Úloha chloroplastové glutaminsyntetázy GS2 u Arabidopsis thaliana

Kobercová, Eliška

Glutamine synthetase (GS) is a key enzyme of plant nitrogen metabolism, catalyzing the assimilation of ammonium into glutamine. Ammonium originates both from soil uptake and from internal metabolic processes, including nitrate reduction, phenylpropanoid metabolism, remobilization of nitrogen resources, amino acid catabolism, and photorespiration. Although ammonium is an essential nitrogen source, its overaccumulation is toxic to plants and leads to chlorosis and growth inhibition. In plants, GS isoforms are classified by subcellular localization into plastidic GS2 (encoded by GLN2 in Arabidopsis thaliana) and cytosolic GS1 (encoded by GLN1;1-GLN1;5). While GS2 is essential for photorespiration in several species (Wallsgrove et al., 1987; Migge and Becker, 2000; Orea et al., 2002; Ding et al., 2023), its function in A. thaliana remained unclear at the beginning of this project. In this PhD study, I prepared knock-out mutants in GLN2 using CRISPR/Cas9 mutagenesis and showed that mutation of GLN2 in A. thaliana causes a slight but clear photorespiratory phenotype. Unfortunately, the team of Dr. Paula Melo overtook us in publishing these results. However, their findings (Ferreira et al., 2019) were later completely discredited in the work of Lee et al. (2022), who questioned the T-DNA insertion lines...

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