Mechanisms of C4 Photosynthetic Evolution

C4光合进化机制

基本信息

批准号：
RGPIN-2017-06476
负责人：
Sage, Rowan
金额：
$ 4.23万
依托单位：
University of Toronto
依托单位国家：
加拿大
项目类别：
Discovery Grants Program - Individual
财政年份：
2020
资助国家：
加拿大
起止时间：
2020-01-01 至 2021-12-31
项目状态：
已结题

来源：
https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=712245
关键词：
Mechanisms C4 Photosynthetic Evolution

项目摘要

C4 photosynthesis enhances productivity and resource-use efficiency in higher plants by inhibiting the wasteful process of photorespiration. Despite its advantages, few major food and fiber crops use the C4 pathway, relying instead on the C3 pathway which can suffer from high rates of photorespiration. To meet growing demands for food, fiber and fuel, there is much interest in further exploiting C4 photosynthesis, either through the engineering of the C4 pathway into C3 crops, improving existing C4 crops, or domesticating wild C4 species. The Sage lab at the University of Toronto is a recognized leader in C4 plant biology, with expertise at the interfaces between molecular mechanisms, genomics, whole plant physiology, photosynthetic evolution, systematics, and ecology/biodiversity. Through our efforts, we have shown that C4 photosynthesis evolved at least 65 times, indicating it is relatively easy to evolve in nature and for humanity to engineer into our C3 crops, such as wheat and rice. By studying how C4 plants evolved, we should be able to learn how to engineer the C4 pathway into C3 plants, and to improve existing C4 crops. In this proposal, funds are requested to support research that will elucidate the physiological, developmental, and molecular mechanisms governing the evolution of C4 photosynthesis. To support this work, we have acquired the world's largest collection of related C3, C4 and C3-C4 intermediate species from 34 independent origins of C4 photosynthesis, including a diverse set of C3-C4 intermediate species from nine C4 evolutionary lineages. This diversity will enable us to use a comparative approach to examine the physiological, developmental and molecular mechanisms by which C4 photosynthesis evolved. In the comparative studies, we will characterize C4 trait acquisition along an evolutionary gradient in genera such as Blepharis and Flaveria, which contain multiple species with intermediate C3- C4 traits. Trait acquisition will then be compared with the species' transcriptomes to identify corresponding shifts in gene expression. We have also generated fertile hybrids of C3 and C4 species of Atriplex which exhibit segregation of C4 traits. Using a combined analysis of parental gene assortment in the transcriptomes of the hybrids, along with measurement of leaf physiology, cell biology and development, we will be able to link genetic controls with the expression of specific C4 traits. Together, the comparative approach and the hybrid analysis will provide us with an unprecedented ability to discover critical controls over C4 trait expression, and to address when during the evolutionary process they were engaged. Through our work, novel gene candidates will be funneled to the C4 Rice effort, contributing to the success of a program that could improve the efficiency of major crops such as rice and wheat by 50% or more, thus eliminating world hunger for the foreseeable future.

C4 光合作用通过抑制光呼吸的浪费过程来提高高等植物的生产力和资源利用效率。尽管有其优点，但很少有主要粮食和纤维作物使用 C4 途径，而是依赖 C3 途径，而 C3 途径可能会遭受高光呼吸率的影响。为了满足对食物、纤维和燃料不断增长的需求，人们对进一步利用 C4 光合作用非常感兴趣，无论是通过将 C4 途径工程化到 C3 作物中，改良现有的 C4 作物，还是驯化野生 C4 物种。多伦多大学的 Sage 实验室是 C4 植物生物学领域公认的领导者，在分子机制、基因组学、全植物生理学、光合进化、系统学和生态学/生物多样性之间的交叉领域拥有专业知识。通过我们的努力，我们已经证明 C4 光合作用至少进化了 65 次，这表明它在自然界中进化相对容易，并且对于人类来说，将其改造到我们的 C3 作物（例如小麦和水稻）中是相对容易的。通过研究 C4 植物如何进化，我们应该能够了解如何将 C4 途径改造为 C3 植物，并改进现有的 C4 作物。在该提案中，需要资金支持阐明控制 C4 光合作用进化的生理、发育和分子机制的研究。为了支持这项工作，我们从 34 个独立的 C4 光合作用起源获得了世界上最大的相关 C3、C4 和 C3-C4 中间物种集合，其中包括来自 9 个 C4 进化谱系的多样化 C3-C4 中间物种。这种多样性将使我们能够使用比较方法来研究 C4 光合作用进化的生理、发育和分子机制。在比较研究中，我们将沿着 Blepharis 和 Flaveria 等属的进化梯度描述 C4 性状的获得，这些属包含多个具有中间 C3-C4 性状的物种。然后将获得的性状与物种的转录组进行比较，以确定基因表达的相应变化。我们还培育了滨藜 C3 和 C4 物种的可育杂种，其表现出 C4 性状的分离。通过对杂种转录组中亲本基因分类的综合分析，以及叶生理学、细胞生物学和发育的测量，我们将能够将遗传控制与特定 C4 性状的表达联系起来。比较方法和混合分析将为我们提供前所未有的能力，以发现对 C4 性状表达的关键控制，并解决它们在进化过程中何时参与。通过我们的工作，新的候选基因将被输送到 C4 水稻项目中，为一项计划的成功做出贡献，该计划可以将水稻和小麦等主要作物的效率提高 50% 或更多，从而在可预见的未来消除世界饥饿。