Molecular Mechanisms Regulating the Oil Biosynthesis in Olive (<i>Olea europaea</i> L.) Fruits Revealed by Transcriptomic Analysis

Abstract

As one of the most important crops for oil, olive (Olea europaea L.) is well-known worldwide for its commercial product “virgin olive oil” containing high-content fatty acids and many secondary metabolites. The molecular mechanisms underlying the enhanced oil content in olive remain unclear. To further investigate the molecular mechanisms of olive oil biosynthesis, we selected two olive cultivars, i.e., Kalinjot (JZ) and Coratina (KLD), at three maturity stages (MI-1, MI-3, and MI-6) for transcriptomic analysis based on Nanopore sequencing. Significant differences were observed in oil content between JZ and KLD during three maturity stages. Enrichment analysis revealed significant enrichment of differentially expressed genes (DEGs) in metabolic pathways of photosynthesis, amino acid biosynthesis, response to stress, and energy metabolism, in particular, fatty acid metabolism. A total of 170 (31.54% of 539 genes involved in oil synthesis) DEGs were further investigated based on expression analysis to identify their molecular functions in oil biosynthesis in olive. A co-expression network based on 714 transcription factors and their targeted genes in oil biosynthesis was constructed. Our study provided novel experimental evidence to investigate the molecular mechanisms of olive oil biosynthesis and to improve the breeding of olive varieties with enhanced oil contents.

Keywords

• oil biosynthesis
• olive fruit
• transcriptomic analysis
• fatty acid metabolism
• transcription factor
• co-expression network