Antarctic moss: surviving ultraviolet radiation in a changing climate

The Antarctic ozone hole increases ultraviolet-B radiation (UV-BR) at the Earth’s surface, and is linked to increased wind speed, altered precipitation and snow deposition patterns. The influence of UV-BR was investigated in three co-occurring moss species from East Antarctica: two cosmopolitan (Ceratodon purpureus (Hedw.) Brid. and Bryum pseudotriquetrum (Hedw.) Gaertn., B. Mey. & Scherb) and the endemic (Schistidium antarctici (Cardot) L.I. Savicz & Smirnova). A comprehensive field study concurrently measured a range of physiological parameters, indicative of both plant stress and photoprotection, over summer 2002/03. Changes in these parameters were compared to natural fluctuations in environmental variables, including incident UV-BR, water availability and temperature. To complement the field study, and assess interactions between UV-BR and water, UV tolerance of the three species was compared in both dry and hydrated moss in a light-box irradiation study. UV tolerance was assessed as DNA damage; cyclobutane pyrimidine dimers (CPDs) and (6-4)-photoproducts were determined using enzyme linked immunosorbent assays. Bulk UV absorbing compounds (UVACs), including anthocyanins, were measured spectroscopically, using acidified methanol and alkaline hydrolysis to extract from the cytosol and cell wall respectively. Photosynthetic rates were calculated from chlorophyll fluorescence data, and chloroplastic pigments were quantified using high performance liquid chromatography..