Heterologous expression of β-carotene hydroxylase in Dunaliella salina by Agrobacterium-mediated genetic transformation

Dunaliella salina is a halotolerant marine microalga, known for the accumulation of β-carotene. The BCH-type β-carotene hydroxylase plays a major role in the conversion of β-carotene to xanthophylls. The β-carotene hydroxylase from the chlorophycean microalga, Chlamydomonas reinhardtii was amplified, and the sequence alignment analysis showed that the amplified gene belongs to the group of BCH-type hydroxylases. The amplified β-carotene hydroxylase gene with rubisco promoter and chloroplast transit peptide was introduced into the genome of the D. salina by Agrobacterium-mediated genetic transformation. The carotenoid analysis showed a 3-fold increase of violaxanthin at growth stage and a 2-fold increase of zeaxanthin under stress conditions in transformed D. salina.