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Journal of Plant Physiology
Or, E., Institute of Horticulture, Agricultural Res. Organization, Volcani Center, P.O.B. 6, Bet Dagan 50-250, Israel
Baybik, J., Institute of Horticulture, Agricultural Res. Organization, Volcani Center, P.O.B. 6, Bet Dagan 50-250, Israel
Sadka, A., Institute of Horticulture, Agricultural Res. Organization, Volcani Center, P.O.B. 6, Bet Dagan 50-250, Israel
Saks, Y., Institute of Horticulture, Agricultural Res. Organization, Volcani Center, P.O.B. 6, Bet Dagan 50-250, Israel
Malate accumulation in the grape berry, which takes place until the onset of ripening (veraison), is thought to occur mainly due to the combined activities of phosphoenolpyruvate carboxylase (PEPC) and malate dehydrogenase (MDH), which convert phosphoenolpyruvate to malate, via oxaloacetate. The rapid decrease in malate content during ripening has usually been attributed to its degradation by malic enzyme (ME) but it has also been related to MDH reverse reaction. Enzymological studies suggest that malate metabolism throughout berry development is controlled, at least partially, by the regulation of the level and/or activity of these enzymes. However, the mechanism by which the enzyme level is controlled is not clear. In an attempt to find out whether the developmental control of enzyme activity involves regulation of gene expression, we isolated PEPC, MDH and ME cDNA clones from grape berries and followed their expression pattern throughout berry development. PEPC transcript was detected only during the early stages of berry development, while acid accumulated, whereas both MDH and ME transcript levels peaked in the young berry, declined towards the onset of ripening and were induced again during ripening when there was a major reduction in acidity. The developmental changes in the mRNA levels of the three genes correlated well with the changes in enzyme activity reported previously. These findings may suggest that the control of malate metabolism throughout berry growth involves developmental regulation of PEPC, MDH and ME transcript availability.
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Isolation of mitochondrial malate dehydrogenase and phosphoenolpyruvate carboxylase cDNA clones from grape berries and analysis of their expression pattern throughout berry development
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Or, E., Institute of Horticulture, Agricultural Res. Organization, Volcani Center, P.O.B. 6, Bet Dagan 50-250, Israel
Baybik, J., Institute of Horticulture, Agricultural Res. Organization, Volcani Center, P.O.B. 6, Bet Dagan 50-250, Israel
Sadka, A., Institute of Horticulture, Agricultural Res. Organization, Volcani Center, P.O.B. 6, Bet Dagan 50-250, Israel
Saks, Y., Institute of Horticulture, Agricultural Res. Organization, Volcani Center, P.O.B. 6, Bet Dagan 50-250, Israel
Isolation of mitochondrial malate dehydrogenase and phosphoenolpyruvate carboxylase cDNA clones from grape berries and analysis of their expression pattern throughout berry development
Malate accumulation in the grape berry, which takes place until the onset of ripening (veraison), is thought to occur mainly due to the combined activities of phosphoenolpyruvate carboxylase (PEPC) and malate dehydrogenase (MDH), which convert phosphoenolpyruvate to malate, via oxaloacetate. The rapid decrease in malate content during ripening has usually been attributed to its degradation by malic enzyme (ME) but it has also been related to MDH reverse reaction. Enzymological studies suggest that malate metabolism throughout berry development is controlled, at least partially, by the regulation of the level and/or activity of these enzymes. However, the mechanism by which the enzyme level is controlled is not clear. In an attempt to find out whether the developmental control of enzyme activity involves regulation of gene expression, we isolated PEPC, MDH and ME cDNA clones from grape berries and followed their expression pattern throughout berry development. PEPC transcript was detected only during the early stages of berry development, while acid accumulated, whereas both MDH and ME transcript levels peaked in the young berry, declined towards the onset of ripening and were induced again during ripening when there was a major reduction in acidity. The developmental changes in the mRNA levels of the three genes correlated well with the changes in enzyme activity reported previously. These findings may suggest that the control of malate metabolism throughout berry growth involves developmental regulation of PEPC, MDH and ME transcript availability.
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