Collaborative Research: TRTech-PGR TRACK: Discovery and characterization of small CRISPR systems for virus-based delivery of heritable editing in plants.

鉴于目前的作物生产力预测，农业实践将不足以满足未来的全球粮食需求。人类解决这一问题的能力将在很大程度上取决于创造新的遗传多样性并将其引入植物育种计划的效率。新的基因组编辑技术可以更精确地介绍遗传多样性，但目前的方法非常缓慢和低效，而且只在一些作物物种中有效。该项目旨在发现可以更广泛和快速地在多种作物品种中部署的新型基因组编辑系统，以加强植物育种，使作物具有更高的产量和对干旱、虫害和极端温度的抗性。这些新工具也将对那些没有得到植物生物技术行业足够重视的孤儿作物物种有用。该项目还将包括一种结构化的方法，通过加州大学洛杉矶分校和加州大学伯克利分校两个参与校区的不同项目，让来自不同背景的本科生研究人员参与进来。该项目还将使该项目的博士后和研究生获得培训来自不同背景的学生的经验。基因组编辑技术的最新进展将通过允许精确引入重要植物基因的特定变化来加快植物育种计划。尽管取得了这一进展，但主要的瓶颈仍然存在：快速有效地将基因编辑试剂输送到农作物中。最常见的传递方法是在转基因中编码RNA引导的基因组编辑程序(例如CRISPR-Cas酶)，并使用组织培养和转化方法，或者将CRISPR蛋白直接导入植物细胞，然后进行组织培养以再生植株。然而，组织培养方法需要相当长的时间、资源和技术专长，并可能导致基因组和表观基因组的意外变化。此外，通过组织培养再生植株只适用于有限数量的植物种类和基因类型。植物病毒是将CRISPR系统传递到整个植物的理想载体，而不需要使用植物转化或组织培养。然而，大多数病毒的载货能力很小，不足以容纳目前使用的CRISPR系统。我们建议发现和表征超紧凑的CRISPR系统，这些系统足够小，可以在植物病毒中编码，以便容易和快速地编辑整个植物，这可以用于广泛的重要作物物种。我们将从元基因组学数据中筛选出大量的候选紧凑型基因编辑系统，并在细菌细胞和植物细胞中测试这些系统。目标将是找到与当前大型系统的效率相匹配或超过的超紧凑型编辑系统。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Given current crop productivity projections, agricultural practices will be inadequate to meet future global food demands. Humanity’s ability to address this problem will largely depend on the efficiency with which novel genetic diversity can be created and introduced into plant breeding programs. New genome editing techniques allow for a more precise introduction of genetic diversity, but the current methods are very slow and inefficient and only work in some crop species. This project aims to discover novel genome editing systems that can be more widely and quickly deployed in a large variety of crop species, to enhance plant breeding to make crops with higher yields and resistance to drought, pests, and extreme temperatures. The new tools will also be useful for orphan crop species that do not receive sufficient attention from the plant biotechnology industry. The project will also include a structured approach to involving undergraduate student researchers from diverse backgrounds through different programs at the two participating University of California campuses, UCLA and UC Berkeley. The project will also enable postdocs and graduate students on the project to gain experience in training students from diverse backgrounds.Recent progress in genome editing technology is poised to accelerate plant breeding programs by allowing for the precise introduction of specific changes to important plant genes. Despite this advance, a primary bottleneck remains: fast and effective delivery of the gene editing reagents into crop plants. The most common methods of delivery are to encode RNA-guided genome editors (e.g. CRISPR-Cas enzymes) within transgenes and use tissue culture and transformation approaches or to introduce CRISPR protein and guide RNAs directly into plant cells followed by tissue culture to regenerate plants. However, tissue culture methods require considerable time, resources, and technical expertise, and can cause unintended changes to the genome and epigenome. Furthermore, regenerating plants from tissue culture only works in a limited number of plant species and genotypes. Plant viruses are ideal vectors for the delivery of CRISPR systems to whole plants without the use of plant transformation or tissue culture. However, most viruses have a very small cargo capacity, which is insufficient to accommodate currently used CRISPR systems. We propose to discover and characterize hypercompact CRISPR systems that are small enough to be encoded in plant viruses for easy and fast editing of whole plants, which could be used in a wide range of important crop species. We will screen a large number of candidate compact gene editing systems from metagenomics data and test these systems in bacterial cells and plant cells. The goal will be to find hypercompact editing systems that match or exceed the efficiency of current large systems.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.