Identification of putative genes to manipulate flavors in sweet orange fruit (citrus sinensis)

Fruit flavors have always played a significant role in consumer acceptability. Although fruit flavors consist of complex mixtures of volatile and soluble substances, certain sesquiterpenes, such as valencene, beta‐sinensal, alpha‐sinensal, and nootkatone are highlighted as key flavor compounds in citrus. Valencene is an important component of the flavor of the ripe, sweet orange fruit (citrus sinensis). TPS1 (XP_006477784.1) encodes valencene synthase, a sesquiterpene synthase catalyzing the generation of the orange aroma compound valencene. In the present study, protein-protein interactions (PPIs) network analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were applied on TPS1 to discover other components that have relationships with TPS1, as well as pathways which probably are associated with flavors biosynthesis. The PPIs network revealed that TPS1 is part of an interaction network that included 11 nodes and 49 edges. According to KEGG pathway enrichment analysis the genes included in the PPIs network were significantly enriched in the 3 pathways including sesquiterpenoid and triterpenoid biosynthesis (cit00909), metabolic pathways (cit01100), and biosynthesis of secondary metabolites (cit01110), which have been reported to be related to the biosynthesis of the flavor. To the best of our knowledge, there were no investigations about their role of the predicted genes in the biosynthesis of flavors in the citrus sinensis. Given that a very few genes are reported to be directly implicated in the biosynthesis of flavor fruit, these predicted genes may be considered potential candidates for improving the flavor of sweet orange and other fruits through metabolic engineering.