title: Nitrogen recycling and remobilization are differentially controlled by leaf senescence and development stage in Arabidopsis under low nitrogen nutrition.
abstract: Five recombinant inbred lines (RILs) of Arabidopsis (Arabidopsis thaliana), previously selected from the Bay-0 x Shahdara RIL population on the basis of differential leaf senescence phenotypes (from early senescing to late senescing) when cultivated under nitrogen (N)-limiting conditions, were analyzed to monitor metabolic markers related to N assimilation and N remobilization pathways. In each RIL, a decrease of total N, free amino acid, and soluble protein contents with leaf aging was observed. In parallel, the expression of markers for N remobilization such as cytosolic glutamine synthetase, glutamate dehydrogenase, and CND41-like protease was increased. This increase occurred earlier and more rapidly in early-senescing lines than in late-senescing lines. We measured the partitioning of (15)N between sink and source leaves during the vegetative stage of development using (15)N tracing and showed that N remobilization from the source leaves to the sink leaves was more efficient in the early-senescing lines. The N remobilization rate was correlated with leaf senescence severity at the vegetative stage. Experiments of (15)N tracing at the reproductive stage showed, however, that the rate of N remobilization from the rosettes to the flowering organs and to the seeds was similar in early- and late-senescing lines. At the reproductive stage, N remobilization efficiency did not depend on senescence phenotypes but was related to the ratio between the biomasses of the sink and the source organs.
authors.affiliation: Unité de Nutrition Azotée des Plantes, UR511, INRA, F-78000 Versailles, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Diaz
authors.forename: Thomas
authors.initials: T
authors.lastname: Lemaître
authors.forename: Aurélie
authors.initials: A
authors.lastname: Christ
authors.forename: Marianne
authors.initials: M
authors.lastname: Azzopardi
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kato
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Sato
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Morot-Gaudry
authors.forename: Frédérik
authors.initials: F
authors.lastname: Le Dily
authors.forename: Céline
authors.initials: C
authors.lastname: Masclaux-Daubresse
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D018533:Biomass; D002244:Carbon / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes / Q000378:metabolism; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D013213:Starch / Q000378:metabolism; D013997:Time Factors
chemical_list: D000596:Amino Acids; D029681:Arabidopsis Proteins; D009587:Nitrogen Isotopes; D012333:RNA, Messenger; D002734:Chlorophyll; D002244:Carbon; D013213:Starch; D012273:Ribulose-Bisphosphate Carboxylase; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen