Species-specific oligonucleotide probes for macroalgae: molecular discrimination of two marine fouling species of Enteromorpha (Ulvophyceae)

The green seaweeds Enteromorpha intestinalis and E. compressa are important fouling organisms commonly found in polluted and nutrient-enriched marine and brackish water habitats, where they are used in environmental monitorin g. Discrimination of the two species is extremely difficult because of over lapping morphological characters. In this study a quick molecular method fo r species identification was developed based on the nuclear rDNA ITS2 seque nce data of 54 E. intestinalis samples and 20 E. compressa samples from a w ide geographical range. Oligonucleotide probes were designed for species-sp ecific hybridization to dot-blots of the PCR-amplified ITS1, 5.8S gene and ITS2 fragment of both E. intestinalis and E. compressa. Specificity of the oligonucleotide probes was confirmed by tests with taxonomically diverse sp ecies that could morphologically be confused with E. intestinalis or E. com pressa. This is the first use of species-specific probes for macroalgae. Th e restriction endonuclease NruI digested specifically the amplified PCR pro duct from E. compressa into two fragments detectable on agarose gels, but n o suitable restriction sites were identifiable in the PCR product of E. int estinalis.