phytoplanktons and dna barcoding: characterization and molecular analysis of phytoplanktons on the persian gulf.

background and objectives: phytoplanktons are organisms with a very high diversities and global distribution in different habitats. the high distribution of phytoplankton is due to ecological flexibility and their ability to tolerate different climatic conditions and environmental stress. phytoplankton is the most sensitive biological indicators of water resources. the purpose of this study was to identify the phytoplankton species with emphasis on dna bar-coding method.  the study of phytoplankton variation and the identification of their species composition can provide useful information about the water quality. materials and methods: in this research project, a clone library of the ribosomal small subunit rna gene (18s rdna) in the nuclear genome was constructed by pcr using a and ssu-inr1 primers, and then, after examining the clones, selected clones were sequenced. results: eleven analyzed sequences were identified correctly and characterized by a similarity search of the genbank database using blast (ncbi). in this study, we revealed a wide range of taxonomic groups in the alveolata (ciliphora and dinophyceae), stramenopiles (bacillariophyta and bicosoecida), rhodophyta and haptophyceae. moreover, we found species of fungi and metazoa (arthropoda). most of the sequences were previously unknown but could still be assigned to important marine phyla. conclusion: clone library of 18s rdna is an accurate method to identify marine specimens and it is recommended as an efficient method for phylogenic studies in marine environments. there seems to be a high diversity and abundance of small eukaryotes in the marine regions of persian gulf.