Plant roots are colonized by billions of microorganisms that affect plant growth and tolerance to (a)biotic stresses. Recently we discovered that plants infected by fungal pathogens actively recruit microbes inside their root tissue, the endosphere, for protection. Here we will investigate how plants under siege communicate with their microbiome and characterize the protective endophytic microbes, their genes and metabolites. With nano-microscopic techniques we will unwire where microbes live inside plant roots and express their protective traits. The obtained fundamental knowledge will provide a strong basis for developing innovative strategies that integrate microbiomes in plant breeding and sustainable crop protection.