Abstract:

Five representative watermelon accessions were analyzed using UHPLC–MS/MS，and the primary metabolites of the high sugar cultivar‘97103’and low sugar wild accession‘PI296341’fruits were quantified using Gas Chromatography–Mass Spectrometery（GC–MS）. A total of 58 metabolites were identified，among which 27 compounds were significantly different. Raffinose content was much higher in the wild accession PI296341 than that in the cultivar 97103 fruits，and very few raffinose remained in the cultivar 97103 fruits. Analysis of differential metabolites and metabolic pathways revealed that cultivar 97103 fruits accumulated more metabolites from photosynthate unloading（raffinose and stachyose）and sucrose accumulating pathways，while the metabolites from the metabolism pathways of amino acids and organic acids and glucose-6-phosphate were the majority in PI296341 fruits. These findings provide important insights into the metabolic evolution from wild to cultivated species. The identification of metabolic properties can provide technical guidance for future improvement of watermelon quality.

Key words: watermelon, metabolomics, photosynthate unloading, sucrose accumulation, sugar metabolism pathway