The form of nitrogen nutrition affects resistance against Pseudomonas syringae pv. phaseolicola in tobacco

Kapuganti J. Gupta, Yariv Brotman, Shruthi Segu, Tatiana Zeier, Jürgen Zeier, Stefan T Persijn, Simona M. Cristescu, Frans J M Harren, Hermann Bauwe, Alisdair R. Fernie, Werner M Kaiser, Luis A J Mur

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108 Citations (SciVal)


Different forms of nitrogen (N) fertilizer affect disease development; however, this study investigated the effects of N forms on the hypersensitivity response (HR)-a pathogen-elicited cell death linked to resistance. HR-eliciting Pseudomonas syringae pv. phaseolicola was infiltrated into leaves of tobacco fed with either NO₃⁻ or NH₄⁺. The speed of cell death was faster in NO₃⁻-fed compared with NH₄⁺-fed plants, which correlated, respectively, with increased and decreased resistance. Nitric oxide (NO) can be generated by nitrate reductase (NR) to influence the formation of the HR. NO generation was reduced in NH₄⁺-fed plants where N assimilation bypassed the NR step. This was similar to that elicited by the disease-forming P. syringae pv. tabaci strain, further suggesting that resistance was compromised with NH₄⁺ feeding. PR1a is a biomarker for the defence signal salicylic acid (SA), and expression was reduced in NH₄⁺-fed compared with NO₃⁻ fed plants at 24h after inoculation. This pattern correlated with actual SA measurements. Conversely, total amino acid, cytosolic and apoplastic glucose/fructose and sucrose were elevated in - treated plants. Gas chromatography/mass spectroscopy was used to characterize metabolic events following different N treatments. Following NO₃⁻ nutrition, polyamine biosynthesis was predominant, whilst after NH₄⁺ nutrition, flux appeared to be shifted towards the production of 4-aminobutyric acid. The mechanisms whereby feeding enhances SA, NO, and polyamine-mediated HR-linked defence whilst these are compromised with NH₄⁺, which also increases the availability of nutrients to pathogens, are discussed.
Original languageEnglish
Pages (from-to)553-568
Number of pages16
JournalJournal of Experimental Botany
Issue number2
Early online date10 Dec 2012
Publication statusPublished - 2013


  • ammonium
  • hypersensitive response
  • nitrate
  • nitric oxide
  • paseudomonas
  • tobacco


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