Walking down the phosphorylation path to root immunity.

Pathogen perception in plant roots is under-explored compared to that in shoots. In this issue of Cell Host & Microbe, Wang et al. characterize the phosphorylation-mediated signaling pathway that positively and negatively regulates plant resistance to bacterial wilt disease upon perception of a metabolite from the soil-borne vascular pathogen Ralstonia solanacearum.