Browsing by Subject "Blumeria graminis"

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Ammonium fertilization increases the susceptibility to fungal leaf and root pathogens in winter wheat
(2022) Maywald, Niels Julian; Mang, Melissa; Pahls, Nathalie; Neumann, Günter; Ludewig, Uwe; Francioli, Davide
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 Blumeria graminis f. sp. tritici (Bgt) and Gaeumannomyces graminis f. sp. tritici (Ggt). Wheat inoculated with the foliar pathogen Bgt was comparatively up to 80% less infested when fertilized with nitrate or cyanamide than with ammonium. Likewise, soil inoculation with the fungal pathogen Ggt 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.
Genome-wide association study for resistances to yellow rust, powdery mildew, and Septoria tritici blotch in cultivated emmer
(2024) Miedaner, T.; Afzal, M.; Longin, C. F.
Emmer is a progenitor of bread wheat and evolved in the Levant together with the yellow rust (YR), powdery mildew (PM) fungi, and a precursor of Zymoseptoria tritici causing Septoria tritici blotch (STB). We performed a genome-wide association mapping for the three disease resistances with 143 cultivated emmer accessions in multi-environmental trials. Significant (P < 0.001) genotypic variation was found with high heritabilities for the resistances to the two biotrophs and a moderate heritability for STB resistance. For YR, PM, and STB severity nine, three, and seven marker-trait associations, respectively, were detected that were significant across all environments. Most of them were of low to moderate effect, but for PM resistance a potentially new major gene was found on chromosome 7AS. Genomic prediction abilities were high throughout for all three resistances (≥ 0.8) and decreased only slightly for YR and PM resistances when the prediction was done for the second year with the first year as training set (≥ 0.7). For STB resistance prediction ability was much lower in this scenario (0.4). Despite this, genomic selection should be advantageous given the large number of small QTLs responsible for quantitative disease resistances. A challenge for the future is to combine these multiple disease resistances with better lodging tolerance and higher grain yield.