Genetic engineering of higher leaf vein density in rice towards improved yield

通过基因工程提高水稻叶脉密度以提高产量

• 批准号: RGPIN-2014-05998
• 负责人: Mattsson, Jim
• 金额: $ 2.48万
• 依托单位: Simon Fraser University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=659064
• 关键词: Genetic; engineering; higher; leaf; vein

The world's population will reach an estimated 9.1 billion by the year 2050. How will we feed this population when currently 1 billion people already are chronically hungry? Rice and wheat provide more food than any other crops. Big production increases in these crops will be hard to achieve for several reasons. Both species, utilizing the most common variant of photosynthesis known as C3, have reduced photosynthetic yield due to a process known as photorespiration especially in environments with high temperatures and reduced access to water. Global warming is already exacerbating these problems.**There is a world-wide effort underway to explore the possibility of reducing photorespiration in rice and wheat by engineering traits typical of plants utilizing C4 photosynthesis. A conversion to C4 traits could increase yields to levels approaching that of maize, a C4 plant, whose photosynthetic yield at higher temperatures is 50% higher than rice. C4 plants concentrate CO2 in bundle sheath cells surrounding leaf veins, thereby avoiding photorespiration. Since C4 photosynthesis is associated with leaf veins, C4 plants require a high vein density for a high yield of photosynthates. While considerable advances have been made in the understanding of the molecular genetic basis of C4 photosynthesis, the fundamental requirement of a high vein density is unresolved. **We have pioneered work demonstrating that higher vein density can be obtained in dicot plants by manipulating transport and distribution of the plant hormone auxin. We have now obtained similar evidence for monocots, including wheat and rice. We have also demonstrated that access to undetermined ground cells strongly influences the response to auxin and the formation of higher vein density. Taken together, this puts my laboratory in an excellent position to generate rice plants with genetically induced higher leaf vein density. We propose to approach this problem from four parallel directions; to increase levels of inductive auxin, to increase to the perception of auxin, to reduce canalization of auxin and finally, to provide a larger number of immature ground cells that can respond to auxin by vein formation. We also seek to identify genes involved in the differentiation of the enhanced bundle-sheath layer typical of C4 leaf veins.**This program will allow us to generate a basic understanding of the parameters that regulate vein patterning in monocot plants. More important, present data together with the parallel approaches that we are taking provide high chance of success in enhancing leaf vein density on rice. This will allow us to collaborate with and potentially get funded by international efforts to engineer C4 rice and ultimately also C4 wheat to increase food production. **There are several potential long-term benefits of this program to Canada. First, it may become a substantial contribution to addressing future food security in the world, which is of interest to Canada from humanitarian, economical and political perspectives. Second, the outcomes of this program can also be applied to Canadian crops, primarily wheat and canola, grown in large scale in Canada. These crops experience high temperatures as well as periodic drought, leading to reduced yield in large part due to photorespiration.

到2050年，世界人口估计将达到约91亿。当目前10亿人已经长期饥饿时，我们将如何养活这一人口？大米和小麦提供的食物比其他任何农作物都多。 由于几个原因，这些农作物的生产大量增加将很难获得。 利用最常见的光合作用变体称为C3，这两种物种都降低了光合作用的产量，这是由于一种称为光捕集的过程，尤其是在高温和降低水的环境中。全球变暖已经加剧了这些问题。转换为C4特征可以将接近C4植物的水平提高到接近水平的水平，C4植物的光合产量比大米高出50％。 C4植物将二氧化碳浓缩在叶静脉周围的束鞘细胞中，从而避免了光刺。由于C4光合作用与叶静脉有关，因此C4植物需要高静脉密度才能获得高产物的光合作用。尽管在理解C4光合作用的分子遗传基础方面已经取得了很大的进步，但尚未解决高静脉密度的基本要求。 **我们的开创性工作表明，通过操纵植物激素生长素的运输和分布可以在DICOT植物中获得较高的静脉密度。现在，我们已经获得了包括小麦和大米在内的单子叶植物的类似证据。我们还证明，访问未确定的地面细胞会强烈影响对生长素的反应和较高静脉密度的形成。综上所述，这使我的实验室处于极好的位置，以产生具有遗传诱导较高叶静脉密度的水稻植物。我们建议从四个平行方向解决这个问题。为了增加诱导生长素的水平，以增加生长素的感知，以减少生长素的管道化，最后提供大量的未成熟地面细胞，这些细胞可以通过静脉形成对生长素反应。我们还试图确定与C4叶静脉典型的增强束鞘层鉴定有关的基因。更重要的是，目前的数据以及我们正在采用的平行方法为增强大米上的叶静脉密度提供了很大的成功机会。这将使我们能够与国际米饭的努力合作，并有可能由C4米饭的国际努力资助，并最终还可以通过C4小麦来增加食品生产。 **该计划对加拿大有一些潜在的长期利益。首先，它可能成为解决世界未来粮食安全的实质性贡献，从人道主义，经济和政治角度来看，加拿大对加拿大感兴趣。 其次，该计划的结果也可以应用于加拿大大规模生长的加拿大作物，主要是小麦和低芥酸菜籽。这些农作物经历了高温和周期性干旱，从而导致产量降低，这在很大程度上是由于光呼吸的。