Engineering New Rhizosphere Signalling Circuits in Cereals

Rhizosphere microbiome significantly influence host plant health and fitness in natural environments. Host plants reported to exude approximately 20% of their photosynthesized carbon as simple organic molecules in roots vicinity to recruit and shape its rhizosphere communities from the reservoir of microbes in soil. We aim to engineer synthetic plant to microbe signalling circuits in rhizosphere to control gene expression in rhizobacteria for delivering beneficial traits to host plants.

Rhizopines are aminocyclitol compounds produced by a few rhizobial strains in legume nodules and secreted into rhizosphere. By activating its own catabolism genes in free-living rhizobia, rhizopines provide a nutritional advantage to them during competition with other saprophytic microorganisms in rhizosphere.

I will be presenting our work on engineering rhizopine biosynthetic pathway into cereals and demonstrate the cross-kingdom signalling established between rhizopine producing transgenic plants and engineered bacteria (Geddes et. al 2019). Rhizopine mediated synthetic trans-kingdom signalling will enable host cereal plants to control diverse metabolism in root associated bacteria. Future work in our lab focus on using rhizopine signalling to control nitrogen fixation, phosphate solubilisation and anti-fungal metabolite production in rhizobacteria and deliver useful functions for plants.

1. Geddes B, Paramasivan P, Joffrin A, et. al. (2019) Nat Commun. 10:3430

2. Geddes et. al. (2014) Curr. Opin. Biotechnol. 32: 216-222.

UK-BBSRC and US-NSF joint funding support this work.