Stuck on you: Bacterial-auxin-mediated bacterial colonization of plant roots

Auxin secreted by root-associated bacteria promotes plant growth, yet benefits to bacteria themselves are ill-defined. In this issue of Cell Host & Microbe, Tzipilevich et al. (2021) demonstrate that auxin and plant EFR-triggered response are essential for root colonization of B. velezensis, indicating potential co-evolution of plants and root commensal bacteria.