Collaborative Research: Exploiting Prokaryotic Proteins to Improve Plant Photosynthetic Efficiency

光呼吸可以造成C3植物25-50%的产量损失，其中包括水稻、小麦和大豆，这是全球粮食产量排名前四的作物中的三种。光呼吸的发生是因为氧气和二氧化碳在光合作用中争夺同一受体分子。这个过程可以很简单地通过增加二氧化碳浓度来抑制。当在温室或露天地里人为增加二氧化碳时，可获得非常显著的产量增加。然而，在数百万英亩的土地上人为地增加二氧化碳是不可行的。一些蓝藻通过将碳固定在一种称为羧基体的结构中来解决这个问题，在这种结构中，特定酶的定位会引起二氧化碳的浓度。虽然含有作物光合作用机制的叶绿体缺乏羧酸体，但它们是从蓝藻细菌进化而来的，蓝藻细菌被共生地吸收到今天的植物和作物的祖先中。该研究项目将为合成生物学方法提供基础，其中羧基体将被设计到作物的叶绿体中以增强光合作用。优化将包括操作一个易于转换的模型植物和系统的计算机模型的开发，以评估不同蛋白质的使用和所需的最小系统。一个多学科的方法将通过四个研究小组的合作来实施，每个研究小组都提供互补的专业知识：羧基体遗传学和组装（伯克利），叶绿体和核转化（康奈尔），光合系统建模（伊利诺伊）和整个植物的生理和生化特征（洛桑，康奈尔和伊利诺伊）。该项目将允许博士后和本科生学员在国际合作项目中获得经验（全部）。将开发比较植物和细菌基因的研究资源，用于本科教育（伯克利）。

Photorespiration can account for yield losses of 25-50% in C3 plants, which include rice, wheat and soybean, three of the top four crops in terms of global grain production. Photorespiration occurs because oxygen and carbon dioxide (CO2) compete for the same acceptor molecule in photosynthesis. The process can be very simply inhibited by increasing the concentration of CO2. When CO2 is increased artificially in greenhouses or in open fields, very significant yield increases are obtained. However, artificially elevating CO2 over millions of acres of fields is not feasible. Some cyanobacteria solve this problem by confining the fixation of carbon to a structure termed a carboxysome, where localization of specific enzymes cause a concentration of CO2. Although chloroplasts, which contain the photosynthetic machinery of crops, lack carboxysomes, they evolved from cyanobacteria, which were symbiotically recruited into the ancestors of todays plants and crops. This research project will provide the foundation for a synthetic biology approach in which carboxysomes will be engineered into the chloroplasts of crop plants to enhance photosynthesis. Optimization will involve manipulating a model plant that is readily transformable and the development of an in silico model of the system to evaluate the use of different proteins and the minimal system that is needed. A multidisciplinary approach will be implemented through collaboration of four research groups, each contributing complementary expertise: carboxysome genetics and assembly (Berkeley), chloroplast and nuclear transformation (Cornell), photosynthetic systems modelling (Illinois) and physiological and biochemical characterization of the whole plant (Rothamsted, Cornell and Illinois). The project will allow postdoctoral and undergraduate trainees to gain experience in an international collaborative project (All). Research resources for comparing plant and bacterial genes will be developed for use in undergraduate education (Berkeley).