title: Glyoxylate cycle and metabolism of organic acids in the scutellum of barley seeds during germination.
abstract: During the developmental processes from dry seeds to seedling establishment, the glyoxylate cycle becomes active in the mobilization of stored oils in the scutellum of barley (Hordeum vulgare L.) seeds, as indicated by the activities of isocitrate lyase and malate synthase. The succinate produced is converted to carbohydrates via phosphoenolpyruvate carboxykinase and to amino acids via aminotransferases, while free organic acids may participate in acidifying the endosperm tissue, releasing stored starch into metabolism. The abundant organic acid in the scutellum was citrate, while malate concentration declined during the first three days of germination, and succinate concentration was low both in scutellum and endosperm. Malate was more abundant in endosperm tissue during the first three days of germination; before citrate became predominant, indicating that malate may be the main acid acidifying the endosperm. The operation of the glyoxylate cycle coincided with an increase in the ATP/ADP ratio, a buildup of H2O2 and changes in the redox state of ascorbate and glutathione. It is concluded that operation of the glyoxylate cycle in the scutellum of cereals may be important not only for conversion of fatty acids to carbohydrates, but also for the acidification of endosperm and amino acid synthesis.
authors.affiliation: Department of Biology, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada; Genomics and Biotechnology, London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON N5V 4T3, Canada; Department of Biology, University of Western Ontario, London, ON N6A 5B7, Canada.
authors.forename: Zhenguo
authors.initials: Z
authors.lastname: Ma
authors.affiliation: Genomics and Biotechnology, London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON N5V 4T3, Canada; Department of Biology, University of Western Ontario, London, ON N6A 5B7, Canada.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Marsolais
authors.affiliation: Department of Biology, University of Western Ontario, London, ON N6A 5B7, Canada.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Bernards
authors.affiliation: Genomics and Biotechnology, London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON N5V 4T3, Canada.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Sumarah
authors.affiliation: Morden Research and Development Centre, Agriculture and Agri-Food Canada, Morden, MB R6 M 1Y5, Canada.
authors.forename: Natalia V
authors.initials: NV
authors.lastname: Bykova
authors.affiliation: Department of Biology, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada. Electronic address: igamberdiev@mun.ca.
authors.forename: Abir U
authors.initials: AU
authors.lastname: Igamberdiev
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000410:Alanine Transaminase / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism; D001205:Ascorbic Acid / Q000378:metabolism; D056625:Endosperm / Q000378:metabolism; D005649:Fumarate Hydratase / Q000378:metabolism; D018525:Germination / Q000502:physiology*; D005978:Glutathione / Q000378:metabolism; D006038:Glyoxylates / Q000378:metabolism*; D001467:Hordeum / Q000254:growth & development* / Q000378:metabolism; D010730:Phosphoenolpyruvate Carboxylase / Q000378:metabolism; D012639:Seeds / Q000254:growth & development* / Q000378:metabolism; D013385:Succinate Dehydrogenase / Q000378:metabolism
chemical_list: D000596:Amino Acids; D006038:Glyoxylates; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D013385:Succinate Dehydrogenase; D000410:Alanine Transaminase; D010730:Phosphoenolpyruvate Carboxylase; D005649:Fumarate Hydratase; D005978:Glutathione; C031150:glyoxylic acid; D001205:Ascorbic Acid
keywords: Ascorbate; Barley (Hordeum vulgare L.); Citrate; Glutathione; Glyoxylate cycle; Malate; Seed germination; Succinate