ISHS Acta Horticulturae 465: IV International Peach Symposium
ORGANIC ACID METABOLISM DURING THE FRUIT DEVELOPMENT OF TWO PEACH CULTIVARS |
| Authors: | A. Moing, L. Svanella, R. Monet, C. Rothan, D. Just, P. Diakou, J.P. Gaudillère, D. Rolin |
| Keywords: | Acidity, Citric acid, Énzyme activity, Malic acid, pH, Prunus persica |
| Abstract:
Two peach [Prunus persica (L.) Batsch] cultivars were studied for their organic acid content and metabolism in fruit mesocarp. Fantasia has fruits with normal acidity and pH, whereas Ferjalou-Jalousia® has fruits with low acidity and high pH (about 4.5 at maturity). The changes in organic acid contents were measured from 3 weeks after bloom to maturity, in fruits from greenhouse-cultivated trees. For both cvs, the two major organic acids were malic and citric acids. The Ferjalou-Jalousia® fruits did not accumulate malic and citric acids during their development. This difference could explain the difference observed in titratable acidity at maturity. To understand the metabolic origin of the difference in malic and citric acid content, we studied the enzymes involved in malate synthesis (phosphoenolpyruvate carboxylase and malate dehydrogenase) or degradation (malic enzyme). The differences observed between the two cultivars for phosphoenolpyruvate carboxylase, malate dehydrogenase and malic enzyme activities, measured in vitro under optimal conditions, could not be correlated with the difference in acid contents. The in vivo regulation of PEP carboxylase is discussed, as malate strongly inhibits PEP carboxylase activity. Therefore, the two cultivars may differ for their aptitude to store organic acids in the vacuole of mesocarp cells. | |
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