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Physiological responses of eelgrass (Zostera marina) to ambient stresses such as herbicide, insufficient light, and high water temperature

Author:
Mochida, Kazuhiko, Hano, Takeshi, Onduka, Toshimitsu, Ito, Katsutoshi, Yoshida, Goro
Source:
Aquatic toxicology 2019 v.208 pp. 20-28
ISSN:
0166-445X
Subject:
Zostera marina, cell walls, energy, glutamine, growth retardation, herbicides, leucine, myo-inositol, photosynthesis, protein degradation, stress response, sucrose, water temperature
Abstract:
This study aimed to elucidate the biological responses of eelgrass (Zostera marina) to artificially induced stresses such as herbicide (Irgarol 1051, Irg) exposure, insufficient light, and high water temperature (27 ± 1.0 °C) by evaluating growth inhibition, photosynthetic activity, and metabolomic profiles. After 14 days, all treatments inhibited growth, but photosynthetic activity was only reduced in the Irg-exposed group. In the Irg-exposed and insufficient light groups, the metabolomic profiles were characterized by decreased levels of sugar (sucrose) and increased levels of amino acids such as glutamine, glycine, and leucine. Biochemical and ultrastructural analyses revealed that the loss of sugar-derived metabolic energy was compensated for by energy generated during autophagic protein degradation. Furthermore, the level of myo-inositol, which has various biological roles and participates in several cellular processes such as cell wall synthesis, stress response, and mineral nutrient storage, was markedly increased in the Irg-exposed and insufficient light groups. A combination of metabolomic analysis with other analyses such as measurement of photosynthetic activity might further elucidate the response of eelgrass to ambient stresses in the natural environment.