Engineering an inorganic carbon highway to improve C3 photosynthesis

光合作用除了在减少大气二氧化碳方面发挥重要作用外，还显示出提高作物产量的巨大潜力，这仍然是基因工程的目标。光合作用通过固碳提供了世界上大部分的生物量。通过学习如何在模式植物中为碳固定酶Rubisco提供更多的碳酸氢盐，正在开发可应用于作物植物的技术。该项目使用合成生物学方法来增加对Rubisco的碳酸氢盐供应，从而增强模式植物的光合作用。学员从事涉及遗传学、生物化学和分子生物学的多学科项目。来自不同群体的本科生在学年和夏季期间获得研究经验。通过网站和Youtube频道上的指导性视频，对公众进行了新的教育。计划与公共广播服务电台合作制作专业视频，解释利用合成生物学增强光合作用以及植物在从大气中去除二氧化碳方面的作用。该视频将通过PBS学习媒体提供给K-12教育。大约85%的C3作物，包括大豆和小麦等粮食作物，缺乏将二氧化碳集中在Rubisco附近的能力。基于蓝藻和藻类中存在的碳浓缩机制，在作物植物中合成碳浓缩机制（CCM）有可能大幅提高产量。安装基于微室的CCM不仅需要在叶绿体内实际构建微室，还需要提供额外的碳酸氢盐，碳酸氢盐可以转化为二氧化碳。为了评估来自微生物的碳酸氢盐转运体是否可以在叶绿体中发挥作用，将其编码基因转化为叶绿体碳酸酐酶被去除的突变背景。突变体中碳酸酐酶的缺失导致受损的、缺乏碳酸氢盐的表型，预计这种表型会被一个功能性的碳酸氢盐转运体所拯救。对转化后的植物进行分析，不仅是为了挽救需要碳酸氢盐的表型，而且是为了研究对光合作用、生长、活性氧、基质pH和脂肪酸合成的影响。除了在C3植物的碳浓缩机制的改造工程中提供必要的步骤外，建模预测，即使在安装完整的微室型CCM之前，仅将无机碳泵结合到叶绿体中也可以提高产量。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Photosynthesis remains a target for genetic engineering that exhibits great potential for enhancing crop yield, in addition to its important role in reducing atmospheric carbon dioxide. Photosynthesis provides most of the world’s biomass through carbon fixation. By learning how to provide increased bicarbonate to the carbon-fixing enzyme Rubisco in a model plant, technology is being developed that can be applied to crop plants. This project uses synthetic biology approaches to increase bicarbonate supply to Rubisco, and consequently enhance photosynthesis, in a model plant. Trainees are engaged in multidisciplinary projects involving genetics, biochemistry, and molecular biology. Undergraduates from diverse groups are gaining research experience during the academic year and summer months. A new effort to educate the public is occurring through instructive videos on a website and Youtube channel. Collaboration with a Public Broadcasting Service station is planned to create a professional video explaining the use of synthetic biology to enhance photosynthesis and the role of plants in removing carbon dioxide from the atmosphere. The video is to be made available through PBS Learning Media for K-12 education.C3 crop plants, which constitute approximately 85 percent of plants, including food crops like soybean and wheat, lack the ability to concentrate carbon dioxide near Rubisco. Synthesis of a carbon-concentrating mechanism (CCM) in crop plants, based on ones that exist in cyanobacteria and algae, has the potential to substantially increase yields. Installation of a microcompartment-based CCM requires not only the actual construction of the microcompartment within the chloroplast, but also the provision of additional bicarbonate that can be converted into carbon dioxide. In order to assess whether bicarbonate transporters from microorganisms can function in the chloroplast, their encoding genes are being transformed into a mutant background in which chloroplast carbonic anhydrase has been removed. The absence of carbonic anhydrase in the mutant causes an impaired, bicarbonate-deficient, phenotype that is predicted to be rescued by a functional bicarbonate transporter. The transformed plants are being analyzed not only for the rescue of the bicarbonate-requiring phenotype, but also for effects on photosynthesis, growth, reactive oxygen species, stromal pH, and fatty acid synthesis. In addition to providing an essential step in the transformative engineering of C3 plants with carbon-concentrating mechanisms, modeling predicts that yield can be enhanced by the mere incorporation of inorganic carbon pumps into chloroplasts, even before a full microcompartment-based CCM is installed.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.