A survey of Polytomella (Chlorophyceae, Chlorophyta) strains in public culture collections. Issue 4 (8th July 2016) - MacDonald, Shelley M.
Abstract : Polytomella is a genus of colorless green algae in the Reinhardtinia clade of the Chlamydomonadales, which has proven useful for a broad range of studies particularly those exploring the evolutionary loss of photosynthesis and mitochondrial genomics/biochemistry. Although 13 Polytomella strain accessions are currently available from public culture collections, the taxonomic status and redundancy of many of these strains is not clear because of possible mix‐ups, deficient historical records, and incomplete molecular data. This study therefore considers previously available and/or new cox1 and mitochondrial DNA telomere sequences from all 13 Polytomella strain accessions. Among four of these, namely P. parva SAG 63‐3, P. piriformis SAG 63‐10, P. capuana SAG 63‐5, and P. magna SAG 63‐9, cox1 and mitochondrial telomere regions are both highly divergent between strains. All of the remaining nine Polytomella strain accessions have cox1 sequences that are identical to that of P. parva SAG 63‐3 and although five of these have a mitochondrial telomere haplotype that is identical to that of P. parva SAG 63‐3, the remaining four have one of three different haplotypes. Among the 10 strains with identical cox1 sequences, we suggest that three of the telomere haplotypes are associated with distinct geographical isolates of Polytomella and the fourth evolved from one of these isolates during 50 years of active culture.