Nitrogen fertilization influences plant-pathogen interactions and elevated levels of nitrogen can promote susceptibility against biotrophs as well as can influence in plant resistance. The disruption of an ammonium transporter involved in the plant immune system, the ammonium transporter AMT1.1, alters basal defenses generating resistance against Pseudomonas syringae and Plectosphaerella cucumerina (Pastor et al., 2014a). In this work their authors study the role of this ammonium transporter on the basal defenses and the resistance against P. syringae and P. cucumerina demonstrating that it is a negative regulator of Arabidopsis defense responses (Pastor et al., 2014a).