Effects of N supply on the accumulation of photosynthetic pigments and photoprotectors in <Emphasis Type="Italic">Gracilaria tenuistipitata</Emphasis> (Rhodophyta) cultured under UV radiation |
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Authors: | José Bonomi Barufi Nathalie Korbee Mariana C Oliveira Félix L Figueroa |
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Institution: | 1.Departamento de Botanica,Instituto de Biociências da Universidade de S?o Paulo,S?o Paulo,Brazil;2.Departamento de Ecología y Geología, Facultad de Ciencias,Universidad de Málaga,Málaga,Spain |
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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 NO3− 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 concentration-dependent
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 NO3−. 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. |
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