DNA signaturing derived from the internal transcribed spacer 2 (ITS2): a novel tool for identifying Desmodesmus species (Scenedesmaceae, Chlorophyta)

Abstract

The freshwater green algal genus Desmodesmus contains many cryptic species that are difficult to identify using morpho–anatomy. This study analyzed 310 ITS2 sequences related to Desmodesmus species from GenBank and developed a new tool named DNA signaturing. DNA signaturing is a species identification method using signature sequences specific for each species or strain group within the genus Desmodesmus. These signature sequences had 18–33 nucleotides in length. This tool could exactly identify 19 species and 24 strain groups of Desmodesmus. In addition, a signature sequence, AGA GGC TTA AAC TGG GAC C, was specific for almost 90% of Desmodesmus strains and could represent the genus Desmodesmus. A strain MLC1 isolated from freshwater in Da Nang, Vietnam, was identified as Desmodesus pseudoserratus by this tool. DNA signaturing tool described here showed the highest efficacy for identifying strains and a remarkable ability to accurately classify cryptic species in the genus Desmodesmus.