Do polyamines alter the sensitivity of lichens to nitrogen stress?

• Published in: Ecotoxicology and environmental safety 2009-07, Vol.72 (5), p.1331-1336
• Main Authors: Pirintsos, S.A., Munzi, S., Loppi, S., Kotzabasis, K.
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Ammonium Sulfate - metabolism; Chlorophyll - metabolism; Dose-Response Relationship, Drug; Environmental Monitoring; Environmental Pollutants - metabolism; Evernia prunastri; Lichen sensitivity/tolerance; Lichens - metabolism; Light; Light intensity; Nitrates - metabolism; Nitrogen; Nitrogen - metabolism; Photosynthesis; Photosynthetic efficiency; Photosystem II Protein Complex - metabolism; Polyamines; Polyamines - metabolism; Potassium Compounds - metabolism; Stress, Physiological; Time Factors; Xanthoria parietina
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2009.03.001

The sensitivity of lichens measuring photosynthetic efficiency and polyamines as modulator of nitrogen stress tolerance was investigated. Two lichen species with a markedly different tolerance to nitrogen compounds, namely Evernia prunastri (L.) Ach. and Xanthoria parietina (L.) Th.Fr., were incubated with deionized water (control) and solutions of KNO 3, NH 4NO 3 and (NH 4) 2SO 4 and then exposed to different light conditions. The F v/ F m parameter (maximum quantum efficiency of photosystem II) was used as stress indicator. The results showed that F v/ F m values, in the produced experimental conditions, were independent from the light gradient. Photosynthetic efficiency of E. prunastri was impaired by high ammonium concentrations, while nitrate had no effect; X. parietina was hardly influenced by nitrogen compounds. External supply of polyamines reduced the sensitivity of E. prunastri, while polyamine inhibitors reduced the tolerance of X. parietina to NH 4 +, suggesting that polyamines play an important role in modulating the sensitivity/tolerance to nitrogen stress.