Lipidome analysis and characterization of Buglossoides arvensis acyltransferases that incorporate polyunsaturated fatty acids into triacylglycerols. (November 2022)

• Record Type: Journal Article
• Authors: Parchuri, Prasad; Pappanoor, Anjali; Naeem, Abdulrahman; Durrett, Timothy P.; Welti, Ruth; R.V., Sreedhar
• Is Part Of: Plant science. Volume 324(2022)
• Publication Date: 2022-11
• Subjects: ALA α-linolenic acid; -- DAF Days After Flowering, -- DAG Diacylglycerol -- DGAT Diacylglycerol acyltransferase -- GLA γ-linolenic acid -- LA Linoleic acid -- PA Phosphatidic acid -- PC Phosphatidylcholine -- PDAT phospholipid: diacylglycerol acyltransferase -- QM Quadruple mutant -- SDA Stearidonic acid -- TAG Triacylglycerol; Acyltransferases -- Buglossoides arvensis -- α-linolenic acid -- γ-linolenic acid -- Stearidonic acid -- Triacylglycerol; Botany -- Periodicals; Botanique -- Périodiques; 580
• DOI: 10.1016/j.plantsci.2022.111445
• Languages: English
• ISSNs: 0168-9452

Abstract

Abstract: Buglossoides arvensis is a burgeoning oilseed crop that contains an unique combination of ω-3 and ω-6 polyunsaturated fatty acids (PUFA), constituting ~80–85% of seed triacylglycerols (TAGs). To uncover the critical TAG biosynthetic pathways contributing for high PUFA accumulation, we performed lipidome of developing seeds and characterized acyltransferases involved in the final step of TAG biosynthesis. During seed development, distribution of lipid molecular species in individual lipid classes showed distinct patterns from an early-stage (6 days after flowering (DAF)) to the middle-stage (12 and 18 DAF) of oil biosynthesis. PUFA-containing TAG species drastically increased from 6 to 12 DAF. The expression profiles of key triacylglycerol biosynthesis genes and patterns of phosphatidylcholine, diacylglycerol and triacylglycerol molecular species during seed development were used to predict the contribution of diacylglycerol acyltransferases (DGAT1 and DGAT2) and phospholipid: diacylglycerol acyltransferases (PDAT1 and PDAT2) to PUFA-rich TAG biosynthesis. Our analysis suggests that DGATs play a crucial role in enriching TAGs with PUFA compared to PDATs. This was further confirmed by fatty acid feeding studies in yeast expressing acyltransferases. BaDGAT2 preferentially incorporated high amounts of PUFAs into TAG, compared to BaDGAT1. Our results provide insight into the molecular mechanisms of TAG accumulation in this plant and identify target genes for transgenic production of SDA in traditional oilseed crops. Highlights: Buglossoides arvensis is the richest natural source of Stearidonic acid. Lipidome analysis during seed development showed distinct pattern of molecular species between lipid classes. Acyl-CoA dependent triacylglycerol biosynthesis is the major route for PUFA accumulation. Diacylglycerol acyltransferase 2 is the central player in the PUFA rich oil accumulation.