title: Effects of ultraviolet radiation (UVA+UVB) on young gametophytes of Gelidium floridanum: growth rate, photosynthetic pigments, carotenoids, photosynthetic performance, and ultrastructure.
abstract: This study investigated the effects of radiation (PAR+UVA+UVB) on the development and growth rates (GRs) of young gametophytes of Gelidium floridanum. In addition, photosynthetic pigments were quantified, carotenoids identified, and photosynthetic performance assessed. Over a period of 3 days, young gametophytes were cultivated under laboratory conditions and exposed to photosynthetically active radiation (PAR) at 80 μmol photons m(-2) s(-1) and PAR+UVA (0.70 W m(-2))+UVB (0.35 W m(-2)) for 3 h per day. The samples were processed for light and electron microscopy to analyze the ultrastructure features, as well as carry out metabolic studies of GRs, quantify the content of photosynthetic pigments, identify carotenoids and assess photosynthetic performance. PAR+UVA+UVB promoted increase in cell wall thickness, accumulation of floridean starch grains in the cytoplasm and disruption of chloroplast internal organization. Algae exposed to PAR+UVA+UVB also showed a reduction in GR of 97%. Photosynthetic pigments, in particular, phycoerythrin and allophycocyanin contents, decreased significantly from UV radiation exposure. This result agrees with the decrease in photosynthetic performance observed after exposure to ultraviolet radiation, as measured by a decrease in the electron transport rate (ETR), where values of ETRmax declined approximately 44.71%. It can be concluded that radiation is a factor that affects the young gametophytes of G. floridanum at this stage of development.
authors.affiliation: Plant Cell Biology Laboratory, Department of Cell Biology, Embryology and Genetics, Federal University of Santa Catarina, Florianópolis, SC, Brazil.
authors.forename: Carmen
authors.initials: C
authors.lastname: Simioni
authors.forename: Eder C
authors.initials: EC
authors.lastname: Schmidt
authors.forename: Marthiellen R de L
authors.initials: MR
authors.lastname: Felix
authors.forename: Luz Karime
authors.initials: LK
authors.lastname: Polo
authors.forename: Ticiane
authors.initials: T
authors.lastname: Rover
authors.forename: Marianne
authors.initials: M
authors.lastname: Kreusch
authors.forename: Debora T
authors.initials: DT
authors.lastname: Pereira
authors.forename: Fungyi
authors.initials: F
authors.lastname: Chow
authors.forename: Fernanda
authors.initials: F
authors.lastname: Ramlov
authors.forename: Marcelo
authors.initials: M
authors.lastname: Maraschin
authors.forename: Zenilda L
authors.initials: ZL
authors.lastname: Bouzon
mesh_terms: D002338:Carotenoids / Q000096:biosynthesis; D002473:Cell Wall / Q000528:radiation effects / Q000648:ultrastructure; D002734:Chlorophyll / Q000096:biosynthesis; D004579:Electron Transport / Q000528:radiation effects; D004583:Electrons; D056130:Gametogenesis, Plant / Q000502:physiology / Q000528:radiation effects*; D008854:Microscopy, Electron; D010788:Photosynthesis / Q000502:physiology / Q000528:radiation effects*; D010798:Phycocyanin / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D010799:Phycoerythrin / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D000461:Rhodophyta / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects* / Q000648:ultrastructure; D014466:Ultraviolet Rays
chemical_list: C002497:allophycocyanin; D010798:Phycocyanin; D010799:Phycoerythrin; D002734:Chlorophyll; D002338:Carotenoids