Biological nitrogen fixation in maize: optimizing nitrogenase expression in a root-associated diazotroph
Biological nitrogen fixation in maize: optimizing nitrogenase expression in a root-associated diazotroph
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DOI：
10.1093/jxb/eraa176
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发表时间：
2020-07-25
影响因子：
6.9
通讯作者：
Temme，Karsten
中科院分区：
文献类型：
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作者：
Bloch，Sarah E.;Clark，Rosemary;Temme，Karsten
植物依赖于根和根相关微生物之间的有益相互作用来促进生长、抑制疾病和养分利用。这包括自由生活的固氮细菌提供氮的能力，这是一种长期以来在现代农业中对高效作物生产系统的生态作用。豆科植物-根瘤菌相互作用的长期生态学研究表明，氮素输入的增加会导致不太合作的固氮互利共生者的进化。在这里，我们描述了如何重新编程的固氮和同化在一个新的根相关固氮生物的遗传调控可以恢复铵生产的存在下，外源氮输入。我们从玉米根中分离了一株植物相关蛋白菌Kosakonia sacchari，表征了其氮调控网络，并针对关键节点进行基因编辑以优化玉米的固氮。虽然野生型菌株在充满生物可利用氮的条件下表现出固氮的抑制，例如施肥温室和田间实验，但改造的菌株在温室和田间的玉米根际中甚至在外源氮的存在下也表现出升高的水平。这些菌株可用于商业应用，为谷类作物提供固定氮。
Plants depend upon beneficial interactions between roots and root-associated microorganisms for growth promotion, disease suppression, and nutrient availability. This includes the ability of free-living diazotrophic bacteria to supply nitrogen, an ecological role that has been long underappreciated in modern agriculture for efficient crop production systems. Long-term ecological studies in legume–rhizobia interactions have shown that elevated nitrogen inputs can lead to the evolution of less cooperative nitrogen-fixing mutualists. Here we describe how reprogramming the genetic regulation of nitrogen fixation and assimilation in a novel root-associated diazotroph can restore ammonium production in the presence of exogenous nitrogen inputs. We isolated a strain of the plant-associated proteobacteriumKosakonia saccharifrom corn roots, characterized its nitrogen regulatory network, and targeted key nodes for gene editing to optimize nitrogen fixation in corn. While the wild-type strain exhibits repression of nitrogen fixation in conditions replete with bioavailable nitrogen, such as fertilized greenhouse and field experiments, remodeled strains show elevated levels in the rhizosphere of corn in the greenhouse and field even in the presence of exogenous nitrogen. Such strains could be used in commercial applications to supply fixed nitrogen to cereal crops.