissipation. Another mechanism involves the synthesis of carotenoid molecules (specifically xanthophyll cycle XC carotenoids) which are colourful pigments (also present in all plants). They are also important antioxidants in the human diet. In plants they have a dual role: firstly they too regulate the process of NPQ, 'tuning' it to last a short or a long time. Secondly they are proven and powerful antioxidants in leaves, preventing damage to membranes. So far these molecules have only been investigated in the model plant Arabidopsis thaliana. There is a real need to investigate how these properties could be used in crop plants in order to improve growth and yield especially in stressful situations such as heat, drought or cold where, combined with high light, much damage from oxygen radicals can occur. This project uses a model crop, rice, in which the levels of PsbS and XC carotenoids have been manipulated by plant transformation procedures. Rice was chosen because it is easy to transform and has a sequenced genome. Plants with raised and lowered amounts of PsbS and raised and lowered amounts of XC carotenoids have been produced. The objectives of this proposal are to test the effects of these alterations on the efficiency with which light is absorbed and utilised by the plant. Are they at optimum levels or can we improve them? Secondly these plants, especially with raised levels of XC carotenoids should have an enhanced resistance to stress where membranes are the target, for example cold or heat and in the light. We will look for an enhanced tolerance to these stresses.. We will examine the biochemistry of plant membranes to find out how much more, or less, resistance exists. Lastly we will examine the growth rate and the potential for production of these plants in situations similar to growth in the field for grain production. We will find out whether the enhanced level of resistance to stress and the altered light use efficiency has a cost for the plant, or if it provides a real advantage. An important question to ask is whether the natural fluctuating levels of light we see outside in the field situations is efficiently converted by these processes or whether there is scope for improvement. There is good reason to believe that this project will show that we can make crop plants more resistant to environmental stress. Responses of plants to environmental stress should become more important as the impact of climate change is felt by agriculture. Additionally these processes should be of benefit to all crop plants including those which are used for energy crops or biofuels.

所有植物，包括农作物，都需要从太阳吸收光能，以生长、发育并最终产生可收获的产品，如水果或谷物。光是植物发育所必需的，它也是光合作用所必需的，在光合作用中，它与二氧化碳和水结合以合成糖。可用的光量不能由植物控制，并且取决于气候因素，光合作用可以受到光的限制，或者它可以吸收超过其需要的光。当过多的光被吸收，或“收获”有一个真实的危险，能量将被传递到氧气形成自由基，这将损害植物组织，甚至导致植物死亡。有许多机制在分子水平上运作，这些机制可以感知剩余能量的数量，并在称为非光化学猝灭或NPQ的过程中无害地“消散”它。其中一种机制涉及一种名为PsbS的蛋白质，它存在于所有植物中，充当光捕获和能量耗散之间的“开关”。另一种机制涉及类胡萝卜素分子（特别是叶黄素循环XC类胡萝卜素）的合成，它们是彩色色素（也存在于所有植物中）。它们也是人类饮食中重要的抗氧化剂。在植物中，它们有双重作用：首先，它们也调节NPQ的过程，“调整”它以持续较短或较长的时间。其次，它们是叶子中经过验证的强大抗氧化剂，防止对膜的损害。到目前为止，这些分子仅在模式植物拟南芥中进行了研究。真实的需要研究如何将这些性质用于作物植物中，以改善生长和产量，特别是在诸如热、干旱或寒冷的应激情况下，在这些情况下，结合强光，可能发生来自氧自由基的许多损害。该项目使用了一种模式作物，水稻，其中PsbS和XC类胡萝卜素的水平已被植物转化程序操纵。之所以选择水稻，是因为它很容易转化，而且有一个测序的基因组。已经产生了PsbS含量升高和降低以及XC类胡萝卜素含量升高和降低的植物。本提案的目的是测试这些改变对植物吸收和利用光的效率的影响。它们是否处于最佳水平，或者我们可以改进它们？其次，这些植物，特别是XC类胡萝卜素水平升高的植物，应该对膜为目标的胁迫具有增强的抗性，例如冷或热以及光照。我们将寻求增强对这些压力的耐受性。我们将研究植物细胞膜的生物化学，以找出抗性存在的程度。最后，我们将研究这些植物的生长速度和生产潜力，这些植物的生长情况与谷物生产领域的生长情况相似。我们将发现增强的抗胁迫水平和改变的光利用效率是否对植物有成本，或者它是否提供了真实的优势。一个重要的问题是，我们在野外环境中看到的自然波动的光线水平是否可以通过这些过程有效地转换，或者是否有改进的余地。有充分的理由相信，这个项目将表明，我们可以使作物植物更能抵抗环境压力。随着气候变化对农业的影响，植物对环境压力的反应应该变得更加重要。此外，这些过程应该有利于所有作物，包括用于能源作物或生物燃料的作物。