Superoxide dismutase and ascorbate peroxidase genes in Antarctic endemic brown alga Ascoseira mirabilis (Ascoseirales, Phaeophyceae): data mining of a de novo transcriptome

Abstract

Abstract The Antarctic endemic brown alga Ascoseira mirabilis is physically and physiologically well adapted to the extreme polar environment. To better understand the molecular strategies associated with stress adaptation, the transcriptome of A. mirabilis was sequenced, and its antioxidant enzyme genes were identified and compared with other algae. A total of 126,576 unigenes with a mean length of 734 bp and N50 of 1174 bp was assembled from the transcriptome data. Phylogenetic analysis revealed that dramatic evolutionary changes had occurred in the brown algal superoxide dismutases (SODs) and class I peroxidases that were not consistent with the phylogeny of the species. Fe/Mn SODs are more prevalent in brown algae than in red and green algae. Two additional Fe-SODs in A. mirabilis were phylogenetically closely related to those of green algae, but not to those in other brown algae. We also identified three A. mirabilis ascorbate peroxidase (APx) genes that had a different origin from other brown algal APxs. The SOD and APx genes specifically identified in A. mirabilis will be crucial for understanding the evolution of the algal antioxidant enzymes that contribute to ecological success under extreme environmental conditions in the Antarctic region.