title: Nitrogen modulation of Medicago truncatula resistance to Aphanomyces euteiches depends on plant genotype.
abstract: Nitrogen (N) availability can impact plant resistance to pathogens by the regulation of plant immunity. To better understand the links between N nutrition and plant defence, we analysed the impact of N availability on Medicago truncatula resistance to the root pathogen Aphanomyces euteiches. This oomycete is considered to be the most limiting factor for legume production. Ten plant genotypes were tested in vitro for their resistance to A. euteiches in either complete or nitrate-deficient medium. N deficiency led to enhanced or reduced susceptibility depending on the plant genotype. Focusing on four genotypes displaying contrasting responses, we determined the impact of N deficiency on plant growth and shoot N concentration, and performed expression analyses on N- and defence-related genes, as well as the quantification of soluble phenolics and different amino acids in roots. Our analyses suggest that N modulation of plant resistance is not linked to plant response to N deprivation or to mechanisms previously identified to be involved in plant resistance. Furthermore, our studies highlight a role of glutamine in mediating the susceptibility to A. euteiches in M. truncatula.
authors.affiliation: Agroécologie, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, Dijon, France.
authors.forename: Elise
authors.initials: E
authors.lastname: Thalineau
authors.affiliation: Agroécologie, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, Dijon, France.
authors.forename: Carine
authors.initials: C
authors.lastname: Fournier
authors.affiliation: Université Rennes 1, UMR 1349 IGEPP, Rennes, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Gravot
authors.affiliation: Agroécologie, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, Dijon, France.
authors.forename: David
authors.initials: D
authors.lastname: Wendehenne
authors.affiliation: Agroécologie, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, Dijon, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Jeandroz
authors.affiliation: Agroécologie, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, Dijon, France.
authors.forename: Hoai-Nam
authors.initials: HN
authors.lastname: Truong
mesh_terms: D044744:Aphanomyces / Q000472:pathogenicity*; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D046913:Medicago truncatula / Q000378:metabolism* / Q000382:microbiology*; D009566:Nitrates / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D009566:Nitrates; D010940:Plant Proteins; D009584:Nitrogen
keywords: Medicago truncatula; amino acids, Aphanomyces euteiches; glutamine; nitrate; nitrogen; plant defence