Silencing 1,3-β-glucan synthase gene promotes total lipid production and changes fatty acids composition by affecting carbon flow distribution in Phaeodactylum tricornutum

To clarify the effect of 1,3-beta-glucan (known as chrysolaminarin) synthase (PtBGS) on carbon flow distribution, expression of 1,3-beta-glucan synthase gene (Ptbgs) was silenced by RNA interference in Phaeodactylum tricornutum. The results showed that the chrysolaminarin content in all transgenic strains was significantly lower than that in the wild-type (WT), while the total lipid content increased to varying degrees. Importantly, the decrease in chrysolaminarin content was significantly correlated with the increase in total lipid content. There was no significant difference in the protein content between all the transgenic strains and WT. Thus, PtBGS mainly affected the distribution of carbon flow in total lipids and polysaccharides, mainly chrysolaminarin. Silencing Ptbgs changed the fatty acids composition, and specifically promoted polyunsaturated fatty acids production and reduced monounsaturated fatty acids content, but had only a little effect on saturated fatty acids content. Interestingly, the growth of transgenic strains was not influenced while the lipid content increased, indicating that Ptbgs silencing may be an effective strategy to improve lipid production in diatoms.

Automated summary

Silencing of the 1,3-beta-glucan synthase gene (Ptbgs) in Phaeodactylum tricornutum resulted in significantly lower chrysolaminarin content and increased total lipid content. This study demonstrates that Ptbgs mainly affects carbon flow distribution, leading to changes in fatty acid composition and increased production of polyunsaturated fatty acids.