Genome-Wide Identification and Comparative Expression Profile Analysis of the Long-Chain Acyl-CoA synthetase (LACS) Gene Family in Two Different Oil Content Cultivars of Brassica napus

Long-chain acyl-CoA synthetase (LACS) is one of the key enzymes involved in fatty acid metabolism, including phospholipid biosynthesis, triacylglycerol (TAG) biosynthesis, and fatty acid β-oxidation in plants. However, the characterization of LACSs family in seed oil biosynthesis of Brassica napus (B. napus) remains unknown. In the present study, we performed a comprehensive genome-wide analysis of this gene family in B. napus, and 34 B. napus LACS genes (BnaLACSs) were identified. Phylogenetic analysis classified the BnaLACS proteins into four groups (A, B, C, and D), which were supported by highly conserved gene structures and consensus motifs. RNA-Sequencing (RNA-Seq) and qRT-PCR combined analysis revealed that 18 BnaLACSs (BnaLACS1-2, 1-3, 1-4, 1-9, 1-10, 2-1, 2-2, 4-1, 4-2, 6-1, 6-2, 6-4, 7-1, 7-2, 8-1, 8-2, 9-3, and 9-4) were highly expressed in developmental seeds. Comparative expression analysis between extremely high oil content (P1-HO) and low oil content (P2-LO) B. napus cultivars revealed that BnaLACS6-4, BnaLACS9-3, and BnaLACS9-4 may be involved in fatty acid synthesis in chloroplast, and BnaLACS1-10 and 4-1 may play a vital role in lipid biosynthesis in B. napus, which is important for further seed oil accumulation in oilseed rape. The present study provides important information for functional characterization of BnaLACSs in seed oil metabolism in B. napus.