Resistance of Primary Photosynthesis to Photoinhibition in Antarctic Lichen Xanthoria elegans: Photoprotective Mechanisms Activated during a Short Period of High Light Stress.

The Antarctic lichen, Xanthoria elegans, in its hydrated state has several physiological mechanisms to cope with high light effects on the photosynthetic processes of its photobionts. We aim to investigate the changes in primary photochemical processes of photosystem II in response to a short-term photoinhibitory treatment. Several chlorophyll a fluorescence techniques: (1) slow Kautsky kinetics supplemented with quenching mechanism analysis; (2) light response curves of photosynthetic electron transport (ETR); and (3) response curves of non-photochemical quenching (NPQ) were used in order to evaluate the phenomenon of photoinhibition of photosynthesis and its consequent recovery. Our findings suggest that X. elegans copes well with short-term high light (HL) stress due to effective photoprotective mechanisms that are activated during the photoinhibitory treatment. The investigations of quenching mechanisms revealed that photoinhibitory quenching (qIt) was a major non-photochemical quenching in HL-treated X. elegans; qIt relaxed rapidly and returned to pre-photoinhibition levels after a 120 min recovery. We conclude that the Antarctic lichen species X. elegans exhibits a high degree of photoinhibition resistance and effective non-photochemical quenching mechanisms. This photoprotective mechanism may help it survive even repeated periods of high light during the early austral summer season, when lichens are moist and physiologically active.

Assessment of air pollution genotoxicity by molecular markers in the exposed samples of Pseudevernia furfuracea (L.) Zopf in the province of Kayseri (Central Anatolia).

In living organisms heterogenous air pollutants are considered as a major source of DNA damage. In this study, we aimed to describe the DNA changes in Pseudevernia furfuracea (L.) Zopf samples exposed to pollution at various sites in Kayseri by RAPD (random amplified polymorphic DNA) analysis in order to reveal the pattern of genetic variation influenced by the environmental pollution. The study area is characterized by the presence of numerous industrial activities, such as steel works, glassworks, shipbuilding, and metallurgical, mechanical, chemical and food industries. Control samples were collected from Cat forest (Sivas) and exposed to pollution in dry and wet seasons in the province of Kayseri located in Central Anatolia. Results indicated that heterogeneous pollutants might have contributed to the changes in the band patterns obtained by RAPD analysis, reflecting the occurrence of DNA damage in the control samples.

Characterisation of α-chitin extracted from a lichenised fungus species Xanthoria parietina.

Lichens are symbiotic associations formed mainly by ascomycete fungi and green algae or cyanobacteria. The presence of chitin in the fungal cell wall has been revealed by previous studies. Considering the presence of fungi in the lichens, this work determines the presence of chitin in a cosmopolitan lichen species Xanthoria parietina. In this study, chitin was derived from a lichen species for the first time and its physicochemical properties were determined by Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy and elemental analysis. The dry weight chitin content of X. parietina was 4.23%, and this chitin was in the α-form. The crystalline index value of the lichen chitin was calculated as 70.1%. The chitin from X. parietina had a smooth surface.