title: Metabolic and transcriptional transitions in barley glumes reveal a role as transitory resource buffers during endosperm filling.
abstract: During grain filling in barley (Hordeum vulgare L. cv. Barke) reserves are remobilized from vegetative organs. Glumes represent the vegetative tissues closest to grains, senesce late, and are involved in the conversion of assimilates. To analyse glume development and metabolism related to grain filling, parallel transcript and metabolite profiling in glumes and endosperm were performed, showing that glume metabolism and development adjusts to changing grain demands, reflected by specific signatures of metabolite and transcript abundances. Before high endosperm sink strength is established by storage product accumulation, glumes form early, intermediary sink organs, shifting then to remobilizing and exporting source organs. Metabolic and transcriptional transitions occur at two phases: first, at the onset of endosperm filling, as a consequence of endosperm sink activity and assimilate depletion in endosperm and vascular tissues; second, at late grain filling, by developmental ageing and senescence. Regulation of and transition between phases are probably governed by specific NAC and WRKY transcription factors, and both abscisic and jasmonic acid, and are accompanied by changed expression of specific nitrogen transporters. Expression and metabolite profiling suggest glume-specific mechanisms of assimilate conversion and translocation. In summary, grain filling and endosperm sink strength coordinate phase changes in glumes via metabolic, hormonal, and transcriptional control. This study provides a comprehensive view of barley glume development and metabolism, and identifies candidate genes and associated pathways, potentially important for breeding improved grain traits.
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany kohl@ipk-gatersleben.de.
authors.forename: Stefan
authors.initials: S
authors.lastname: Kohl
authors.affiliation: Christian-Albrechts-Universität zu Kiel, 24118 Kiel, Germany.
authors.forename: Julien
authors.initials: J
authors.lastname: Hollmann
authors.affiliation: Max-Planck-Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Erban
authors.affiliation: Max-Planck-Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Kopka
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Riewe
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany.
authors.forename: Winfriede
authors.initials: W
authors.lastname: Weschke
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany.
authors.forename: Hans
authors.initials: H
authors.lastname: Weber
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D056625:Endosperm / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D001467:Hordeum / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D010940:Plant Proteins; D014157:Transcription Factors; D000040:Abscisic Acid
keywords: ABA; N transport; NAC transcription factors; WRKY transcription factors.; barley (Hordeum vulgare L. cv. Barke); glumes; jasmonic acid; nitrogen (N) remobilization; seed development