Integrated multi-omics analysis of developing ‘Newhall’ orange and its glossy mutant provide insights into citrus fragrance formation

Sesquiterpene valencene is dominant in flavedo tissues of sweet oranges and imparts a unique woody aroma. However, the interaction between the biosynthetic pathways of valencene and other nutritional compounds is less studied. Sesquiterpenoids were significantly accumulated in a previously reported glossy mutant of orange (MT) than the wild type (WT), especially valencene and caryophyllene. In addition, we identified several other pathways with variations at both the transcriptional and metabolic levels in MT. It's interesting to found those up-regulated metabolites in MT, such as eukaryotic lipids, kaempferol and proline also showed strong positive correlation with valencene along with fruit maturation while those down-regulated metabolites, such as phenylpropanoid coumarins and most of the modified flavonoids exhibited negative correlation. We then categorized these shifted pathways into the ‘sesquitepenoid-identical shunt’ and the sesquitepenoid-opposite shunt’ and confirmed the classification result at transcriptional level. Our results provide important insights into the connections between various fruit quality-related properties.