title: RNA-seq transcriptome profiling reveals that Medicago truncatula nodules acclimate N₂ fixation before emerging P deficiency reaches the nodules.
abstract: Legume nodules are plant tissues with an exceptionally high concentration of phosphorus (P), which, when there is scarcity of P, is preferentially maintained there rather than being allocated to other plant organs. The hypothesis of this study was that nodules are affected before the P concentration in the organ declines during whole-plant P depletion. Nitrogen (N₂) fixation and P concentration in various organs were monitored during a whole-plant P-depletion process in Medicago truncatula. Nodule gene expression was profiled through RNA-seq at day 5 of P depletion. Until that point in time P concentration in leaves reached a lower threshold but was maintained in nodules. N₂-fixation activity per plant diverged from that of fully nourished plants beginning at day 5 of the P-depletion process, primarily because fewer nodules were being formed, while the activity of the existing nodules was maintained for as long as two weeks into P depletion. RNA-seq revealed nodule acclimation on a molecular level with a total of 1140 differentially expressed genes. Numerous genes for P remobilization from organic structures were increasingly expressed. Various genes involved in nodule malate formation were upregulated, while genes involved in fermentation were downregulated. The fact that nodule formation was strongly repressed with the onset of P deficiency is reflected in the differential expression of various genes involved in nodulation. It is concluded that plants follow a strategy to maintain N₂ fixation and viable leaf tissue as long as possible during whole-plant P depletion to maintain their ability to react to emerging new P sources (e.g. through active P acquisition by roots).
authors.affiliation: Department of Crop Science, Section for Plant Nutrition and Crop Physiology, Faculty of Agriculture, University of Goettingen, Carl-Sprengel-Weg 1, 37075 Goettingen, Germany.
authors.forename: Ricardo A
authors.initials: RA
authors.lastname: Cabeza
authors.affiliation: Department of Crop Science, Section for Plant Nutrition and Crop Physiology, Faculty of Agriculture, University of Goettingen, Carl-Sprengel-Weg 1, 37075 Goettingen, Germany.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Liese
authors.affiliation: Department of Crop Science, Section for Plant Nutrition and Crop Physiology, Faculty of Agriculture, University of Goettingen, Carl-Sprengel-Weg 1, 37075 Goettingen, Germany.
authors.forename: Annika
authors.initials: A
authors.lastname: Lingner
authors.affiliation: Department of Crop Science, Section for Plant Nutrition and Crop Physiology, Faculty of Agriculture, University of Goettingen, Carl-Sprengel-Weg 1, 37075 Goettingen, Germany.
authors.forename: Ilsabe
authors.initials: I
authors.lastname: von Stieglitz
authors.affiliation: Department of Crop Science, Section for Plant Nutrition and Crop Physiology, Faculty of Agriculture, University of Goettingen, Carl-Sprengel-Weg 1, 37075 Goettingen, Germany.
authors.forename: Janice
authors.initials: J
authors.lastname: Neumann
authors.affiliation: Department of Developmental Biochemistry, DNA Microarray and Deep-Sequencing Facility, Faculty of Medicine, University of Goettingen, Justus-von-Liebig-Weg 11, 37077 Goettingen, Germany.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Salinas-Riester
authors.affiliation: Department of Developmental Biochemistry, DNA Microarray and Deep-Sequencing Facility, Faculty of Medicine, University of Goettingen, Justus-von-Liebig-Weg 11, 37077 Goettingen, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Pommerenke
authors.affiliation: Department of Crop Science, Section for Plant Nutrition and Crop Physiology, Faculty of Agriculture, University of Goettingen, Carl-Sprengel-Weg 1, 37075 Goettingen, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Dittert
authors.affiliation: Department of Crop Science, Section for Plant Nutrition and Crop Physiology, Faculty of Agriculture, University of Goettingen, Carl-Sprengel-Weg 1, 37075 Goettingen, Germany jschulz2@gwdg.de.
authors.forename: Joachim
authors.initials: J
authors.lastname: Schulze
mesh_terms: D000064:Acclimatization; D018506:Gene Expression Regulation, Plant; D046913:Medicago truncatula / Q000235:genetics* / Q000382:microbiology / Q000502:physiology; D009584:Nitrogen / Q000378:metabolism; D009586:Nitrogen Fixation; D010641:Phenotype; D010758:Phosphorus / Q000172:deficiency* / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000382:microbiology / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics; D055170:Plant Root Nodulation; D018517:Plant Roots / Q000235:genetics / Q000382:microbiology / Q000502:physiology; D053204:Root Nodules, Plant / Q000235:genetics / Q000382:microbiology / Q000502:physiology; D017423:Sequence Analysis, RNA; D016962:Sinorhizobium meliloti / Q000502:physiology*; D013559:Symbiosis; D059467:Transcriptome
chemical_list: D010940:Plant Proteins; D010758:Phosphorus; D009584:Nitrogen
keywords: Legumes; Medicago truncatula; N2 fixation; P stress; RNA-seq; Sinorhizobium meliloti.; nitrogen fixation; nodulation