Rhizosphere and synthetic community ecology

In agriculture, nitrogen limitation is overcome through the application of nitrogen fertiliser. However, rising production costs coupled with its negative environmental impacts have resulted in a drive to seek novel approaches to supply plants with nitrogen. One such approach is to utilise plant associated N2-fixing bacteria, since economically important crops such as cereals lack a rhizobium-legume like symbiosis. These N2-fixing bacteria form part of a larger class of microbes referred to as plant growth promoting rhizobacteria (PGPR). PGPR colonise the rhizosphere of plants, the region of soil influenced by plant roots, and promote plant growth through a number of mechanisms including biological nitrogen fixation, mineral solubilisation, production of phytochromes and pathogen biocontrol. In this context, PGPR are being formulated into biofertilisers for agricultural use. However, this approach has had limited success with plant genotype, environment and microbial community all shown to influence the effectiveness of these biofertilisers. This work aims to expand our current understanding of how these factors interact at the community level to influence the formation of nodule-independent symbioses between PGPR and their host plant. To do this, synthetic communities consisting of bacteria isolated from the rhizospheres of model plant species will be used in colonisation and plant growth promotion assays to assess how changes in community structure and plant species affect the ability of PGPR to colonise and promote the growth of their host. In addition, genetic screens will be used to further characterise the genetic determinants involved in forming and maintaining a stable nodule-independent symbiosis. It is hoped that a greater understanding of this area may aid efforts to enhance the efficiency of these biofertilisers, thereby contributing to sustainability in agriculture as well as global food security.



BBRSC priority areas addressed by this research

Food, Nutrition and Health
Sustainably Enhancing Agricultural Production
Global Food Security

AFS, ENWW