Effect of metabolic enzyme on organic acids in developing ‘Dangshansuli’ pear leaf
Changes in the content of citric and malic acids and the activities of enzymes involved in the metabolism of these two organic acids, including citrate synthase (CS), cytoplast aconitase (Cyt-ACO), NAD-isocitrate dehydrogenase (NAD-IDH), phosphoenolpyruvate carboxylase (PEPC), NAD-malate dehydrogenase (NAD-MDH) and NADP-malic enzyme (NADP-ME), were examined during the process of leaf development in ‘Dangshansuli’ pear. The citric acid content exhibited an overall slightly decreasing trend and the malic acid content exhibited an overall appreciably increasing trend in developing leaf. The activities of CS, Cyt-ACO, NAD-IDH, PEPC and NAD-MDH all showed an overall decreasing trend, whereas the activities of NADP-ME indicated an overall increasing trend. The correlation analysis of the change in the organic acid content and related metabolic enzyme activities during the development of the leaf revealed that the activities of CS, Cyt-ACO and NAD-IDH showed a negative correlation with the content of citrc acid, the activities of PEPC exhibited a positive correlation with the content of malic acid, the activities of NAD-MDH and NADP-ME indicated a negative correlation with the content of malic acid.
Key words: Pear, leaf, development, organic acid, metabolic enzyme, correlation.