Mitochondrial biogenesis during germination in maize embryos

David Logan, AH Millar, LJ Sweetlove, SA Hill, CJ Leaver

Research output: Contribution to journalArticlepeer-review

117 Citations (Scopus)

Abstract

Mitochondrial biogenesis and metabolism were investigated during maize (Zea mays) seed germination. Mitochondria from dry and imbibed seed exhibited NADH-dependent O-2 uptake that was completely inhibited by KCN and antimycin A. Mitochondria in the dry seed had a lower rate of succinate-dependent O-2 uptake relative to that measured in imbibed and germinated seed. The activities of the tricarboxylic acid (TCA) cycle enzymes, pyruvate dehydrogenase complex, 2-oxoglutarate dehydrogenase complex, NAD-malic enzyme, and citrate synthase, are similarly low in mitochondria from dry seed and this correlates with a lower relative abundance of the mitochondrial matrix-located citrate synthase and pyruvate dehydrogenase complex E1 alpha -subunit polypeptides. Electron microscopy revealed that mitochondria in the dry seed have a poorly developed internal membrane structure with few cristae; following 24 h of germination the mitochondria developed a more normal structure with more developed cristae. The mitochondria from maize embryos could be fractionated into two subpopulations by Suc density gradient centrifugation: one subpopulation of buoyant density equivalent to 22% to 28% (w/w) Sue; the other equivalent to 37% to 42% (w/w) Sue. These two subpopulations had different activities of specific mitochondrial enzymes and contained different amounts of specific mitochondrial proteins as revealed by western-blot analysis. Both subpopulations from the dry embryo were comprised of poorly developed mitochondria. However, during imbibition mitochondria in the heavy fraction (37%-42% [w/w] Sue) progressively acquired characteristics of fully functional mitochondria found in the germinated seedling in terms of structure, enzymic activity, and protein complement. In contrast, mitochondria in the light fraction (22% to 28% [w/w] Sue) show no significant structural change during imbibition and the amounts of specific mitochondrial proteins decreased significantly during germination.

Original languageEnglish
Pages (from-to)662-672
Number of pages11
JournalPlant Physiology
Volume125
Issue number2
DOIs
Publication statusPublished - Feb 2001

Keywords

  • MONOCLONAL-ANTIBODIES
  • DEHYDROGENASE
  • RESPIRATION
  • PROTEIN
  • PHOSPHORYLATION
  • COTYLEDONS
  • SUBUNIT
  • SEEDS
  • GENE

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