Identification and characterisation of microbial interactions in the root microbiome of Medicago truncatula to benefit plant growth

植物寄主和内圈微生物之间的相互作用已被证明对作物生产的几个关键植物性状有重要影响，包括开花物候、对非生物胁迫的耐受性以及营养物质的获得和根的生长。许多豆科植物，如紫花苜蓿，与根瘤菌--固氮菌--形成共生关系，根瘤菌生长在豆科植物根部形成的特殊“根瘤”结构中。这些微生物受益于在结核中获得一席之地以及碳化合物的提供。作为回报，微生物从空气中固定氮素，使其可供植物使用，帮助它们应对土壤氮素利用率低的情况，这可能存在于农业环境中。这些根瘤菌及其与植物的相互作用是当前密集研究的主题，因为管理和加强任何共生都可以(A)增加作物的生长和产量，以及(B)减少全球对使用环境和经济上昂贵的氮肥的依赖。然而，与根瘤菌的共生并不是一种简单或孤立的相互作用--根部微生物群由极其复杂的微生物群落组成。该群落内的相互作用已被证明对植物的整体健康和生长有直接和间接的影响。在这个项目中，我们基于对豆类根瘤根际的初步研究数据，描述了新的微生物伙伴和合作者的特征，这些伙伴和合作者改善了植物的适应性。这些微生物可能会直接或间接地使植物受益。通过扩大我们对土壤微生物体内发生的复杂相互作用的理解，我们可以更好地应用这些知识，进一步探索植物生长促进策略的多样性。

Interactions between plant hosts and microbes in the endosphere have been demonstrated to have significant effects on several key plant traits for crop production including flowering phenology, tolerance to abiotic stress as well as nutrient acquisition and root growth. Many legumes, such as Medicago truncatula, form symbioses with rhizobia - nitrogen fixing bacteria - which are housed in specific 'nodule' structures that form in the roots of the legume. These microbes benefit from gaining a niche within the nodule as well as from the provision of carbon compounds. In return, the microbes fix nitrogen from the air, making it available for the plant, helping them cope with low soil nitrogen availability, such that might be present in an agricultural situation. These rhizobia and their interactions with the plant are a topic of intense current research since managing and enhancing any symbiosis could(a) increase the growth and yields of crops as well as (b) reduce global dependence for the use of environmentally and economically expensive nitrogen fertilisers.Symbiosis with rhizobia however is not a simple or isolated interaction - the root microbiome consists of an extremely complex microbial community. Interactions within this community have been shown to have both direct and indirect effects on the overall health and growth of the plant. In this project we characterise new microbial partners and co-operators which improve plant fitness, based on preliminary data from study of the rhizosphere of nodulating legumes. These microbes may benefit the plant directly or indirectly. By expanding our understanding of the complex interactions that occur within the soil microbiome we can better apply this knowledge further explore the diversity of plant growth-promoting strategies.