The role of nitrogen in plant defence

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.

Effect of NO3 vs. NH4+ on plant resistance to pathogen infection. Growth on NO3 nutrition leads to increased levels of NO, SA, PR gene expression, induction of the polyamine pathway, a decrease in apoplastic sugars and amino acids, and an overall increase in plant resistance in a concentration-dependent manner. Growth on NH4+ nutrition leads to increased levels of apoplastic sugars and amino acids, reduced levels of SA and PR gene expression, induction of GABA biosynthesis and reduced plant defence response.

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.


The Annals of Botany Office is based at the University of Oxford.

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