Reisigl, a coccoid green microalga, is an oleaginous alga that can accumulate an unprecedentedly high level of arachidonic acid (ArA, 20:4w6)-rich triacylglycerols (TAG) under the growth stress of nitrogen starvation. ArA accounts for 68.0% of total fatty acids in TAG. How is ArA preferentially utilized for the biosynthesis of TAG? The Lands' cycle plays an important role in the composition change of fatty acids of phospholipids, thus altering the composition of fatty acids in TAG. Lysophosphatidylethanolamine acyltransferase (LPEAT), a key enzyme in the Lands' cycle, was the focus of the present study. was cloned using reverse transcription-PCR and 3°-and 5'-cDNA rapid amplification of cDNA ends technique. The full-length cDNA was 1303 bp long, and contained a 129-bp 5'-untranslated region (UTR) and 193-bp 3'-UTR. The length of the open read frame was 981 bp that encoded a 326-amino acid protein. The DNA sequence of with the isolated algal genomic DNA as a template, and it was 1871 bp long. Comparison of the cDNA and DNA sequences showed that possessed 6 introns that separated the coding sequence into 7 exons. Multiple sequence alignment and bioinformatics analysis of LPEATs from different species demonstrated that MiLPEAT possessed a phosphate acyltransferase domain, PlsC, thus suggesting that it was one member of the lysophospholipid acyltransferase (LPLAT) superfamily. MiLPEAT also had the 4 typical motifs, NH(x)₄D, GCxYVxR, FPEGT, and PVxPVx, which are characterized in the LPLAT superfamily. Both the prediction, as analyzed online by Wolfsport and Protein Prowler, and the presence of a dilysine motif at the carboxyl terminus of MiLPEAT, implied that MiLPEAT might reside at the algal endoplasmic reticulum and possibly participate in the secretion pathway. A neighbor-joining phylogeny was constructed on the basis of deduced amino acids of LPEATs from different species of plants. It illustrated that MiLPEAT was so different from LPEAT2 that they located at different clades due to their various characteristics of sequences. MiLPEAT was clustered phylogenetically with LPEAT1, suggesting their similar functions in the acylation of phospholipids. Quantitative real-time PCR detection pointed out that <0.05) at 8 h after treatment with nitrogen starvation in . By coincidence, the relative abundance of lysophosphatidylethanolamine (LPE) in the microalgal cells reduced by approximately 49% at an extreme significance level (<0.01) under the nitrogen starvation stress. The corresponding phosphatidylethanolamine (PE) generated from LPE as catalyzed by MiLPEAT, however, did not increase significantly. It is assumed that the net increase of PE under nitrogen starvation in was possibly utilized for TAG biosynthesis by the phospholipid DAG acyltransferase (PDAT), so that the content of TAG has been reported to increase. This research lays a foundation for us to understand the TAG and phospholipid biosynthetic pathway and how to regulate TAG synthesis in .