Nitrate assimilation during the anaerobic germination of rice: expression of ferredoxin-dependent glutamate synthase

✍ Scribed by Monica Mattana; Immacolata Coraggio; Ida Brambilla; Alcide Bertani; Remo Reggiani

• Publisher: Springer-Verlag
• Year: 1996
• Tongue: English
• Weight: 519 KB
• Volume: 199
• Category: Article
• ISSN: 0032-0935
• DOI: 10.1007/bf00196883

✦ Synopsis

Ferredoxin-dependent glutamate synthase (Fd-GOGAT; EC 1.4.7.1) is the last enzyme involved in the pathway of nitrate assimilation in higher plants. This paper describes the synthesis and expression of the enzyme in anaerobic coleoptiles of rice (Oryza sativa L.) and its regulation by exogenous nitrate. The activity of Fd-GOGAT was strongly inhibited by cycloheximide between 4 and 9 d of anaerobic germination. The addition of nitrate slightly increased, in the first 5 h, the specific activity of Fd-GOGAT as well as the amount of a 160-kDa protein specifically immunoprecipitated with anti-Fd-GOGAT serum. Northern blot analysis, performed with a specific riboprobe, showed the presence of mRNA of the expected size and the inductive effect of nitrate. The role of Fd-GOGAT is discussed in relation to the anaerobic assimilation of nitrate by rice coleoptiles.