Plants need nitrogen (N) for growth, development and defence against abiotic and biotic stresses. The widespread use of artificial N fertilisers and the agricultural impact of N nutrition on disease development have been extensively examined. In this review article, Mur et al. show that NO3– or NH4+ fertilisers affect the outcome of plant–pathogen interactions.
They find NO3– feeding augments hypersensitive response (HR) mediated resistance, whilst ammonium nutrition can compromise defence. Metabolically, NO3– enhances production of polyamines such as spermine and spermidine defence signals, whilst NH4+ nutrition leads to increased γ-aminobutyric acid (GABA) levels which may be a nutrient source for the pathogen.
This paper is part of the Annals of Botany Special Issue on Plant Immunity. It will be free access till June 2017 and after April 2018.