Nitrogen nutrition modifies the susceptibility of Arabidopsis thaliana to the necrotrophic fungus, Alternaria brassicicola Article - Janvier 2022

Thibault Barrit, Alexis Porcher, Caroline Cukier, Pascale Satour, Thomas Guillemette, Anis Limami, Béatrice Teulat, Claire Campion, Elisabeth Planchet

Thibault Barrit, Alexis Porcher, Caroline Cukier, Pascale Satour, Thomas Guillemette, Anis Limami, Béatrice Teulat, Claire Campion, Elisabeth Planchet, « Nitrogen nutrition modifies the susceptibility of Arabidopsis thaliana to the necrotrophic fungus, Alternaria brassicicola  », Physiologia Plantarum, janvier 2022, e13621. ISSN 0031-9317

Abstract

The impact of the form of nitrogen (N) source (nitrate versus ammonium) on thesusceptibility toAlternaria brassicicola, a necrotrophic fungus, has been examined inArabidopsis thalianaat the rosette stage. Nitrate nutrition was found to increase fungallesions considerably. There was a similar induction of defence gene expression followinginfection under both N nutritions, except for thephytoalexin deficient 3gene, which wasoverexpressed with nitrate. Nitrate also led to a greater nitric oxide production occurringin plantaduring the saprophytic growth and lower nitrate reductase (NIA1) expression7 days after inoculation. This suggests thatnitrate reductase-dependent nitric oxideproduction had a dual role, whereby, despite its known role in the generic response topathogens, it affected plant metabolism, and this facilitated fungal infection. Inammonium-grown plants, infection withA. brassicicolainduced a stronger gene expressionof ammonium transporters and significantlyreduced the initially high ammonium contentin the leaves. There was a significant interaction between N source and inoculation (pres-ence versus absence of the fungus) on the total amino acid content, while N nutrition rec-onfigured the spectrum of major amino acids.Typically, a higher content of total aminoacid, mainly due to a stronger increase in asparagine and glutamine, is observed underammonium nutrition while, in nitrate-fed plants, glutamate was the only amino acid whichcontent increased significantly after fungalinoculation. N nutrition thus appears to controlfungal infection via a complex set of signalling and nutritional events, shedding light onhow nitrate availability can modulate disease susceptibility.

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