Bioinformatics and expression differences of GPAT in phaeodactylum tricornutum

Triacylglycerol is the main storage form of oil in plant cells. Glycerol-3-phosphate acyltransferase (GPAT) is the first rate-limiting enzyme in the process of TAG biosynthesis. In order to investigate the correspondence between the content of total lipid and the expression of PtGPAT under different temperature and light intensity, specific primers were designed based on the transcriptome data of Phaeodactylum tricornutum and the cDNA full-length sequence of GPAT was cloned by RT-PCR. The results showed that the cDNA sequence length of PtGPAT was 1743 bp, which contained an ORF of 1305 bp encoding 434 amino acids. Conservative structural domain analysis viewed that the GPAT belonged to lyso-phospholipid acyltransferases (LPLATs), and had the acyl-receptive binding bag consistent with GPAT protein characteristics. Phylogenetic tree analysis showed that PtGPAT had a close relationship with Thalassiosira oceanica. RFq PCR analysis was used to detect the expression of P. tricornutum under different light intensity and temperature conditions. The results showed that with the increase of temperature and light intensity, the expression of PtCPAt increased first and then decreased, which was consisitent with the change trend of total lipid content in P. tricornutum. The PtGPAT transcripts and the accumulation of total lipid of P. tricornutum was highest at 25℃, 37.5 μmol · m^-2 · s^-1 and significant correlation was found between PtGPAT expression level and the content of total lipid (r = 0.980, P < 0.05). In conclusion, our observation proved that the PtGPAT could be associated with lipid metabolic pathway of P. tricornutum. The study provides high quality genetic resources for the future use of genetic engineering to improve the content of oil in plants, and lays a theoretical foundation for further revealing the molecular regulatory mechanism for the synthesis of lipids in P. tricornutum. (authors)