Specific transcription of sodium-dependent pyruvate transporter 2 increases carbon allocation into plastid glycolysis and fatty acid synthesis with high oil production in Lindera glauca seeds.

BASS (Bile acid/sodium symporter) contribute greatly to pyruvate transport for oil biosynthesis. This work focused on determining critical BASS and revealing function in controlling oil biosynthesis in Lindera glauca seeds. A combination of global analysis of oil biosynthesis-related plastidial transporters and quantitative-comparison of transcription of BASS family members with oil content was conducted in L. glauca seeds across 9 differential accessions or developmental stages to determine BASS2 specific for seed oil accumulation, with BASS2-directed regulation model constructed for partitioning carbon into plastid glycolysis. BASS2 gene and its own promoter were isolated, and heterologous expression in Arabidopsis was driven respectively by the constitutive 35S and self-specific promoters. LgBASS2 overexpression, particularly controlled by native promoter, enhanced seed biomass and oil production, facilitated uptake of glycolytic metabolites into plastid, increased the amounts of plastid glycolytic metabolites and FA synthetic precursors, and upregulated transcription of key regulatory enzymes or proteins (involving sucrose cleavage, plastid transporter, glycolysis, FA biosynthesis, triacylglycerol assembly and lipid droplet budding). Our findings highlighted a significance of own promoter-controlled transcriptional expression of LgBASS2 to promoting seed development with high oil production, and provided new molecular regulation target of LgBASS2 and its own promoter to future bioengineering seed oil production.