Exogenous Polyamine Treatment Prevents UV-A Induced Cellular Damage and Photoinhibition of Photosystem II in Lichen Physcia semipinnata (J. F. Gmel.) Moberg

In this study the protection ability of polyamines on Photosystem II (PSII), the proline content of the cells and necrosis formation induced by Ultraviolet-A irradiation were studied. Although 24 h Ultraviolet-A exposure decreased the photosynthetic quantum yield (Fv/Fm) ratio in Physcia semipinnata (J. F. Gmel.) Moberg, thalli that treated with 1 mM polyamine, especially spermidine and spermine, were slightly influenced by the UV-A exposure. It was also found that spd and spm treated samples had lower proline content than putrescine (put)-treated samples. Moreover, It was found that the samples that were treated with spd and spm had lower percentage of DNA damage than put-treated samples and non-treated groups. In this study, Ultraviolet-A induced DNA damage detected by acridine orange/ethidium bromide staining assay. The DNA damage in thalli of P. semipinnata was detected in situ in phycobiont layer after 24 h of Ultraviolet-A exposure, in contrast, polyamine-treated samples had a lower rate of necrotic cells.