Brown barcoded as red but reality is green! How epiphytic green algae confuse phycologists?

Abstract

Promises and perils of DNA barcoding are now well-known, but no studies have revealed the extent of taxonomic misidentification of algal specimens available in primary DNA sequence repositories. Our original objective was to assess the molecular identity of the ubiquitous brown alga Turbinaria ornata (Sargassaceae:, Fucales) from the southeast Indian coast. We extracted total genomic DNA from freshly collected algal thalli and sequenced the nuclear ribosomal DNA Internal Transcribed Spacer-1 (nrDNA ITS1) barcode locus. Following a BLASTn DNA sequence similarity search, the identity of our alga was Laurencia thyrsifera, a Pacific red alga that has never been reported in India, which came as a big surprise. Further analyses of BLAST hits using a robust phylogenetic framework of Bayesian Inference led to the conclusion that our sequence belonged to an epiphytic Ulvellacean green algal genus Ulvella, which might have been extracted and amplified with our universal ITS primers. This is the first report for Ulvella from India, and detection of this alga growing on Turbinaria. Our Bayesian analyses revealed that a number of GenBank accessions of this epiphyte are misidentified as red algae, which are published in some of the reputed phycological and botanical journals. This finding could have a profound impact on several of the fallacious phylogenetic conclusions arrived at in these publications. ? 2015 Dipartimento di Biologia, Universit? di Firenze.