PLANT PHYSIOLOGY , Vol 110, Issue 2 465-470, Copyright © 1996 by American Society of Plant Biologists
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BIOCHEMISTRY AND ENZYMOLOGY |
Diauxic Growth in Rice Suspension Cells Grown on Mixed Carbon Sources of Acetate and Glucose
T. K. Lee and W. S. Lee
Department of Biology, Sung Kyun Kwan University, Suwon, Korea 440-746
Diauxic growth was observed in rice (Oryza sativa L.) suspension cells
growing on acetate (10 mM) and glucose (10 mM). Cells used acetate during
the first growth phase and the acetate level in the medium was rapidly
decreased, whereas the level of glucose remained essentially unchanged.
After acetate was depleted from the medium, cells started to use glucose,
forming the second growth phase. It appears that uptake of [14C]glucose was
repressed during the first growth phase and became active during the second
growth phase. In contrast, uptake of [14C]acetate occurred actively
throughout the diauxic growth. By further demonstrating the specific
induction of isocitrate lyase (EC 4.1.3.1), a glyoxylate cycle enzyme, and
hexokinase (EC 2.7.1.1), a glycolysis enzyme, during the first and second
growth phases, respectively, it was clearly shown that rice cells use
acetate first and do not use both carbon sources simultaneously. This kind
of diauxic growth pattern has been observed in bacteria. To our knowledege,
this study is the first report demonstrating the presence of diauxic growth
in plant cells.
