title: Transcriptome analysis of the Populus trichocarpa-Rhizophagus irregularis Mycorrhizal Symbiosis: Regulation of Plant and Fungal Transportomes under Nitrogen Starvation.
abstract: Nutrient transfer is a key feature of the arbuscular mycorrhizal (AM) symbiosis. Valuable mineral nutrients are transferred from the AM fungus to the plant, increasing its fitness and productivity, and, in exchange, the AM fungus receives carbohydrates as an energy source from the plant. Here, we analyzed the transcriptome of the Populus trichocarpa-Rhizophagus irregularis symbiosis using RNA-sequencing of non-mycorrhizal or mycorrhizal fine roots, with a focus on the effect of nitrogen (N) starvation. In R. irregularis, we identified 1,015 differentially expressed genes, whereby N starvation led to a general induction of gene expression. Genes of the functional classes of cell growth, membrane biogenesis and cell structural components were highly abundant. Interestingly, N starvation also led to a general induction of fungal transporters, indicating increased nutrient demand upon N starvation. In non-mycorrhizal P. trichocarpa roots, 1,341 genes were differentially expressed under N starvation. Among the 953 down-regulated genes in N starvation, most were involved in metabolic processes including amino acids, carbohydrate and inorganic ion transport, while the 342 up-regulated genes included many defense-related genes. Mycorrhization led to the up-regulation of 549 genes mainly involved in secondary metabolite biosynthesis and transport; only 24 genes were down-regulated. Mycorrhization specifically induced expression of three ammonium transporters and one phosphate transporter, independently of the N conditions, corroborating the hypothesis that these transporters are important for symbiotic nutrient exchange. In conclusion, our data establish a framework of gene expression in the two symbiotic partners under high-N and low-N conditions.
authors.affiliation: Department of Environmental Sciences, Botany, Zurich-Basel Plant Science Center, University of Basel, Hebelstrasse, Basel, Switzerland.
authors.forename: Silvia
authors.initials: S
authors.lastname: Calabrese
authors.affiliation: INRA, UMR1136 Interactions Arbres-Microorganismes, Champenoux, France.|Université de Lorraine, UMR1136 Interactions Arbres-Microorganismes, Vandoeuvre-lès-Nancy, France.
authors.forename: Annegret
authors.initials: A
authors.lastname: Kohler
authors.affiliation: Department of Environmental Sciences, Botany, Zurich-Basel Plant Science Center, University of Basel, Hebelstrasse, Basel, Switzerland.
authors.forename: Annette
authors.initials: A
authors.lastname: Niehl
authors.affiliation: INRA, UMR1136 Interactions Arbres-Microorganismes, Champenoux, France.|Université de Lorraine, UMR1136 Interactions Arbres-Microorganismes, Vandoeuvre-lès-Nancy, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Veneault-Fourrey
authors.affiliation: Department of Environmental Sciences, Botany, Zurich-Basel Plant Science Center, University of Basel, Hebelstrasse, Basel, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Boller
authors.affiliation: Department of Environmental Sciences, Botany, Zurich-Basel Plant Science Center, University of Basel, Hebelstrasse, Basel, Switzerland.|Agroécologie, AgroSupDijon, CNRS, INRA, Université de Bourgogne Franche-Comté, Dijon, France.
authors.forename: Pierre-Emmanuel
authors.initials: PE
authors.lastname: Courty
mesh_terms: D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D038821:Mycorrhizae / Q000502:physiology*; D009584:Nitrogen / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D032107:Populus / Q000235:genetics* / Q000382:microbiology*; D013559:Symbiosis / Q000235:genetics / Q000502:physiology
chemical_list: D010940:Plant Proteins; D009584:Nitrogen
keywords: Ammonium transporter; Arbuscular mycorrhiza; Nitrogen metabolism; Populus trichocarpa; Rhizophagus irregularis; Symbiosis; Transcriptome; Transportome