title: Transcriptomic analysis of nitrogen starvation- and cultivar-specific leaf senescence in winter oilseed rape (Brassica napus L.).
abstract: High nitrogen (N) efficiency, characterized by high grain yield under N limitation, is an important agricultural trait in Brassica napus L. cultivars related to delayed senescence of older leaves during reproductive growth (a syndrome called stay-green). The aim of this study was thus to identify genes whose expression is specifically altered during N starvation-induced leaf senescence and that can be used as markers to distinguish cultivars at early stages of senescence prior to chlorophyll loss. To this end, the transcriptomes of leaves of two B. napus cultivars differing in stay-green characteristics and N efficiency were analyzed 4 days after the induction of senescence by either N starvation, leaf shading or detaching. In addition to N metabolism genes, N starvation mostly (and specifically) repressed genes related to photosynthesis, photorespiration and cell-wall structure, while genes related to mitochondrial electron transport and flavonoid biosynthesis were predominately up-regulated. A kinetic study over a period of 12 days with four B. napus cultivars differing in their stay-green characteristics confirmed the cultivar-specific regulation of six genes in agreement with their senescence behavior: the senescence regulator ANAC029, the anthocyanin synthesis-related genes ANS and DFR-like1, the ammonium transporter AMT1;4, the ureide transporter UPS5, and SPS1 involved in sucrose biosynthesis. The identified genes represent markers for the detection of cultivar-specific differences in N starvation-induced leaf senescence and can thus be employed as valuable tools in B. napus breeding.
authors.affiliation: Institute of Plant Nutrition, Leibniz University of Hannover, Herrenhäuser Str. 2, D-30419 Hannover, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Koeslin-Findeklee
authors.affiliation: Institute of Biology, Dahlem Centre of Plant Sciences, Free University Berlin, Albrecht-Thaer-Weg 6, D-14195 Berlin, Germany.
authors.forename: Vajiheh Safavi
authors.initials: VS
authors.lastname: Rizi
authors.affiliation: Institute of Plant Nutrition, Leibniz University of Hannover, Herrenhäuser Str. 2, D-30419 Hannover, Germany.
authors.forename: Martin A
authors.initials: MA
authors.lastname: Becker
authors.affiliation: Institute of Plant Nutrition, Leibniz University of Hannover, Herrenhäuser Str. 2, D-30419 Hannover, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Parra-Londono
authors.affiliation: Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam, Germany; Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Arif
authors.affiliation: Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam, Germany; Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany.
authors.forename: Salma
authors.initials: S
authors.lastname: Balazadeh
authors.affiliation: Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam, Germany; Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Mueller-Roeber
authors.affiliation: Institute of Biology, Dahlem Centre of Plant Sciences, Free University Berlin, Albrecht-Thaer-Weg 6, D-14195 Berlin, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Kunze
authors.affiliation: Institute of Plant Nutrition, Leibniz University of Hannover, Herrenhäuser Str. 2, D-30419 Hannover, Germany. Electronic address: horst@pflern.uni-hannover.de.
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Horst
mesh_terms: D029688:Brassica napus / Q000235:genetics* / Q000254:growth & development; D002734:Chlorophyll / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism*; D010788:Photosynthesis; D018515:Plant Leaves / Q000254:growth & development; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D059467:Transcriptome
chemical_list: D010940:Plant Proteins; D002734:Chlorophyll; D009584:Nitrogen
keywords: Brassica napus; Genotypic differences; Leaf senescence; Molecular marker; N efficiency; Stay-green