Abstract
Frustulia was used as a model genus to test four candidate markers (D1-D2 LSU rDNA, V4-SSU rDNA, rbcL-3 P, and COI-5 P) for DNA barcoding of diatoms. The Frustulia strains included in the study were primarily isolated from Europe and New Zealand.
In agreement with previous reports, the results suggest that a dual-locus barcode comprising a partial sequence of the large ribosomal subunit (LSU) and a partial sequence of the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (rbcL) is the best option for DNA barcoding of diatoms. Unfortunately, this approach is limited by the lack of a distinct barcode gap for these markers.
Overall, the results of this study suggest that Frustulia species cannot currently be resolved without the use of additional non-molecular evidence. Effective use of DNA barcoding will require a better understanding of the mechanisms that generate and maintain genetic diversity in diatoms.