How legumes create an environment for nitrogen fixation: control of oxygen permeation into nodules

豆科植物如何创造固氮环境：控制氧气渗透到根瘤中

• 批准号: 325528135
• 负责人: Professorin Dr. Macarena Marin
• 金额: --
• 依托单位: Département de biologie moléculaire végétale
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/325528135?language=en
• 关键词: How; legumes; create; environment; nitrogen

Legumes host symbiotic rhizobia inside root structures called nodules where they create an environment suitable for nitrogen fixation. Understanding how this environment emerges is critical for optimizing this symbiosis in legumes and engineering nodulation in other crops. In the first funding period we explored the natural diversity of the symbiotic phenotypes of Lotus using comparative transcriptomics. Thereby we identified genes that were specifically upregulated in infected nodules and thus might mediate the accommodation of rhizobia inside these structures. Phylogenetic and expression analysis of two nodule induced suberin biosynthesis genes encoding Fatty acyl-CoA reductases (FARs) revealed diversification in their expression pattern. Spatiotemporal analysis of promoter activity controlling the expression of these and other suberin-related genes showed distinct activation in the root and nodule endodermis. Mutant lines in the nodule specific FAR3.2 gene, showed an increase in nodule permeability, impaired nitrogen fixation, and reduced shoot growth. Our results support a model in which nodule-specific suberin related genes mediate the formation of a permeation barrier in the nodule periphery. The control of oxygen permeation into the nodule is essential to protect the oxygen-sensitive nitrogenase and is thus crucial for nitrogen fixation. In this project we will investigate the function and regulation of genes with suberin-related functions, as they are promising molecular markers for the establishment of the nodule barrier, which controls oxygen permeation. To this end we will create mutant lines by CRISPR/Cpf1 gene editing and phenotypically characterize them, we will generate reporter lines to determine the ontogeny of the nodule barrier, and will investigate the regulation of suberin-related genes at a molecular level. This work will advance our understanding of how the nodule barrier is formed, a key adaptation enabling nitrogen fixation in legumes.

豆科植物在称为根瘤的根部结构中寄生共生根瘤菌，在那里它们创造了适合固氮的环境。了解这种环境是如何出现的，对于优化豆类的这种共生关系和在其他作物中进行工程结瘤至关重要。在第一个资助期，我们用比较转录组学的方法探索了莲花共生表型的自然多样性。因此，我们确定了在受感染的根瘤中特异上调的基因，从而可能调节根瘤菌在这些结构中的适应。对编码脂肪酰辅酶A还原酶(FARS)的两个根瘤诱导大豆黄酮素生物合成基因的系统发育和表达分析表明，它们的表达模式存在多样性。对控制这些基因和其他Suberin相关基因表达的启动子活性的时空分析表明，在根和根瘤内胚层中有明显的激活。根瘤特异的FAR3.2基因突变系表现出根瘤透性增加，固氮作用减弱，新梢生长减慢。我们的结果支持一个模型，在该模型中，根瘤特异性suberin相关基因介导了根瘤外围渗透屏障的形成。控制氧渗入根瘤是保护对氧敏感的固氮酶的关键，因此对固氮至关重要。在这个项目中，我们将研究具有suberin相关功能的基因的功能和调控，因为它们是建立控制氧渗透的根瘤屏障的有希望的分子标记。为此，我们将通过CRISPR/Cpf1基因编辑建立突变系并对其进行表型鉴定，我们将产生报告系来确定根瘤屏障的个体发育，并将在分子水平上研究suberin相关基因的调控。这项工作将促进我们对根瘤屏障是如何形成的理解，这是实现豆类固氮的关键适应。