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Open AccessArticle

Na+-Dependent High-Affinity Nitrate, Phosphate and Amino Acids Transport in Leaf Cells of the Seagrass Posidonia oceanica (L.) Delile

Department of Biología Vegetal, Campus Teatinos, Universidad de Málaga, 29071 Málaga, Spain
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Int. J. Mol. Sci. 2018, 19(6), 1570; https://doi.org/10.3390/ijms19061570
Received: 19 April 2018 / Revised: 21 May 2018 / Accepted: 22 May 2018 / Published: 24 May 2018
(This article belongs to the Special Issue Plasma-Membrane Transport)
Posidonia oceanica (L.) Delile is a seagrass, the only group of vascular plants to colonize the marine environment. Seawater is an extreme yet stable environment characterized by high salinity, alkaline pH and low availability of essential nutrients, such as nitrate and phosphate. Classical depletion experiments, membrane potential and cytosolic sodium measurements were used to characterize the high-affinity NO3, Pi and amino acids uptake mechanisms in this species. Net uptake rates of both NO3 and Pi were reduced by more than 70% in the absence of Na+. Micromolar concentrations of NO3 depolarized mesophyll leaf cells plasma membrane. Depolarizations showed saturation kinetics (Km = 8.7 ± 1 μM NO3), which were not observed in the absence of Na+. NO3 induced depolarizations at increasing Na+ also showed saturation kinetics (Km = 7.2 ± 2 mM Na+). Cytosolic Na+ measured in P. oceanica leaf cells (17 ± 2 mM Na+) increased by 0.4 ± 0.2 mM Na+ upon the addition of 100 μM NO3. Na+-dependence was also observed for high-affinity l-ala and l-cys uptake and high-affinity Pi transport. All together, these results strongly suggest that NO3, amino acids and Pi uptake in P. oceanica leaf cells are mediated by high-affinity Na+-dependent transport systems. This mechanism seems to be a key step in the process of adaptation of seagrasses to the marine environment. View Full-Text
Keywords: Posidonia; high-affinity transport; NO3 uptake; Pi uptake; Na+-dependent transport systems; Cytosolic Na+; amino acid transport Posidonia; high-affinity transport; NO3 uptake; Pi uptake; Na+-dependent transport systems; Cytosolic Na+; amino acid transport
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Rubio, L.; García-Pérez, D.; García-Sánchez, M.J.; Fernández, J.A. Na+-Dependent High-Affinity Nitrate, Phosphate and Amino Acids Transport in Leaf Cells of the Seagrass Posidonia oceanica (L.) Delile. Int. J. Mol. Sci. 2018, 19, 1570.

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