(26f) Engineering Plant-Microbe Communication for Sustainable Agriculture

Plant growth-promoting bacteria improve crop yields via the production of plant hormones, increase plant tolerances to a variety of stressors, and protect plants against pathogen threats. This makes plant microbiome engineering a compelling strategy in the on-going efforts to provide food security for a growing population living under changing climate. The community structure and the functional role of the plant microbiome is dictated in part by the secretion of carbon-rich compounds from plant roots known as exudates. These exudates represent the nutritional basis by which the microbiome is built and therefore forms the major communication pathway between the plant host and its microbial inhabitants. Synthetic biology and genome engineering are promising approaches to optimize this communication between plants and their microbiome for sustainable agriculture efforts.

Shifting the structure of the plant root microbiome to support more plant-growth promoting bacteria via exudate engineering requires a detailed understanding of the specific chemical signals mediating colonization of desired bacterial symbionts. To understand the signal exchange involved in plant microbiome assembly, we have developed high-throughput tools for testing bacteria chemotaxis and growth. We are currently elucidating how these chemical signals influence bacterial interspecies competition and community dynamics in agricultural soils via metagenomics sequencing. The next steps of this project will characterize the functionality of the enriched and altered microbiome to confer increased plant nutrient use efficiency, informing future plant breeding and engineering efforts.

In this presentation, I will discuss our approach for disentangling the Arabidopsis thaliana exudate chemicals that specifically recruit and stimulate the colonization of desirable plant-growth promoting bacteria, initially focusing on the phosphate-solubilizing and nitrogen-fixing rhizobacteria. I will discuss our combined synthetic biology approach that integrates bacterial metabolic phenotyping and high-throughput chemotaxis assays, which resulted in the identification of chemical targets with potential to specifically enrich the plant microbiome. Lastly, I will highlight our preliminary metagenomics results informing our future plant exudate engineering efforts.