Effects of Ultraviolet Radiation (UVA+UVB) on Young Gametophytes ofGelidium 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.

Physiological performance by growth rate, pigment and protein content of the brown seaweed <em>Sargassum filipendula</em> (Ochrophyta: Fucales) induced by moderate UV radiation exposure in the laboratory

“…In a previous study using Sargassum cymosum C. Agardh as a biological model to evaluate the combined effects of UV radiation and salinity, Polo et al (2014a) found that UVA and UVB together in low doses such as the ones used herein stimulated the growth rate, leading to an increase in the amount of mitochondria, which could support the metabolic energy demand required for this process. Indeed, studies with different algal species at low doses of UV radiation show that the UV level modulates diverse physiological responses besides growth through up-or downregulation, such as induction of Chl a, phenolic compounds and antioxidant activity (Polo et al 2014a), alteration in putrescine/spermidine ratio (Polo et al 2014b), variation of photosynthetic performance and accessory pigments (Simioni et al 2014, Schmidt et al 2015, and ultrastructural organization (Bouzon et al 2012, Pereira et al 2017.…”

Accumulation of Glucosinolates in Broccoli

“…Recent studies have revealed that light influenced the accumulation of phytochemicals such as vitamin C, phenolic compounds and carotenoids, as well as glucosinolates [125][126][127][128]. It has been reported that UV-B radiation caused an induction of glucosinolate accumulation, especially of glucoraphanin and 4-methoxy glucobrassicin in broccoli sprouts and florets [129,130].…”

Effects of Ultraviolet Radiation (UVA + UVB) on Germination of Carpospores of the Red MacroalgaPyropia acanthophora var. brasiliensis(Rhodophyta, Bangiales): Morphological Changes

“…This problem was done with the Rio 92 Conference and, consequently, an emission of polluting gases by the diminished world, looking for a recovery of the ozone layer. However, the studies show that the thickness of the ozone layer is recovering, but an intensity of UVR that distances from terrestrial ecosystems has not decreased , to high levels of UVR in South America .…”