Clarifying the Fatty Acid Synthesis Gene Sequences of Sea Buckthorn Using High-Quality Genome Annotation

Sea buckthorn (Hippophae rhamnoides L.) is a valuable crop. Its berries are rich in bioactive compounds, including valuable fatty acids. We sequenced the transcriptomes of various organs/tissues of sea buckthorn variety Triumf, including roots, wood, bark, buds, leaves, and flowers. We then annotated the Triumf genome assembly using these data and previously obtained data for seeds and pulp at four fruit development stages. As a result, we predicted 25,915 gene models and 30,527 transcript models. Using the annotation, we identified three KAS I, six KAS II, two KAS III, one mtKAS, three FATA, five FATB, eight SAD, three FAD2, four FAD3, one FAD4, one FAD6, and five FAD7/8 genes. We also identified genes of these families in the annotated sea buckthorn genome assembly CNP0001846 (https://db.cngb.org). We analyzed domain and exon-intron structures and constructed phylogenetic trees for the genes identified in both genomes. The FATB (28610), SAD (18766), FAD2 (12459), FAD2 (21624), and FAD3 (24146) genes contained errors in the CNP0001846 genome assembly. These errors were absent in the corresponding genes of the Triumf genome assembly. Thus, using high-quality genome annotation, we obtained correct sequences of sea buckthorn genes of families involved in fatty acid synthesis.