Phylogenetic position and morphology of lichenized Trentepohliales (Ulvophyceae, Chlorophyta) from selected species of Graphidaceae

The order Trentepohliales comprises a diverse and widespread group of green algae in temperate and tropical regions. The free-living representatives of this order have been investigated in more detail, whereas less is known about the trentepohlialean photobionts of lichens. Selected lichen species of the family Graphidaceae (Graphis propinqua, Graphis scripta, Graphis submarginata) from different climatic regions were chosen for the isolation of trentepohlialean photobionts. Three different nutrient media (modified Bold's Basal medium, modified Woods Hole MBL medium, optimal Haematococcus medium) were tested for the cultivation of these algae. The differences of the growth reactions of the isolated photobionts in culture were studied examining morphological characteristics, reproductive strategies and variations in carotenoid accumulation. The phylogenetic positions of the photobionts were investigated using sequences of the 18S rRNA gene, ITS region, and rbcL gene. Three photobiont strains were identified as Printzina lagenifera and one as Trentepohlia sp. according to the phylogenetic data and the morphological observations under culture conditions.