Abstract
BackgroundTriacylglycerols (TAGs) are the main composition of plant seed oil. Long-chain acyl-coenzyme A synthetases (LACSs) catalyze the synthesis of long-chain acyl-coenzyme A, which is one of the primary substrates for TAG synthesis. In Arabidopsis, the LACS gene family contains nine members, among which LACS1 and LACS9 have overlapping functions in TAG biosynthesis. However, functional characterization of LACS proteins in rapeseed have been rarely reported.ResultsAn orthologue of the Arabidopsis LACS2 gene (BnLACS2) that is highly expressed in developing seeds was identified in rapeseed (Brassica napus). The BnLACS2-GFP fusion protein was mainly localized to the endoplasmic reticulum, where TAG biosynthesis occurs. Interestingly, overexpression of the BnLACS2 gene resulted in significantly higher oil contents in transgenic rapeseed plants compared to wild type, while BnLACS2-RNAi transgenic rapeseed plants had decreased oil contents. Furthermore, quantitative real-time PCR expression data revealed that the expression of several genes involved in glycolysis, as well as fatty acid (FA) and lipid biosynthesis, was also affected in transgenic plants.ConclusionsA long chain acyl-CoA synthetase, BnLACS2, located in the endoplasmic reticulum was identified in B. napus. Overexpression of BnLACS2 in yeast and rapeseed could increase oil content, while BnLACS2-RNAi transgenic rapeseed plants exhibited decreased oil content. Furthermore, BnLACS2 transcription increased the expression of genes involved in glycolysis, and FA and lipid synthesis in developing seeds. These results suggested that BnLACS2 is an important factor for seed oil production in B. napus.
Highlights
Triacylglycerols (TAGs) are the main composition of plant seed oil
The amino acid sequence of the BnLACS2 protein was aligned with 24 Long-chain acyl-coenzyme A synthetases (LACSs) sequences from different species, including B. napus, Gossypium hirsutum, Arabidopsis thaliana, Saccharomyces cerevisiae, and Homo sapiens
High levels of BnLACS2 activity modifies the expression of Fatty acids (FAs) and lipid synthesis genes in developing seeds From the above results, we found that modification of BnLACS2 activity levels affected glycolytic gene expression, but the mechanism for that effect is unknown
Summary
Triacylglycerols (TAGs) are the main composition of plant seed oil. Long-chain acyl-coenzyme A synthetases (LACSs) catalyze the synthesis of long-chain acyl-coenzyme A, which is one of the primary substrates for TAG synthesis. The genes encoding longchain acyl-CoA synthetase (LACS, EC 6.2.1.3) catalyze the formation of acyl-CoA thioesters from free FAs in the presence of CoA, ATP, and Mg2+. It is a critical process in FA metabolism in prokaryotes and eukaryotes, and involves a two-step reaction. In the diatom Phaeodactylum tricornutum, a lower photosynhetic organism, there were five putative LACSs (PtACSL1–5), and only two of which were able to restore growth, facilitate exogenous FA uptake, and enhance lipid accumulation in the yeast double mutant, FAA1ΔFAA4Δ [17]. Those studies have provided a molecular basis for the study of LACSmediated FA and lipid metabolism in different organisms
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