Transgenic manipulation of triacylglycerol biosynthetic enzymes in B. napus alters lipid-associated gene expression and lipid metabolism

Pan Liao,Kent D Chapman,Trevor Romsdahl,Mee-Len Chye,Tamara Lechon,John L Harwood,Ruth E Bates,Helen Woodfield,Stepan Fenyk,Emma Wallington,Tony Fawcett,Simon Scofield

doi:10.1038/s41598-022-07387-x

Abstract

Oilseed rape (Brassica napus) is an important crop that is cultivated for the oil (mainly triacylglycerol; TAG) it produces in its seeds. TAG synthesis is controlled mainly by key enzymes in the Kennedy pathway, such as glycerol 3-phosphate acyltransferase (GPAT), lysophosphatidate acyltransferase (LPAT) and diacylglycerol acyltransferase (DGAT) but can also be produced from phosphoglycerides such as phosphatidylcholine (PC) by the activity of the enzyme phospholipid: diacylglycerol acyltransferase (PDAT). To evaluate the potential for these enzymes to alter oil yields or composition, we analysed transgenic B. napus lines which overexpressed GPAT, LPAT or PDAT using heterologous transgenes from Arabidopsis and Nasturtium and examined lipid profiles and changes in gene expression in these lines compared to WT. Distinct changes in PC and TAG abundance and spatial distribution in embryonic tissues were observed in some of the transgenic lines, together with altered expression of genes involved generally in acyl-lipid metabolism. Overall our results show that up-regulation of these key enzymes differentially affects lipid composition and distribution as well as lipid-associated gene expression, providing important information which could be used to improve crop properties by metabolic engineering.

Highlights

Oilseed rape (Brassica napus) is an important crop that is cultivated for the oil it produces in its seeds
Since we had previously shown that lipid assembly in B. napus was important for regulation of oil accumulation[3,6], in this study we examined lipid profiles and changes in global gene expression in transgenic B. napus lines overexpressing three important enzymes for triacylglycerol formation: glycerol-3-phosphate acyltransferase 9 (GPAT9), lysophosphatidate acyltransferase (LPAT/LPAAT) and phospholipid:diacylglycerol acyltransferase (PDAT)
The three homozygous transgenic lines analysed in this study overexpressed transgenes encoding glycerol 3-phosphate acyltransferase 9 (GPAT9) from Arabidopsis thaliana (GPAT-OE), lysophosphatidic acid acyltransferase from Tropaeolum majus (LPAT-OE) and phospholipid: diacylglycerol acyltransferase[1] from Arabidopsis thaliana (PDAT-OE)

Summary

Introduction

Oilseed rape (Brassica napus) is an important crop that is cultivated for the oil (mainly triacylglycerol; TAG) it produces in its seeds. TAG synthesis is controlled mainly by key enzymes in the Kennedy pathway, such as glycerol 3-phosphate acyltransferase (GPAT), lysophosphatidate acyltransferase (LPAT) and diacylglycerol acyltransferase (DGAT) but can be produced from phosphoglycerides such as phosphatidylcholine (PC) by the activity of the enzyme phospholipid: diacylglycerol acyltransferase (PDAT). To evaluate the potential for these enzymes to alter oil yields or composition, we analysed transgenic B. napus lines which overexpressed GPAT, LPAT or PDAT using heterologous transgenes from Arabidopsis and Nasturtium and examined lipid profiles and changes in gene expression in these lines compared to WT. Expression of two heterologous genes for GPAT in Arabidopsis produced small increases in TAG accumulation[14] while efforts to boost supply of its substrate in B. napus increased oil formation[15,16]

Methods

Results

Discussion

Conclusion