title: Clubroot resistance QTL are modulated by nitrogen input in Brassica napus.
abstract: Nitrogen levels can modulate the effectiveness of clubroot resistance in an isolate- and host-specific manner. While the same QTL were detected under high and low nitrogen, their effects were altered. Clubroot, caused by Plasmodiophora brassicae, is one of the most damaging diseases of oilseed rape and is known to be affected by nitrogen fertilization. However, the genetic factors involved in clubroot resistance have not been characterized under nitrogen-limiting conditions. This study aimed to assess the variability of clubroot resistance under different nitrogen levels and to characterize the impact of nitrogen supply on genetic resistance factors. Linkage analyses and a genome-wide association study were conducted to detect QTL for clubroot resistance and evaluate their sensitivity to nitrogen. The clubroot response of a set of 92 diverse oilseed rape accessions and 108 lines derived from a cross between 'Darmor-bzh' (resistant) and 'Yudal' (susceptible) was studied in the greenhouse under high- and low-nitrogen conditions, following inoculation with the P. brassicae isolates eH and K92-16. Resistance to each isolate was controlled by a major QTL and a few small-effects QTL. While the same QTL were detected under both high and low nitrogen, their effects were altered. Clubroot resistance to isolate eH, but not K92-16, was greater under a low-N supply versus a high-N supply. New sources of resistance were found among the oilseed rape accessions under both low and high-N conditions. The results are discussed relative to the literature and from a crop improvement perspective.
authors.affiliation: IGEPP, AGROCAMPUS OUEST, INRA, Université de Rennes 1, 35650, Le Rheu, France.
authors.forename: A
authors.initials: A
authors.lastname: Laperche
authors.affiliation: IGEPP, AGROCAMPUS OUEST, INRA, Université de Rennes 1, 35650, Le Rheu, France.
authors.forename: Y
authors.initials: Y
authors.lastname: Aigu
authors.affiliation: IGEPP, AGROCAMPUS OUEST, INRA, Université de Rennes 1, 35650, Le Rheu, France.
authors.forename: M
authors.initials: M
authors.lastname: Jubault
authors.affiliation: IGEPP, AGROCAMPUS OUEST, INRA, Université de Rennes 1, 35650, Le Rheu, France.
authors.forename: M
authors.initials: M
authors.lastname: Ollier
authors.affiliation: IGEPP, AGROCAMPUS OUEST, INRA, Université de Rennes 1, 35650, Le Rheu, France.
authors.forename: S
authors.initials: S
authors.lastname: Guichard
authors.affiliation: IGEPP, AGROCAMPUS OUEST, INRA, Université de Rennes 1, 35650, Le Rheu, France.
authors.forename: P
authors.initials: P
authors.lastname: Glory
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, T6G 2P5, Canada.
authors.forename: S E
authors.initials: SE
authors.lastname: Strelkov
authors.affiliation: IGEPP, AGROCAMPUS OUEST, INRA, Université de Rennes 1, 35650, Le Rheu, France.
authors.forename: A
authors.initials: A
authors.lastname: Gravot
authors.affiliation: IGEPP, AGROCAMPUS OUEST, INRA, Université de Rennes 1, 35650, Le Rheu, France. maria.manzanares@agrocampus-ouest.fr.
authors.forename: M J
authors.initials: MJ
authors.lastname: Manzanares-Dauleux
mesh_terms: D029688:Brassica napus / Q000235:genetics* / Q000382:microbiology; D060467:Disease Resistance / Q000235:genetics*; D056726:Genetic Association Studies; D008040:Genetic Linkage; D005838:Genotype; D016014:Linear Models; D009584:Nitrogen / Q000378:metabolism*; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D056909:Plasmodiophorida; D040641:Quantitative Trait Loci
chemical_list: D009584:Nitrogen
keywords: Abiotic and biotic stresses; Genetic diversity; Linkage and GWAS analyses; Multi-stress; Oilseed rape; Plasmodiophora brassicae