PLANT PHYSIOLOGY , Vol 109, Issue 2 433-443, Copyright © 1995 by American Society of Plant Biologists
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WHOLE PLANT, ENVIRONMENTAL, AND STRESS PHYSIOLOGY |
Identification and Gene Expression of Anaerobically Induced Enolase in Echinochloa phyllopogon and Echinochloa crus-pavonis
T. C. Fox, C. V. Mujer, D. L. Andrews, A. S. Williams, B. G. Cobb, R. A. Kennedy and M. E. Rumpho
Department of Horticultural Sciences (T.C.F., C.V.M., D.L.A., A.S.W., B.G.C., M.E.R.), and Department of Biology (R.A.K.), Texas A&M University, College Station, Texas 77843
Enolase (2-phospho-D-glycerate hydrolase, EC 4.2.1.11) has been identified
as an anaerobic stress protein in Echinochloa oryzoides based on the
homology of its internal amino acid sequence with those of enolases from
other organisms, by immunological reactivity, and induction of catalytic
activity during anaerobic stress. Enolase activity was induced 5-fold in
anoxically treated seedlings of three flood-tolerant species (E. oryzoides,
Echinochloa phyllopogon, and rice [Oryza sativa L.]) but not in the
flood-intolerant species (Echinochloa crus-pavonis). A 540-bp fragment of
the enolase gene was amplified by polymerase chain reaction from cDNAs of
E. phyllopogon and maize (Zea mays L.) and used to estimate the number of
enolase genes and to study the expression of enolase transcripts in E.
phyllopogon, E. crus-pavonis, and maize. Southern blot analysis indicated
that only one enolase gene is present in either E. phyllopogon or E.
crus-pavonis. Three patterns of enolase gene expression were observed in
the three species studied. In E. phyllopogon, enolase induction at both the
mRNA and enzyme activity levels was sustained at all times with a further
induction after 48 h of anoxia. In contrast, enolase was induced in
hypoxically treated maize root tips only at the mRNA level. In E.
crus-pavonis, enolase mRNA and enzyme activity were induced during hypoxia,
but activity was only transiently elevated. These results suggest that
enolase expression in maize and E. crus-pavonis during anoxia are similarly
regulated at the transcriptional level but differ in post-translational
regulation, whereas enolase is fully induced in E. phyllopogon during
anaerobiosis.
