Assessing 18S rDNA Diversity of the Chlorophytes among Various Freshwaters of the Central Black Sea Region

Abstract

In this study, diversity of unicellular chlorophytes isolated from various freshwater habitats in the Central Black Sea Region were assessed by the molecular phylogenetic methods. In order to determine diversity, water samples were collected from freshwater habitats including Cernek Lagoon (Kizilirmak Delta-Samsun), Kurtun Estuary (Samsun), Sarikum Lagoon (Sinop) and a freshwater pond in Boyabat (Sinop). Axenic cultures were obtained with re-streaking the isolates from enrichment cultures on solid growth media. For characterisation of isolates, phylogenetic analyses depending on nucleotide sequences of small subunit of nuclear ribosomal DNA (18S rDNA) was used besides morphological observations. In morphological observations upon closely related unicellular chlorophytes, there were no significant morphological differences among the isolates. As a result of phylogenetic analyses, our isolates were appeared in three distinct lineages which were related with Chlamydomonadaceae (isolates 103I2 and C301), Chlorellaceae (isolate B4Riv) and Scenedesmaceae (isolates SIN-CON and N603) families. Our results in this study clearly indicates the deficiency of the morphological observations and also the necessity of the molecular methods for true identification of chlorophytes. Additionally, it provides the first 18S rDNA haplotypes of chlorophyte families stated above from Turkish freshwaters to international databases.