Engineering Rhizobacteria for Biological Nitrogen Fixation in Cereals

全球人口的增加给粮食生产力和安全带来了更大的负担。培育新作物品种是为了获得更高的产量和抗虫性，但它们仍然需要施肥来供应土壤中通常有限的氮素。土壤中的固氮菌为减少农业对工业生产的无机肥料的依赖提供了机会，无机肥料污染地下水并释放出强有力的温室气体N2O。但目前生物固氮主要局限于豆科植物，需要复杂的双向信号和生理变化才能与固氮根瘤菌建立共生关系。根瘤菌定植所需的特性知之甚少，因此很难推广到谷类作物。我们的目标是利用谷物内生植物，如多功能氮素固定剂azorhizobium caulinodans，作为底盘来设计和增强谷物的生物固氮和向宿主释放氨的能力。人工合成的正交越界信号将被用来建立谷物和根际细菌之间的植物-微生物相互作用，并控制固氮和其他植物生长促进性状的工程微生物。

An increasing global population puts a greater burden on food productivity and security. Newcrop varieties are being bred for greater yield and pest resistance, however they still requirefertilisation to supply nitrogen which is normally limited in the soil. Nitrogen fixing bacteria inthe soil provide an opportunity to reduce the dependency of agriculture on in-organic fertiliserproduced by industry, which pollute ground water and release the potent greenhouse gas N2O.However, biological nitrogen fixation is currently mainly limited to legumes which requirecomplex two-way signalling and physiological changes to establish symbiosis with nitrogen fixingrhizobia. The traits required for colonisation by rhizobia are poorly understood and thereforedifficult to extend to cereal crops. Our aim is to use cereal endophytes, such as the versatilenitrogen fixer Azorhizobium caulinodans, as a chassis to engineer and enhance biologicalnitrogen fixation and ammonia release to the host in cereals. A synthetic orthogonal transkingdom signal will be used to establish a plant-microbe interaction between cereals andrhizobacteria and control nitrogen fixation and other plant growth promoting traits inengineered microbes.