Genetic code expansion enables plant-directed control of bacterial activity

Programmable control of microbial gene expression by plant hosts could enable a new generation of precision agricultural biotechnology. Here, using O-methyl-L-tyrosine (OMY) as a model compound, we establish non-standard amino acids (nsAA) as a platform for plant-based control of associated microbial activity. We use genetic code expansion to engineer OMY-dependent control of protein synthesis in the soil bacterium Bacillus subtilis. Then, we engineer agronomically diverse plants, including Arabidopsis, tomato and poplar, to biosynthesize OMY. We show that plant-derived OMY can stimulate gene expression in both model and wild soil bacteria and demonstrate how inducible and tissue-specific expression of a single biosynthetic enzyme by the plant enables tight, on-demand control over microbial activity. This work establishes nsAAs as a tool for programming plant-microbe partnerships.