Publicação: UV-radiation effects on photosynthesis, photosynthetic pigments and UV-absorbing substances in three species of tropical lotic macroalgae
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2018-09-01
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Brazilian Soc Plant Physiology
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Freshwater algae inhabiting shallow waters are most effectively affected by UV radiation. The aim of this study was to analyze the photosynthetic performance (parameters derived of chlorophyll fluorescence), chlorophyll a concentrations and the content of UV-absorbing compounds (mycosporine-like aminoacids-MAAs) in three tropical lotic macroalgae, Cladophora glomerata (Chlorophyta), Spirogyra sp. (Streptophyta) and Sirodotia delicatula (Rhodophyta) in response to UV radiation exposure under laboratory conditions. Experiments were performed under three treatments: (1) PAR (400-700 nm), P; (2) PAR + UVA (320-700 nm), PA; (3) PAR + UVA + UVB (280-700 nm), PAB. Cladophora glomerata and Spirogyra sp., typical sun-adapted lotic macroalgae, had distinct responses to UV radiation exposure. A more pronounced decrease of F (v)/F (m) and increase of NPQ under UVA than UVAB was observed, whereas chlorophyll a content was lower under UVAB in C. glomerata. Spirogyra sp. had a decrease of photosynthetic yields (Delta F/F (m)' and F (v)/F (m)) under PAR, indicating that UVAB radiation may have a positive effect on the photosynthetic apparatus. Surprisingly, S. delicatula, a shade-adapted alga, exhibited less sensitivity to UV exposure. These results suggest that the presence of MAAs (shinorine and palythine) in S. delicatula is a significant shield of protection against UV radiation.
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Theoretical And Experimental Plant Physiology. Campinas: Brazilian Soc Plant Physiology, v. 30, n. 3, p. 181-192, 2018.
