(544g) Invited Talk: Engineering Rhizosphere Commensals to Promote Auxin Homeostasis and Enhance Plant Growth

Plant-microbe interactions in the rhizosphere have large impacts on plant growth, health, and resilience. Despite their importance, the molecular and genetic mechanisms that govern these interactions are not well understood. Auxins are key plant hormones that regulate root development, and microbes in the rhizosphere both produce and degrade auxins.

In previous work, we identified a conserved indole-3-acetic acid (IAA) auxin degradation locus in Variovorax that plays a central role in maintaining auxin homeostasis and supporting normal root development in the context of the microbiome. Building on this understanding, we are engineering plant-associated commensal bacteria with components of the IAA degradation locus to confer the ability to degrade auxin in other genera. Plants treated with these engineered strains show improved growth phenotypes. In addition, we are investigating how these engineered strains colonize the plant host compared to their unengineered parent strains, and the role of this strain engineering in shaping microbial community dynamics.

Together, this work provides new mechanistic insight into how auxin influences plant microbiome dynamics and informs strategies to engineer and apply rhizosphere commensal bacteria to support plant growth. Our findings highlight the potential of engineered rhizosphere microbiota as biotechnologies for sustainable agriculture.