Changes in Hexokinase Activity in<i>Echinochloa phyllopogon</i> and <i>Echinochloa crus-pavonis</i> in Response to Abiotic Stress

DOI PDF 2 Citations
  • Theodore C. Fox
    Program in Plant Physiology and Plant Biotechnology and Departments of Horticultural Sciences (T.C.F., B.J.G., M.E.R.),
  • Brian J. Green
    Program in Plant Physiology and Plant Biotechnology and Departments of Horticultural Sciences (T.C.F., B.J.G., M.E.R.),
  • Robert A. Kennedy
    and Biology (R.A.K.), Texas A&M University, College Station, Texas 77843
  • Mary E. Rumpho
    Program in Plant Physiology and Plant Biotechnology and Departments of Horticultural Sciences (T.C.F., B.J.G., M.E.R.),

Abstract

<jats:title>Abstract</jats:title> <jats:p>Hexokinase (HXK; EC 2.7.1.1) regulates carbohydrate entry into glycolysis and is known to be a sensor for sugar-responsive gene expression. The effect of abiotic stresses on HXK activity was determined in seedlings of the flood-tolerant plant Echinochloa phyllopogon (Stev.) Koss and the flood-intolerant plant Echinochloa crus-pavonis (H.B.K.) Schult grown aerobically for 5 d before being subjected to anaerobic, chilling, heat, or salt stress. HXK activity was stimulated in shoots of E. phyllopogononly by anaerobic stress. HXK activity was only transiently elevated inE. crus-pavonis shoots during anaerobiosis. In roots of both species, anoxia and chilling stimulated HXK activity. Thus, HXK is not a general stress protein but is specifically induced by anoxia and chilling in E. phyllopogon and E. crus-pavonis. In both species HXK exhibited an optimum pH between 8.5 and 9.0, but the range was extended to pH 7.0 in air-grownE. phyllopogon to 6.5 in N2-grown E. phyllopogon. At physiologically relevant pHs (6.8 and 7.3, N2 and O2 conditions, respectively), N2-grown seedlings retained greater HXK activity at the lower pH. The pH response suggests that in N2-grown seedlings HXK can function in a more acidic environment and that a specific isozyme may be important for regulating glycolytic activity during anaerobic metabolism in E. phyllopogon.</jats:p>

Journal

  • Plant Physiology

    Plant Physiology 118 (4), 1403-1409, 1998-12-01

    Oxford University Press (OUP)

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