Castellani Lucas G, Luchetti Abril, Nilsson Juliet F, Pérez-Giménez Julieta, Wegener Caren, Schlüter Andreas, Pühler Alfred, Lagares Antonio, Brom Susana, Pistorio Mariano, Niehaus Karsten, Torres Tejerizo Gonzalo A
Instituto de Biotecnología y Biología Molecular (IBBM), CCT-La Plata, CONICET, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina.
CeBiTec, Bielefeld University, Bielefeld, Germany.
Front Plant Sci. 2021 Feb 10;12:642576. doi: 10.3389/fpls.2021.642576. eCollection 2021.
One of the greatest inputs of available nitrogen into the biosphere occurs through the biological N-fixation to ammonium as result of the symbiosis between rhizobia and leguminous plants. These interactions allow increased crop yields on nitrogen-poor soils. Exopolysaccharides (EPS) are key components for the establishment of an effective symbiosis between alfalfa and , as bacteria that lack EPS are unable to infect the host plants. LPU83 is an acid-tolerant rhizobia strain capable of nodulating alfalfa but inefficient to fix nitrogen. Aiming to identify the molecular determinants that allow to infect plants, we studied its EPS biosynthesis. LPU83 produces an EPS I identical to the one present in , but the organization of the genes involved in its synthesis is different. The main gene cluster needed for the synthesis of EPS I in , is split into three different sections in , which probably arose by a recent event of horizontal gene transfer. A strain devoided of all the genes needed for the synthesis of EPS I is still able to infect and nodulate alfalfa, suggesting that attention should be directed to other molecules involved in the development of the symbiosis.
生物圈内可用氮的最大输入之一是通过根瘤菌与豆科植物共生将氮生物固定为铵而实现的。这些相互作用能提高贫氮土壤上的作物产量。胞外多糖（EPS）是苜蓿与[具体细菌名称缺失]建立有效共生关系的关键成分，因为缺乏EPS的细菌无法感染宿主植物。LPU83是一种耐酸根瘤菌菌株，能够使苜蓿结瘤，但固氮效率低下。为了确定使[具体细菌名称缺失]能够感染植物的分子决定因素，我们研究了其EPS生物合成。LPU83产生的EPS I与[具体细菌名称缺失]中存在的EPS I相同，但其合成相关基因的组织方式不同。在[具体细菌名称缺失]中合成EPS I所需的主要基因簇在LPU83中被分成三个不同的部分，这可能是最近水平基因转移事件导致的。一个缺失了合成EPS I所需所有基因的[具体细菌名称缺失]菌株仍然能够感染苜蓿并使其结瘤，这表明应该关注参与共生关系发展的其他分子。
