title: Protective effect of UV-A radiation during acclimation of the photosynthetic apparatus to UV-B treatment.
abstract: We examined the acclimation response of the photosynthetic apparatus of barley (Hordeum vulgare L.) to a combination of UV-A and UV-B radiation (UVAB) and to UV-B radiation alone. Our aim was to evaluate whether UV-A radiation prevents UV-B-induced damage to the photosynthetic apparatus and whether UV-A pre-acclimation is required to mitigate the negative influence of UV-B radiation. Barley plants were grown from seeds under low photosynthetically active radiation (50 μmol m(-2) s(-1)) either in the absence or presence of UV-A radiation (UVA- and UVA+ plants, respectively). After 8 days of development, plants were exposed simultaneously to UV-A and UV-B radiation for the next 6 days. Additionally, UVA- plants were exposed to UV-B radiation alone. The UVA+ plants had a higher CO2 assimilation rate near the light-saturation region (A(N)) and a higher content of both total chlorophylls (Chls) and total carotenoids than the UVA- plants. Chls content, A(N), the potential quantum yield of photosystem II (PSII) photochemistry (F(V)/F(M)), the capacity of light-induced thermal energy dissipation and the efficiency of excitation energy transfer within PSII remained the same or even increased in both UVA+ and UVA- plants after UVAB treatment. On the contrary, exposure of UVA- plants to UV-B radiation itself led to a reduction in all these characteristics. We revealed that the presence of UV-A radiation during UVAB treatment not only mitigated but completely eliminated the negative effect of UV-B radiation on the functioning of the photosynthetic apparatus and that UV-A pre-acclimation was not crucial for development of this UV-A-induced resistance against UV-B irradiation.
authors.affiliation: Faculty of Science, University of Ostrava, 30. dubna 22, CZ-701 03, Ostrava 1, Czech Republic; Global Change Research Centre, Academy of Sciences of the Czech Republic, Bělidla 986/4a, CZ-603 00, Brno, Czech Republic. Electronic address: michal.stroch@osu.cz.
authors.forename: Michal
authors.initials: M
authors.lastname: Štroch
authors.affiliation: Faculty of Science, University of Ostrava, 30. dubna 22, CZ-701 03, Ostrava 1, Czech Republic.
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Materová
authors.affiliation: Faculty of Science, University of Ostrava, 30. dubna 22, CZ-701 03, Ostrava 1, Czech Republic.
authors.forename: Daniel
authors.initials: D
authors.lastname: Vrábl
authors.affiliation: Faculty of Science, University of Ostrava, 30. dubna 22, CZ-701 03, Ostrava 1, Czech Republic; Global Change Research Centre, Academy of Sciences of the Czech Republic, Bělidla 986/4a, CZ-603 00, Brno, Czech Republic.
authors.forename: Václav
authors.initials: V
authors.lastname: Karlický
authors.affiliation: Faculty of Science, University of Ostrava, 30. dubna 22, CZ-701 03, Ostrava 1, Czech Republic; Global Change Research Centre, Academy of Sciences of the Czech Republic, Bělidla 986/4a, CZ-603 00, Brno, Czech Republic.
authors.forename: Ladislav
authors.initials: L
authors.lastname: Šigut
authors.affiliation: Faculty of Science, University of Ostrava, 30. dubna 22, CZ-701 03, Ostrava 1, Czech Republic.
authors.forename: Jakub
authors.initials: J
authors.lastname: Nezval
authors.affiliation: Faculty of Science, University of Ostrava, 30. dubna 22, CZ-701 03, Ostrava 1, Czech Republic; Global Change Research Centre, Academy of Sciences of the Czech Republic, Bělidla 986/4a, CZ-603 00, Brno, Czech Republic.
authors.forename: Vladimír
authors.initials: V
authors.lastname: Špunda
mesh_terms: D000222:Adaptation, Physiological; D001467:Hordeum / Q000502:physiology / Q000528:radiation effects*; D010788:Photosynthesis; D014466:Ultraviolet Rays
keywords: Barley (Hordeum vulgare L.); Chlorophyll fluorescence; Photosynthesis; Photosynthetic pigments; UV-A radiation; UV-B radiation