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

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.