Identification of organic acid-related genes and their expression profiles in two pear (Pyrus pyrifolia) cultivars with difference in predominant acid type at fruit ripening stage

► Citric acid predominant accumulation occurs in Pyrus Pyrifolia 'Yandangxueli'. ► Five acid-related genes were identified from pear (P. Pyrifolia) firstly. ► Storage-related genes are involved in high-citric acid accumulation. ► Enzymes' activities were not correlated with citric acid accumulation directly.