[show abstract][hide abstract] ABSTRACT: Although Anabaena is one of the most prevalent planktonic freshwater genus in China, there are few taxonomic reports of Anabaena strains by morphology and genetics. In this study, morphological characteristics and phylogenetic relationships of seven
Anabaena strains isolated from two plateau lakes, Lakes Dianchi and Erhai, were investigated. Morphological characteristics such as
morphology of filament, cellular shapes and sizes, relative position of heterocytes and akinetes, and presence or absence
of aerotopes, were described for these seven strains. Phylogenetic relationships were determined by constructing 16S rRNA
gene tree using the neighbor-joining algorithm. The seven strains were morphologically identified as three groups, and phylogenetic
analysis based on 16S rRNA gene sequences also showed that these seven strains were in three groups. StrainsEH-2, EH-3, and
EH-4 were in groupA belonging to the Anabaenacircinalis and A.crassa group, and strainsDC-1, DC-2, and EH-1 were in groupB and identified as A.flos-aquae. Strain DC-3 without aerotopes was significantly different from the other isolated strains and was determined as A.cylindrica.