Effect of NaCI on nitrate reductase, glutamate dehydrogenase and glutamate synthase inVigna radiata calli

Abstract

The effect of NaC1 stress on the activities of nitrate reductase (NR), glutamate dehydrogenase (GDH) and glutamate synthase (GOGAT) in callus lines of Vigna radiata which differ in salt resistance, was studied at weekly intervals upto 28 d of growth. After 28 d, the NaC1 resistant callus (selected at 300 mM NaC1) at NaCI concentrations higher than 200 mM maintained higher NR activity than non-selected line. NaC1 stress also affects aminating and deaminating activities of GDH. The NADH-GDH activity in the presence of NaC1 was higher in the resistant than nonselected line. On the other hand, NAD-GDH activity in both the lines was completely inhibited after 7 d of growth. The increased activity of NADH-GDH in resistant calli may play a vital role in protecting the cells from toxic effect of increased endogenous level of ammonia which probably accumulates due to efficient NO 3-reduction. NADH-GOGAT activity was found to decrease under salt stress in both the callus lines. Nitrogen assimilation in salt-resistant calli under salt stress was found to be characterized by high NR and NADH-GDH activities, concomitantly with low GOGAT activity.

Over-expression of a glutamate dehydrogenase gene, MgGDH, from Magnaporthe grisea confers tolerance to dehydration stress in transgenic rice

“…4a, b). The result is consistent with the increased GDH activities observed by previous workers under stressful conditions of darkness (Laurière and Daussant 1983;Yamaya and Oaks 1987), senescence (Calle et al 1986), salinity (Gulati and Jaiwal 1996) and heavy metal toxicity (Mattioni et al 1997).…”

“…Although GDH catalyzes both the amination of 2-OG and the deamination of glutamate, it is the amination role that is enhanced under adverse environmental conditions (Robinson et al 1991;Gulati and Jaiwal 1996). Intracellular hyperammonia derived from senescence-induced high proteolytic activities (Masclaux et al 2000;Loulakakis et al 2002;Tercé-Laforgue et al 2004b) or abiotic stress (Lutts et al 1999;Hoai et al 2003) results in increased GDH amination activity in vivo.…”

“…Although GDH mediates the amination of 2-oxoglutarate (2-OG) and the deamination of glutamate, its amination activity role is more prominent under adverse environmental conditions (Robinson et al 1991;Gulati and Jaiwal 1996). In senescing leaves, GS and GOGAT decreased while GDH protein accumulated and the in vitro amination activity of GDH increased in tissues of senescing leaves (Masclaux et al 2000;Loulakakis et al 2002;Tercé-Laforgue et al 2004a, b).…”

Silicon improves salinity tolerance and affects ammonia assimilation in maize roots

“…The aminating role of GDH has been realized under stressful environmental conditions in Vigna radiata (Gulati & Jaiwal 1996). Various concentrations of Cd increased the GDH activity (Kumari et al 2011).…”

Novel Factors Affecting Shoot Culture of Chrysanthemum (Dendranthema × Grandiflora)

“…Although KUMAR et al (2000) noted an increase in aminating GDH activity with an increase in salt stress in vitro, no clear pattern or trend could be observed for deaminating GDH. GDH activity (Gulati & JaiWal, 1996), heavy metal (Cd and Ni) toxicity in Silene italica (Mattioni et al, 1997) and exposure to octane and benzene in Lolium perenne and Medicago sativa (sadunishvili et al, 2009). Dehydrogenases are important in plant metabolism since they generate reducing power for various biosynthetic processes; they also support redox cycling in the cell, allowing the plant to sustain stress (hare et al, 1998).…”