PHYLOGENETIC RELATIONSHIP AMONG VARIOUS STRAINS OF DUNALIELLA (CHLOROPHYCEAE) BASED ON NUCLEAR ITS rDNA SEQUENCES

Abstract

Phylogenetic analyses of 15 strains representing 8 taxa of Dunaliella ( D. salina, D. bardawil, D. pseudosalina, D. tertiolecta, D. parva, D. viridis, D. peircei , and D. lateralis ) belonging to both subgenera and all sections of the genus were carried out using the sequences of the nuclear rDNA spacers (internal transcribed spacer [ITS-1 ؉ ITS-2]). The ITS data agreed with the traditional data in that D. lateralis (from subgenus Pascheria ) is only distantly related to the seven taxa of the subgenus Dunaliella. The ITS data also supported the monophyly of the subgenus Dunaliella. Within the subgenus Dunaliella , sequence data resolved five phylogenetic groups; some isolates of D. parva and D. salina separated into different clades containing other species. For example, D. parva UTEX 1983 (section Dunaliella ) grouped with D. viridis CONC 002 (section Virides ); the former has more nucleotides in common with D. viridis (93.2% similarity) than to its conspecifics (85.6% similarity). Likewise, the strains of D. parva CCMP 362 and CCAP 19 ⁄ 9 (section Dunaliella ), the three strains of D. tertiolecta (section Tertiolectae ), and the one strain of D. peircei (section Peirceinae ) formed a strong phylogenetic clade (99%-100% support). Dunaliella salina UTEX 200 is more closely related to D. pseudosalina CONC 010 than to its conspecifics (95% similarity), even though the two taxa differ markedly physiologically. The results revealed that D. parva UTEX 1983 has been misidentified and should be renamed as D. viridis. Similarly, the strains of D. parva CCAP 19 ⁄ 9 and CCMP 362 and the strain UTEX 2192 of D. peircei should be renamed as D. tertiolecta. More physiological and molecular work needs to be done to elucidate the correct taxonomic position of D. salina UTEX 200 and D. pseudosalina CONC 010. Finally, the high ITS sequence variability found among the various strains of D. salina underlines the importance of further work to elucidate the species status in this complex taxon.

Characterization of Dunaliella salina strains by flow cytometry: a new approach to select carotenoid hyperproducing strains

“…González et al (1998) showed a low intraspecific genetic variability in strains from different countries. However, an important correspondence among intraspecific genetic variability and morphological and physiological behaviour has been found in D. salina, though the morphologic traditional criteria of taxonomical classification present diverse limitations (Cifuentes et al 2001;Gómez and González, 2001;González et al 2001). In the present work, it can be underlined the wide morphological and physiological variation found among native strains isolated from various saltworks in close geographical vicinity.…”

“…However, carotenoid productivity from D. salina is fundamentally determined by other parameters, such as cellular division rate and biomass production (Hejazi and Wijffels, 2003). This approach to the potential productivity of the strains we propose is more comprehensive than the simple evaluation of carotenoid cellular contents because as well as this variable, we include other parameters such as chlorophyll/carotenoid ratio, cellular size and complexity, which are related with growth rate in D. salina (Gómez et al 1999;Giordano, 2001;Gómez and González, 2001). With this new approach to select carotenoid hyperproducing strains of D. salina it is possible to directly estimate the potential growth rates and carotene productivity in complex samples with different strains.…”

Biogeographic analysis of ribosomal RNA clusters from marine bacterioplankton

“…DNA sequence comparisons) could show that some accepted approaches to delineating species of protists (e.g. morphogenesis) combined different taxonomic units (Gonzalez et al 2001). It is therefore not surprising to observe more accurate patterns of distribution with more constrained parameters for phylogenic delineation.…”

Monitoring of uncultured Dunaliella sp. in an Egyptian solar saltern field based on RuBisCO-encoding gene cbbL

“…These studies have encompassed the 18S rRNA genes and the internal transcribed spacer regions, ITS and have been based on gene sequence comparisons as well as on restriction fragment length polymorphism studies (Gomez and Gonzalez, 2001;Assunção et al, 2012). Little correlation was found between the molecular data and the traditional morphological-physiological attributes to delineate species within the genus Dunaliella (González et al, 1999(González et al, , 2001.…”