Anaerobic induction of isocitrate lyase and malate synthase in submerged rice seedlings indicates the important metabolic role of the glyoxylate cycle.
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.
Lu
Ying
Y
National Center for Gene Research, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200233, China.
Wu
Yong-Rui
YR
Han
Bin
B
D000106:Acetate-CoA Ligase / Q000096:biosynthesis; D000595:Amino Acid Sequence; D000693:Anaerobiosis / Q000502:physiology*; D002952:Citric Acid Cycle / Q000502:physiology*; D003001:Cloning, Molecular; D004790:Enzyme Induction; D006038:Glyoxylates / Q000378:metabolism*; D007522:Isocitrate Lyase / Q000096:biosynthesis*; D008292:Malate Synthase / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D012275:Oryza / Q000201:enzymology*; D036226:Seedlings / Q000201:enzymology*; D016415:Sequence Alignment
D006038:Glyoxylates; D008292:Malate Synthase; D007522:Isocitrate Lyase; D000106:Acetate-CoA Ligase; C031150:glyoxylic acid