RESEARCH-PGR: Functional Genomics of Beneficial Legume-microbe Interactions

豆类作物是人类食物、牲畜饲料和工业原料的主要来源。 豆类是可持续农业系统不可或缺的一部分，因为它与称为根瘤菌的细菌共生固氮，每年向这种系统注入5 000万吨固定氮。豆科植物还与土壤真菌形成有益的丛枝菌根共生体，这增强了土壤磷和其他养分的获得。这两种共生体使生产性植物栽培能够使用更少的肥料，从而减少农业对环境的影响。 该项目以豆科植物蒺藜苜蓿为重点，将确定与细菌和/或真菌共生所需的关键植物基因，并促进我们对农业中最重要的两种植物-微生物共生关系的理解。该项目汇集了来自五个州的六个研究和教学机构的七个研究小组，形成了一个世界级的豆类共生研究虚拟中心，将产生巨大的协同作用，并在基因组学，生物信息学和其他学科提供优秀的跨学科培训机会。培训将提供从博士后研究人员，研究生到本科生的职业水平，目的是发展成功的科学职业所需的技能。该项目的外联部分将使高中生、普通公众中的成年人和儿童参与教育和有趣的科学体验。 通过帮助培养下一代科学家和帮助使农业更可持续和环境友好，拟议的活动将造福社会。豆科植物是可持续农业系统不可或缺的组成部分，因为豆科植物与称为根瘤菌的细菌共生固氮（SNF），与土壤真菌有益的丛枝菌根（AM）共生，提高土壤磷和其他养分的获得。尽管通过转录组研究，成千上万的植物基因与这些共生体相关，但大多数这些基因的共生作用和重要性仍不清楚。 本项目以豆科植物蒺藜苜蓿为研究对象，利用现有的大量Tnt 1转座子插入突变体群体，对SNF和AM共生的功能基因组学进行研究。在全基因组无偏正向遗传筛选中，已经鉴定出190个具有新的Nod+Fix-或调节表型的Tnt 1插入突变体。新的序列捕获技术将加速因果突变的鉴定，从而能够鉴定参与固氮和自动调节的新基因。功能基因组学活动，使一个大的Tnt 1突变体人口和索引侧翼序列标签资源将集中在转运蛋白参与营养物质运输过程中根瘤菌和AM共生。通过CRISPR-Cas9基因组编辑产生的Tnt 1突变体和突变体的组合将用于研究先前通过比较基因组学方法鉴定的AM共生保守的一组138个基因。总之，这些活动将确定关键的共生基因，并促进我们对可持续农业至关重要的两种植物-微生物共生的理解。

Legume crops are a primary source of food for humans, feed for livestock, and raw materials for industry. Legumes are integral to sustainable agricultural systems by virtue of symbiotic nitrogen fixation with bacteria called rhizobia, which injects 50 million tons of fixed-nitrogen into such systems annually. Legumes also form beneficial arbuscular mycorrhizal symbioses with soil fungi, which enhance the acquisition of soil phosphorous and other nutrients. These two symbioses enable productive plant cultivation with less fertilizer, which reduces the environmental impact of agriculture. Focusing on the legume species, Medicago truncatula this project will identify key plant genes required for symbiosis with bacteria and/or fungi and advance our understanding of what are arguably the two most important plant-microbe symbioses in agriculture. This project brings together seven research groups from six research and teaching institutions in five states to form a world-class, virtual center for legume symbiosis research that will generate great synergy and provide outstanding trans-disciplinary training opportunities in genomics, bioinformatics and other disciplines. Training will be provided at career levels ranging from postdoctoral researchers, graduate students, to undergraduate students with the aim of developing skillsets necessary for successful scientific careers. Outreach components of this project will engage high & middle school students, adults in the general public and children in educational and fun scientific experiences. The proposed activities will benefit society by helping to train the next generation of scientists and by helping to make agriculture more sustainable and environmentally-friendly.Legumes are integral to sustainable agricultural systems by virtue of symbiotic nitrogen fixation (SNF) with bacteria called rhizobia, and beneficial arbuscular mycorrhizal (AM) symbioses with soil fungi that enhance the acquisition of soil phosphorous and other nutrients. Although thousands of plant genes have been associated with these symbioses via transcriptome studies, the symbiotic role and importance of most of these genes remain unclear. Focusing on the legume, Medicago truncatula this project will take advantage of a very large existing Tnt1 transposon-insertion mutant population for functional genomics of SNF and AM symbiosis. One hundred and ninety Tnt1 insertion mutants with novel Nod+Fix- or regulatory phenotypes have already been identified in a genome-wide non-biased forward genetic screen. New sequence-capture technologies will accelerate the identification of the causal mutations enabling the identification of new genes involved in nitrogen fixation and autoregulation of nodulation. Functional genomics activities, enabled by a large Tnt1 mutant population and indexed flanking sequence tag resource will focus on transporter proteins involved in nutrient transport during rhizobial and AM symbioses. A combination of Tnt1 mutants and mutants generated through CRISPR-Cas9 genome editing will be used to investigate a set of 138 genes conserved for AM symbiosis identified previously through a comparative phylogenomics approach. Together, these activities will identify key symbiotic genes and advance our understanding of two plant-microbe symbioses that are crucial for sustainable agriculture.