Changes in the organic acid content and related metabolic enzyme activities in developing ‘Dangshansuli’ 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 ‘Dangshansuli’ pear. The citric exhibited an
overall decreasing trend and the malic acid content exhibited an overall increasing trend in developing fruit. The
activities of CS, NAD-IDH, NAD-MDH and NADP-ME showed an overall increasing trend and the activities of CytACO and PEPC 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