Changes in the organic acid content and related metabolic enzyme activities in developing Xinping pear fruit

Abstract

Changes in the content of citric acid and malic acid and the activities of enzymes involved in the metabolism of these two organic acids, including citrate synthase (CS), aconitase (ACO), isocitrate dehydrogenase (IDH),phosphoenolpyruvate carboxylase (PEPC), NAD-malate dehydrogenase (NAD-MDH) and NADP-malic enzyme (NADP-ME) were examined during the process of fruit development in ‘Xinping’ pear. The citric and malic acid content exhibited an overall increasing trend in developing fruit. The activities of CS, NAD-IDH and NAD-MDH showed an overall increasing trend and the activities of Cyt-ACO, PEPC and NADP-ME exhibited an overall decreasing trend in developing fruit. The correlation analysis of the change in the organic acid content and related metabolic enzyme activities during the development of the fruit revealed that CS, ACO, IDH, PEPC, NAD-MDH and NADP-ME are considered important enzymes that affect the synthesis of citric acid and malic acid in pear fruits. Key words: Pear, fruit, development, organic acid, metabolic enzyme, correlation.