Skip to main content
Fig. 6 | BMC Plant Biology

Fig. 6

From: Effects of glucose on the uptake and metabolism of glycine in pakchoi (Brassica chinensis L.) exposed to various nitrogen sources

Fig. 6

A simplified model of the effect of high glucose on glycine (Gly) metabolism in root and shoot. Gly is transported in root by amino acid transporters, and it is converted to serine (Ser) catalysed by SGAT. Ser can be converted to other amino acids (AAs), and NH4 + can be converted to glutamine (Gln) catalysed by glutamine synthetase (GS). In addition, Gln with 2-oxoglutarate (2-OG) can be converted to glutamate (Glu), which is catalysed by glutamine synthetase-glutamate synthase (GOGAT). Glu can be converted to aspartic acid (Asp) catalysed by glutamic oxalacetic transaminase (GOT), and Asp can be assimilated into asparagine (Asn). Additionally, NH4 + can be assimilated to Glu by glutamate dehydrogenase (GDH) and Glu can be converted to alanine (Ala) by glutamic pyruvic transaminase (GPT). 15N-labelled Gly was rarely detected in the shoot, indicating that little glycine was transported to shoot. Gln, Glu, Asn, and Asp are the four main amino acids transported from root to shoot, of which Gln is the most important. AA metabolism in the shoot is similar to that in the root. In the root, Gly is high at high glucose, whereas the levels of Ser and Asn are lower compared with the optimal level, indicating that the conversion of Gly to Ser under high glucose level limits Gly metabolism in the root. In the shoot, Asn, Gln, and Glu are low at high glucose, which may be attributable to poor metabolism in root

Back to article page