AUTHOR=Maywald Niels Julian , Mang Melissa , Pahls Nathalie , Neumann Günter , Ludewig Uwe , Francioli Davide 

TITLE=Ammonium fertilization increases the susceptibility to fungal leaf and root pathogens in winter wheat

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.946584

DOI=10.3389/fpls.2022.946584

ISSN=1664-462X

ABSTRACT=<p>Nitrogen (N) fertilization is indispensable for high yields in agriculture due to its central role in plant growth and fitness. Different N forms affect plant defense against foliar pathogens and may alter soil–plant-microbe interactions. To date, however, the complex relationships between N forms and host defense are poorly understood. For this purpose, nitrate, ammonium, and cyanamide were compared in greenhouse pot trials with the aim to suppress two important fungal wheat pathogens <italic>Blumeria graminis</italic> f. sp. <italic>tritici</italic> (<italic>Bgt</italic>) and <italic>Gaeumannomyces graminis</italic> f. sp. <italic>tritici</italic> (<italic>Ggt</italic>). Wheat inoculated with the foliar pathogen <italic>Bgt</italic> was comparatively up to 80% less infested when fertilized with nitrate or cyanamide than with ammonium. Likewise, soil inoculation with the fungal pathogen <italic>Ggt</italic> revealed a 38% higher percentage of take-all infected roots in ammonium-fertilized plants. The bacterial rhizosphere microbiome was little affected by the N form, whereas the fungal community composition and structure were shaped by the different N fertilization, as revealed from metabarcoding data. Importantly, we observed a higher abundance of fungal pathogenic taxa in the ammonium-fertilized treatment compared to the other N treatments. Taken together, our findings demonstrated the critical role of fertilized N forms for host–pathogen interactions and wheat rhizosphere microbiome assemblage, which are relevant for plant fitness and performance.</p>