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Environmental Science and Engineering Seminar

Wednesday, June 4, 2025
4:00pm to 5:00pm
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South Mudd 365
Understanding and Engineering Plant-Microbe Interactions for Sustainable Agriculture
Gozde Demirer, Chemistry and Chemical Engineering, Caltech,

Plant growth-promoting rhizobacteria (PGPR) can improve crop yields and increase plant tolerances to a variety of stresses. This makes plant microbiome engineering a compelling strategy in the on-going efforts to provide food security and combat impacts of climate change. However, a long-standing challenge in deploying microbial solutions for agriculture is achieving stable plant colonization and long-term persistence in soils, particularly for non-native or engineered microbes. Our lab is taking a two-pronged approach to plant microbiome engineering, both through improving rhizobacteria to better support plants under stress and plant host engineering to strengthen symbiotic relationships.

For our plant host engineering approach, we focused on understanding how plant-derived carbon sources shape soil microbiome composition and function. By screening root exudates and other carbon substrates, we identified selective carbon sources that preferentially support the growth of beneficial rhizobacteria. Using our high-throughput microbial enrichment assays, we demonstrated that application of these compounds can selectively increase the abundance and persistence of target PGPR species in agricultural soils with native microbiome. This microbial enrichment improved the performance of Arabidopsis thaliana plants under nutrient and water stress. Building on these findings, we are engineering plants to secrete these beneficial carbon compounds directly into the rhizosphere in a spatiotemporally controlled manner, constructing plants capable of recruiting designer microbiomes.

In parallel, we are engineering rhizobacteria themselves. In one project, we modified Bacillus subtilis biofilms to incorporate proteins that enhance water retention at the root-soil interface under osmotic stress. We found that several of these engineered strains successfully colonized roots, persisted in the rhizosphere, and improved the osmotic stress tolerance of Arabidopsis plants. Approaching plant microbiome engineering through both the host and microbial community offers a holistic strategy to enhance plant resilience and productivity to support sustainable agriculture efforts.

For more information, please contact Bronagh Glaser by email at bglaser@caltech.edu or visit Environmental Science and Engineering.