Back

Engineering auxin degradation into root-associated bacteria promotes plant growth

Jiang, T.; Shen, Y.; Li, X.; Zhou, Y.; Kozlowski, M. J.; Jeffrey, P. D.; Groves, J. T.; Rabinowitz, J.; Conway, J. M.

2026-08-21 microbiology
10.1101/2025.10.25.684584 bioRxiv
Show abstract

Overproduction of indole-3-acetic acid (IAA) by rhizosphere bacteria disrupts plant auxin homeostasis and induces root growth inhibition (RGI). Variovorax reverses this effect by degrading IAA, but the underlying pathway remains incompletely resolved. Here, using genetics, metabolomics, and isotope tracing, we define a nine-gene region (iadCDEFGHIJK2) required for IAA catabolism in Variovorax paradoxus CL014, identify a previously uncharacterized intermediate (CHNO), and revise the early oxidative steps of the pathway. Although IadDE adopts a Rieske-type oxygenase architecture, our data are consistent with the IadCDE complex functioning as a monooxygenase during IAA degradation. Using these insights, we introduce iad genes into two rhizobacterial chassis, Polaromonas MF047 and Paraburkholderia MF376. These engineered strains degrade IAA and alleviate RGI induced by exogenous IAA, an auxin-producing strain, and a synthetic bacterial community. Engineered Paraburkholderia MF376 delivers the strongest performance, improving plant growth in natural soil. Together, these results establish a framework for engineering auxin-balancing root commensals.

Matching journals

The top 5 journals account for 50% of the predicted probability mass.

50% of probability mass above

"Similar papers" are the closest papers from that journal in the model's embedding space. They show what the match is built on, but the ranking comes mostly from a classifier over the whole training set, not from these examples alone.