Nitrogen-containing compounds in several lichen species – representatives of Antarctic flora

Lichens are a stable, self-regulating association of fungus and algae or cyanobacteria. The composition of photobionts is associated with certain taxonomic groups of lichens. The most common groups of lichen photobionts are green algae and cyanoprokaryotes. Being well adapted, lichens play a prominent role in the Antarctic flora. The purpose of work is to study the nitrogen-containing composition of lichen thalli in the Antarctic flora. The samples of thalli were collected by doctor of biological sciences M.P.Andreev (Komarov Botanical Institute of the Russian Academy of Sciences) the January–April of 2015, 2016 and 2018 in different regions of the Antarctic. 11 lichen species with different photobiont type, including algae and/or cyanobacteria and belonging to the families Cladoniaceae, Parmeliaceae, Sphaerophoraceae, Ochrolechiaceae, Umbilicariaceae, Stereocaulaceae, Pannariaceae, and Collemataceae, were analysed. The work includes the data on the content of total nitrogen, soluble protein, free and protein amino acids in thalli of representatives of the Antarctic zone. There is a significant species variability by the content of total nitrogen, soluble protein, protein and free amino acids between thalli of Antarctic lichens. The studied parametersare foundfor a high variation coefficient. The median values of the samples for the content of amino acids differ from the mean values, which indicate a slight shift in the normalcy of the primary data distribution. Lichens with cyanoprokaryoteshave been identifiedto be prominent through a higher content of total nitrogen and protein amino acids compared to lichens with green algae as photobiont. The content of protein and free amino acidsis found to be closely correlatedwith the concentration of total nitrogen in thalli, whereas the correlation between the content of soluble protein and total nitrogen, as well as soluble protein and the sum of PAA and FAA is statistically insignificant. In general, the results obtained significantly deepen and expand the knowledge on the ecological and biological features of Antarctic lichens and their role in the nitrogen cycle of ecosystems.