Phylogenetic position of Dunaliella acidophila (Chlorophyceae) based on ITS and rbcL sequences

Abstract

Dunaliella acidophila is one of the most extreme acidophiles on earth and is able to survive in highly acidic habitats. This characteristic has made this organism the universal model for the study of abiotic stress. Although D. acidophila is currently circumscribed to the subgenus Pascheria within Dunaliella Teodoresco (Chlorophyceae), its taxonomic position has stirred controversy. The comparison of D. acidophila CCAP19/35 internal transcribed spacers (including ITS2 secondary structure analysis) and RuBisCo large subunit (rbcL) sequences with other Dunaliella species confirms that D. acidophila should maintain its phylogenetic position within the genus Dunaliella, suggesting its inclusion within the subgenus Dunaliella. Furthermore, the ITS1 and ITS2 data revealed that D. acidophila was highly divergent from the other freshwater species assessed, D. lateralis, with which it barely shares a 56.8% similarity.