Different strategies of nitrogen acquisition in two tropical seagrasses under nitrogen enrichment

Tropical marine seagrasses live in environments with low nutrient concentrations. However, as land development intensifies along tropical coastlines, the marine environment in which these organisms grow is becoming more nutrient-rich. Nitrogen (N) uptake, assimilation, translocation and storage unde...

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Bibliographic Details
Published in:The New phytologist 2019-08, Vol.223 (3), p.1217-1229
Main Authors: Viana, Inés G., Saavedra-Hortúa, Daniel Arturo, Mtolera, Matern, Teichberg, Mirta
Format: Article
Language:English
Subjects:
Alismatales - metabolism
amino acids
Ammonium
Ammonium compounds
Analysis of Variance
Aquatic plants
Assimilation
Biological Transport
Cymodocea serrulata
enzymatic activity
Eutrophication
Glutamate-ammonia ligase
Glutamate-Ammonia Ligase - metabolism
Glutamine
Grasses
Hydrocharitaceae - metabolism
Indo‐Pacific
Land development
Marine environment
Mineral nutrients
Models, Biological
Nitrate reductase
Nitrate Reductase - metabolism
Nitrates
Nitrogen
nitrogen (N) uptake
Nitrogen - metabolism
Nitrogen enrichment
Nutrient concentrations
Nutrient enrichment
Nutrient uptake
Nutrients
Reductases
Rhizomes
Sea grasses
Seagrasses
Storage
Thalassia hemprichii
Tissue
Translocation
Tropical Climate
Uptake
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Summary:Tropical marine seagrasses live in environments with low nutrient concentrations. However, as land development intensifies along tropical coastlines, the marine environment in which these organisms grow is becoming more nutrient-rich. Nitrogen (N) uptake, assimilation, translocation and storage under a diversity of N sources in enriched conditions were investigated in two tropical seagrass species, Cymodocea serrulata and Thalassia hemprichii, from an oligotrophic marine environment. Both seagrasses were able to take up different inorganic and organic N sources through their above- and belowground tissues when enriched with high N concentrations. The uptake rates of T. hemprichii were generally higher than C. serrulata in leaves and rhizome, whereas root uptake was systematically higher in C. serrulata. Acropetal and basipetal translocation was observed in both species. Reduction and assimilation of N, measured in terms of their nitrate reductase and glutamine synthetase activity, were correlated with nitrate and ammonium uptake rates, respectively. Cymodocea serrulata showed a tendency to immediately use the available N, whereas T. hemprichii allocated more N in assimilation and storage investment. The responses of these seagrasses to N-enrichment demonstrate their ability to adapt to over-enrichment by varying N sources in the first step of the eutrophication process.
ISSN:0028-646X
1469-8137
DOI:10.1111/nph.15885