Cloning, subcellular localization and expression analysis of squalene epoxidase gene BsSE1 from Bletilla striata.

Squalene epoxidase catalyzes the oxidation of squalene to 2,3-oxo-squalene (BsSE1), and is the key rate limiting enzyme in the synthesis of triterpenoids and sterols in plants. This study focused on the basic aspects of BsSE1 including the sequence information, sub-cellular localization expression patterns of BsSE1. Using to the sequence information of Bletilla striata transcriptome, the full-length CDS of BsSE1 gene was amplified. The physicochemical properties and structural characteristics of BsSE1 protein were analyzed by bioinformatics analysis software, and vector was constructed to analyze the protein locations and expression patterns. The results showed that the CDS of BsSE1 gene was 1542 bp, encoding 513 amino acids. BsSE1 protein is a hydrophobic protein with two transmembrane domains but no signal peptides. It is localied in the endoplasmic reticulum membrane and belongs to the typical squalene epoxidase gene. BsSE1 has the closest genetic relationship with SE protein of Dendrobium officinale and Phalaenopsis equestris. The expression level of BsSE1 was higher in pseudobulblet of Bletilla striata seedlings, followed by roots, and lower in seedling stems. After SA induction, the expression of BsSE1 in Bletilla striata showed significant changes, increased first, then decreased, finally increase again. The results provide a basis for further study of this gene family in plants.