Abstract:

Effects of NaCl-stress on ammonia assimilation enzymes and the related parameters were determined in the roots of three rice (Oryza sativa L.) cultivars differing in salt tolerance. The results showed that the activities of glutamine synthetase (GS) and NADH-dependent glutamate synthase (NADH-GOGAT), as well as the levels of soluble protein decreased under high concentration salt. The influence extent was in accordance with Zao-hua 2 (salt-sensitive), Jin-zhu 1 (normal cultivar) and Jin-dao 779 (salt-resistant), which was consistent with their salt-tolerance. Nevertheless, under the stress of high salt concentration, NADH-dependent glutamate dehydrogenase (NADH-GDH) activity of Zao-hua 2 and Jin-zhu 1 was induced significantly, but that of Jin-dao 779 did not increase remarkably. The salt stress led to the accumulation of total soluble sugar (TSS) in the root of Jin-zhu 1 and Jin-dao 779 in different degree. The level of TSS in Zao-hua 2 changed with different NaCl concentrations. Among the cultivars observed, content of proline increased in different degree, but under high salt concentrations, it had a more marked rise in the roots of salt-sensitive cultivars.

Key words: glutamine synthetase (GS), glutamate synthase (GOGAT), glutamate dehydrogenase (GDH), rice, salt stress