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ISSN
1672-9145
Acta Biochim Biophys Sin
2005, 37(6): 406–414
CN 31-1940/Q
Anaerobic Induction of Isocitrate Lyase and Malate Synthase in
Submerged Rice Seedlings Indicates the Important Metabolic Role of the
Glyoxylate Cycle
Ying LU1,2#, Yong-Rui WU1,2#, and Bin HAN1,3*
1 National Center for Gene Research, Shanghai Institutes for
Biological Sciences, Chinese Academy of Sciences, Shanghai 200233, China;
2 Graduate School of the Chinese Academy of Sciences, Beijing 100039,
China;
3 Institute of Plant Physiology and Ecology, Shanghai Institutes for
Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
Abstract The glyoxylate cycle is
a modified form of the tricarboxylic acid cycle that converts C2 compounds into
C4 dicarboxylic acids at plant developmental stages. By studying submerged rice
seedlings, we revealed the activation of the glyoxylate cycle by identifying
the increased transcripts of mRNAs of the genes of isocitrate lyase (ICL) and
malate synthase (MS), two characteristic enzymes of the glyoxylate cycle.
Northern blot analysis showed that ICL and MS were activated in the prolonged
anaerobic environment. The activity assay of pyruvate decarboxylase and ICL in
the submerged seedlings indicated an 8.8-fold and 3.5-fold increase over that
in the unsubmerged seedlings, respectively. The activity assay of
acetyl-coenzyme A synthetase in the submerged seedlings indicated a 3-fold increase over that in the
unsubmerged seedlings, which is important for initiating acetate metabolism.
Consequently, we concluded that the glyoxylate cycle was involved in acetate
metabolism under anaerobic conditions.
Key words Oryza sativa;
glyoxylate cycle; isocitrate lyase; malate synthase; acetyl-coenzyme A
synthetase; anoxia
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Received: March 23, 2005 Accepted: April 14, 2005
This work was supported by the grants from the Ministry of Science
and Technology of China (No. 2002aa2z1003), the Chinese Academy of Sciences and
the Shanghai Municipal Commission of Sciences and Technology (No. 038019315)
# These authors contributed equally to
this work
*Corresponding author: Tel: 86-21-64845260; Fax, 86-21-64825775;
E-mail, [email protected]