Abstract: The effects of rapamycin (RPM) on fucoxanthin content and the correlation between photosynthesis and fucoxanthin accumulation in Phaeodactylum tricornutum were studied in this paper. Results indicated that 2.5-10 mmol/L RPM promoted the growth of P. tricornutum cells and the accumulation of fucoxanthin content. When the RPM concentration was 5 mmol/L, the content of fucoxanthin was the highest, which increased 40%. RT-qPCR analysis results showed that 24 h after RPM treating, the expression level of pds gene was consistent with the change trend of fucoxanthin content in P. tricornutum. The expression of lcyb gene showed a downward-regulated trend compare with that of the treatment group. The expression levels of psbA, rbcL, rbcS and fcpb genes related to the photosynthetic were significantly up-regulated. Principal component analysis showed that the accumulation of fucoxanthin content was positively correlated with the expression levels of photosynthetic rbcS, psbA, and rbcL genes.This result provided a theoretical basis for further exploring the biosynthesis mechanism of fucoxanthin in P. tricornutum and the correlation between photosynthesis and fucoxanthin content.

Key words: rapamycin, Phaeodactylum tricornutum, fucoxanthin, photosynthesis