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Glutamine synthetase (GS), a key enzyme in plant nitrogen metabolism, is closely related to nitrogen remobilization. However, how GS isoforms participate in nitrogen remobilization remains unclear. Here, the spatiotemporal expression of the <i>TaGS</i> gene family after anthesis was investigated, and the results showed that TaGS1;1 was mainly encoded by <i>TaGS1;1-6A</i>, while the other isozymes were mainly encoded by <i>TaGS</i> localized on the A and D subgenomes. <i>TaGS1;2-4A/4D</i> had the highest expression level, especially in rachis and peduncle. Furthermore, immunofluorescence showed TaGS1;2 was located in the phloem of rachis and peduncle. GUS (β-glucuronidase) staining confirmed that <i>ProTaGS1;2-4A/4D::GUS</i> activity was mainly present in the vascular system of leaves, roots, and petal of <i>Arabidopsis</i>. Ureides, an important transport form of nitrogen, were mainly synthesized in flag leaves and transported to grains through the phloem of peduncle and rachis during grain filling. <i>TaAAH</i>, which encodes the enzyme that degrades ureides to release NH₄⁺, had a higher expression in rachis and peduncle and was synchronized with the increase in NH₄⁺ concentration in phloem, indicating that NH₄⁺ in phloem is from ureide degradation. Taking the above into account, TaGS1;2, which is highly expressed in the phloem of peduncle and rachis, may participate in N remobilization by assimilating NH₄⁺ released from ureide degradation.