Transcriptomic Analyses of Sambucus nigra L.:. Yield New Insights into Biosynthesis of Unsaturated Fatty Acid Biosynthesis

Sambucus nigra is a species that has been used in the practice of traditional Chinese medicine for thousands of years, with the high levels of omega-3 unsaturated fatty acids (UFAs) in S. nigra fruit playing a beneficial role in maintaining physiological homeostasis upon consumption. The precise mechanisms that underlie the biosynthesis of these UFAs in S. nigra, however, remain to be established. Accordingly, a whole transcriptomic analysis was herein conducted using fruits from three different stages of maturation using an Illumina RNA-Sequencing platform. This approach led to the identification of 459,026 unigenes that were assembled into 257,975 genes. KEGG pathway enrichment analyses of genes that were differentially expressed across different stages of S. nigra fruit maturation revealed that many of these genes were closely associated with lipid metabolism pathways. These findings enabled the identification of 259 unigenes potentially involved in de novo UFA biosynthesis. Notably, the key UFA synthesis-related genes FabG, SCD, DESA1, FAD2, and FAD8 were differentially expressed in different stages of fruit development. These results thus provide a strong foundation for subsequent research focused on S. nigra and have the potential to aid in the genetic engineering and breeding of crops containing higher levels of omega-3 UFAs.