Abstract:The low ratio of sugars and organic acids is one of the major reasons for poor taste in kernelapricot sarcocarp. In this study, to understand the expression patterns of genes which may be associated with sugar and organic acids synthesis and to indentify the molecular regulation pattern and mechanism of the low ratio of sugars and organic acids, we used RNAseq technique to obtain the transcriptomes and expression profiles of three developing stages (30, 60 and 90 days after flowering) about kernelapricot sarcocarp of ‘Shanku 2 hao’ to provide a basis for the study of the metabolic and conversion mechanism of sugars and organic acids in kernelapricot sarcocarp.The results showed that: (1) 28 989 differently expressed unigenes were obtained during the three developing stages.According to the unigene annotation, 5 enzymes encoded by 19 unigenes related to sugar biosynthesis and metabolism and 15 enzymes encoded by 54 unigenes involved in organic acids biosynthesis and metabolism were obtained; (2) Among the differently expressed unigenes, 9 and 27 unigenes of them which related to sugar and organic acid biosynthesis and metabolism were differently expressed in the three developing stages,respectively; (3) Most of the unigenes encoding the sucrosephosphate synthase and sucrose synthase which related to the sugar accumulation were downregulated, but the fructokinase and hexokinase that involved in sugar catabolism were upregulated; (4) The unigenes encoding malate dehydrogenase which associated with accumulation of malic acid was the main components of organic acids in kernelapricot sarcocarp were mainly upregulated. However, the malic enzyme catalyzed the breakdown of malic acid was downregulated. It can be sure that the accumulation of sugars was restrained, but the organic acids were synthesized and accumulated in large quantities during the developments of kernelapricot sarcocarp. This may be one of the main internal factors that contribute to the low ratio of sugars and organic acids and the poor taste of kernelapricot sarcocarp.