The rhizosphere is a rich and dynamic area at the soil–plant root interface that hosts various pathogenic and beneficial microorganisms. Beneficial non-symbiotic rhizobacteria, such as Bacillus spp., confer multiple advantageous properties to plants that include stress tolerance, regulation of plant development, enhanced nutrient availability and protection against soil pathogens. These bacteria need to efficiently colonize the root, and the success of this partially depends on the availability of mineral nutrients such as iron. Iron is important for plant growth and defence, but it is also used by phytopathogens to cause infection. Rhizobacteria can enhance plant iron uptake to help control infections and use this element to colonize plant roots. The key machineries involved in such plant-associated bacterial interactions are secretion systems. Bacillus spp., for example, express the type VII secretion system (T7SS), but its function in the context of plant–microorganism interactions is unknown. In this study, Liu and colleagues show that the T7SS of the rhizobacterium Bacillus velezensis SQR9 secretes the effector protein YukE to cause iron leakage in plant roots and support root colonization.