Silencing UDP-glucose pyrophosphorylase gene in Phaeodactylum tricornutum affects carbon allocation

•Suppression of UGPase resulted in significant decreases in chrysolaminarin content.•Suppression of UGPase led to increases in lipid synthesis.•UGPase is a rate-limiting enzyme in chrysolaminarin biosynthesis.•UGPase plays an important role and the allocation of carbon.•Ugp is a good candidate gene for allocating overall carbon flux in diatoms.

The effects of the suppression of UDP-glucose pyrophosphorylase (UGPase) on chrysolaminaran biosynthesis and carbon allocation were investigated in Phaeodactylum tricornutum. The 69% decrease in UGPase activity was accompanied by a 4.89 fold reduction in Ugp transcript abundance. Inactivation of UGPase in P. tricornutum led to a significant decrease in chrysolaminaran content and an increase in lipid synthesis. These findings suggest that UGPase is a rate-limiting enzyme and may play an important role in chrysolaminarin biosynthesis and carbon allocation. Our results support a theoretical deduction that Ugp is a good candidate for improving lipid synthesis in diatoms.