Resistance to photoinhibition of photosystem II and catalase and antioxidative protection in high mountain plants

Abstract

In leaves of three alpine high mountain plants, Homogyne atpina, Ranuncutus gtaciatis and Sotdanetta atpina., both photosystem II (PSIl) and the enzyme catalase appeared to be highly resistant to photoinactivation under natural field conditions. While the Dl protein of PSII and catalase have a rapid turnover in light and require continuous new protein synthesis in non-adapted plants, little apparent photoinactivation of PSII or catalase was induced in the alpine plants by translation inhibitors or at low temperature, suggesting that turnover of the Dl protein and catalase was slow in these leaves. In vitro PSII was rapidly inactivated in light in isolated thylakoids from H. alpina and R. gtaciatis. In isolated intact chloroplasts from R. gtaciatis., photoinactivation of PSII was slower than in thylakoids. Partially purified catalase from R. gtaciatis and S. alpina was as sensitive to photoinactivation in vitro as catalases from other sources. Catalase from H. atpina had, however, a 10-lbld higher stability in light. The levels of xanthophyll cycle earotenoids, of the antioxidants ascorbate and glutathione, and of the activities of catalase, superoxide dismutase and glutathione reductase were very high in S. atpina, intermediate in H. atpina, but very low in R. gtaciatis. However, isolated chloroplasts from all three alpine species contained much higher concentrations of ascorbate and glutathione than chloroplasts from lowland plants.

Adaptation of the Long-Lived Monocarpic Perennial, Saxifraga longifolia to High Altitude

“…Together with carotenoids, they also prevent PSII damage as a result of singlet oxygen attack (Munné-Bosch and Alegre, 2002;Falk and Munné-Bosch, 2010;Zbierzak et al, 2009;Kruk et al, 2014). A higher tocochromanol content, particularly of a-tocopherol, and an increased capacity for nonradiative dissipation of excitation energy by activation of the xanthophyll cycle have been found in highmountain plants, thus supporting such a role (Streb et al, 1997(Streb et al, , 1998(Streb et al, , 2003a(Streb et al, , 2003bGarcía-Plazaola et al, 2015). Furthermore, although the number of studies is still very limited for plants in their natural habitat, highmountain plants tend to accumulate large amounts of ABA (Bano et al, 2009), a phytohormone that is known to mediate the acclimation/adaptation of plants to temperature extremes by modulating the up-and down-regulation of numerous genes (Gilmour and Thomashow, 1991).…”

Photoperiod Affects the Phenotype of Mitochondrial Complex I Mutants

“…All enzymes were extracted from washed leaves in 50 mM potassium phosphate, pH 7.5, and measurements of activities of glycolate oxidase (EC 1.1.3.1), CAT (EC 1.11.1.6), APX (EC 1.11.1.11), and GR (EC 1.6.4.2) were as described by Streb et al (1997). For APX activity, only the cytoplasmic form was determined.…”

Oxygen Metabolism in Chloroplast

“…The concentration of ascorbate in chloroplasts is very high, achieving 10 -50 m (for review see Smirnoff, 2000), and even about 300 mM in alpine plants (Streb et al, 1997). Ascorbate can act as an effective quencher of O 2 •− with a high rate constant.…”