Tiny organisms such as bacteria and fungi help to promote the health and function of plant roots. It is commonly assumed that the composition of these microbes is dependent on the properties of the soil. However, an international team of researchers led by the University of Bonn has now discovered when studying different local varieties of maize that the genetic makeup of the plants also helps to influence which microorganisms cluster around the roots. The results, which have now been published in the prestigious journal Nature Plants, could help to breed future varieties of maize that are better suited to drought and limited nutrients.