title: Do initial S reserves and mineral S availability alter leaf S-N mobilization and leaf senescence in oilseed rape?
abstract: Winter oilseed rape is sensitive to S limitation, however few studies have clearly assessed the impact of initial S reserves on the remobilization of leaf N-S compounds and senescence dynamics within the leaves in S limited plants. As a consequence, the impacts of high or low initial S reserves on these parameters, further cross-combined with either high or low S availabilities, were examined using a ¹⁵N and ³⁴S double-labelling method associated with a study of gene expression of relevant tonoplastic sulphate transporters (BnSultr4;1 and BnSultr4;2) and a molecular indicator of leaf senescence (BnSAG12/BnCab). Plants with high initial S status and S limitation showed an optimal growth comparable to control plants. Moreover, in response to S limitation, leaf soluble protein content, total S, recently assimilated S (i.e., ³⁴S) and the sulphate content in the oldest leaves declined, and the expression of genes encoding tonoplastic sulphate transporters were up-regulated. However, compared to control plants, S limitation delayed leaf senescence. These data suggested that in response to S limitation, plants with high initial S were able to sustain optimized leaf growth by increasing endogenous N and S remobilization independently of the leaf senescence process. In contrast, if these low S plants had no initial S reserves, leaf N-S remobilization was not sufficient to allow optimal growth. As a conclusion, our study supports a model where oilseed rape is able to compensate transiently for S limitation through a fine management of leaf N-S remobilization and a delayed leaf senescence dynamics.
authors.affiliation: UMR INRA-UCBN 950, Ecophysiologie Végétale, Agronomie and Nutritions N. C. S. (EVA), INRA, University Caen, F-14032 Caen, France.
authors.forename: M
authors.initials: M
authors.lastname: Abdallah
authors.forename: P
authors.initials: P
authors.lastname: Etienne
authors.forename: A
authors.initials: A
authors.lastname: Ourry
authors.forename: F
authors.initials: F
authors.lastname: Meuriot
mesh_terms: D027321:Anion Transport Proteins / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport; D029741:Brassica rapa / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D016922:Cellular Senescence; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D045342:Light-Harvesting Protein Complexes / Q000235:genetics / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes; D045332:Photosystem II Protein Complex / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012995:Solubility; D013194:Staining and Labeling; D013431:Sulfates / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism*; D013460:Sulfur Isotopes; D015854:Up-Regulation
chemical_list: D027321:Anion Transport Proteins; D045342:Light-Harvesting Protein Complexes; D009587:Nitrogen Isotopes; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D013431:Sulfates; D013460:Sulfur Isotopes; D013455:Sulfur; D003546:Cysteine Endopeptidases; D009584:Nitrogen