| Abstract
| - Phytoene synthase (Psy) catalyzing the dimerization of two molecules of geranylgeranyl pyrophosphate(GGPP) to phytoene may be rate limiting for the synthesis of β-carotene in Dunaliella salina. Toelucidate the carotenogenic pathway in D. salina, the complete Psy gene was first isolated by genomewalking technology and suppression PCR. Subsequently, RT-PCR was performed to obtain the PsycDNA of 1260 bp, which codes 420 amino acids. The Psy gene of total length of 2982 bp was foundto consist of five exons and four introns when compared with the cDNA sequence. The D. salina Psyamino acid has a 78−89% similarity with many other higher plants, but a phylogenic analysis showsa closer relationship between the microalgal and cyanobacterial Psy. Keywords: Dunaliella salina; phytoene synthase; sequence analysis; phylogenetic relationship
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