Effects of N supply on the accumulation of photosynthetic pigments and photoprotectors in Gracilaria tenuistipitata (Rhodophyta) cultured under UV radiation

Abstract

We have studied the effects of nitrate supply under photosynthetic active radiation (PAR) plus ultraviolet radiation (UVR) exposure on photosynthetic pigments (chlorophyll a and carotenoids), photoprotective UV screen mycosporine-like amino acids (MAAs), and photosynthetic parameters, including the maximum quantum yield (F v /F m ) and electron transport rate (ETR) on the red agarophyte Gracilaria tenuistipitata. Apical tips of G. tenuistipitata were cultivated under ten different concentrations of NO 3 − for 7 days. It has been shown that G. tenuistipitata cultured under laboratory conditions has the ability to accumulate high amounts of MAAs following a nitrate concentrationdependent manner under PAR+UVR. Two MAAs were identified, shinorine and porphyra-334. The relative concentration of the first increased under high concentrations of nitrate, while the second one decreased. The presence of antheraxanthin is reported for the first time in this macroalgae, which also contains zeaxanthin, lutein, and β-carotene. The accumulation of pigments, photoprotective compounds, and photosynthetic parameters of G. tenuistipitata is directly related to N availability. All variables decreased under low N supplies and reached constant maximum values with supplements higher than 0.5 mM NO 3 − . Our results suggest a high potential to acclimation and photoprotection against stress factors (including high PAR and UVR) directly related to N availability for G. tenuistipitata.

Effects of solar UV radiation on photosynthetic performance of the diatom Skeletonema costatum grown under nitrate limited condition

“…The NPQ, an important strategy for phytoplankton to rapidly (seconds to minutes) regulate photochemistry, is one of the first lines of defense that Kashino et al (2002) and Fujiki et al (2003) also indicated that the NPQ process is of importance to maintain the photosynthetic activity of phytoplankton. On the other hand, the substances, that need N for their synthesis, e.g., UV-screening compounds like mycosporine-like amino acids were recorded to increase with increasing nitrogen levels (Litchman et al 2002, Korbee et al 2010, Barufi et al 2011 and might also attribute to the higher UVR sensitivity in LN-than in HN-grown cells. The diatom grown under N-limited condition exhibited higher sensitivity to UVR than that grown under N-replete condition, based on the changes in the photochemical quantum yield and NPQ, which indicates that the N limitation exacerbates the effects of UVR on its photosynthetic performance and stimulate its NPQ.…”

Effects of light quality on reproduction, growth and pigment content of <em>Gracilaria birdiae</em> (Rhodophyta: Gracilariales)

“…First, the high amount of PE in G. birdiae cultivated under BL could act as a system of energy dissipation, together with a possible xanthophyll cycle, a phenomenon which has been related to energy dissipation (Demmig-Adams 2003). The occurrence of this cycle in G. birdiae was suggested by Ursi et al (2003), and an incomplete xanthophyll cycle was proposed for G. tenuistipitata by Barufi et al (2011). A second photoprotective mechanism involves the position of different phycobiliproteins in the phycobilisome.…”

Pengaruh Iradiasi Ultraviolet terhadap Multiplikasi Tunas Aksiler dan Kadar Klorofil Anyelir (Dianthus caryophyllus L.)

“…Di bawah cekaman ultraviolet tanaman mengorbankan kloroplasnya dalam rangka melindungi sel. Iradiasi ultraviolet kemungkinan mempengaruhi pigmen fotosintesis, di samping itu juga menghambat sintesisnya atau mempengaruhi enzim-enzim yang terlibat dalam jalur sintesis klorofil (Barufi et al, 2010).…”

“…Walau demikian, tanaman perlakuan ini ternyata mampu untuk melakukan perbaikan. Kelompok tanaman anyelir yang disimpan pada cahaya ternyata dapat melakukan pemulihan sendiri dengan bantuan cahaya yang dikenal dengan metode fotoreaktivasi (Barufi et al, 2010). Bahkan pada tanaman yang disimpan di tempat gelap pun juga muncul tunas aksilernya.…”