Abstract:Passion fruit has a strong flavor.However，there can be sharp distinctions between the sweet tastes of different cultivars.The main factor determining a cultivar's sweetness and flavor is its sugar content.To characterize relationships between sugar content and expression of sugar metabolism-related genes in three varieties of passion fruit，a qualitative and quantitative analysis of sugar content has been carried out by gas chromatography-mass spectrometry （GC-MS）.Genes that are closely related to sugar metabolism were obtained from the annotation data of the passion fruit transcriptome，and expression levels were analyzed.The Gold cultivar displayed average glucose，fructose，and sucrose contents of 238.0，228.7，91.0 mg/g，respectively.The Mantianxing cultivar contained 229.7，226.3，55.6 mg/g，respectively.The Purple cultivar contained 218.3，210.0，86.4 mg/g，respectively.RT-qPCR was used to detect phosphoenolpyruvate carboxylation kinase，phospho fructose kinase，and pyruvate decarboxylase levels.It was found that the expression levels of the two genes encoding phosphoenolpyruvate carboxyl kinase and pyruvate decarboxylase were significantly different among different varieties.