Exogenous proline and glycinebetaine increase NaCl-induced ascorbate–glutathione cycle enzyme activities, and proline improves salt tolerance more than glycinebetaine in tobacco Bright Yellow-2 suspension-cultured cells

Up-regulation of antioxidant and glyoxalase systems by exogenous glycinebetaine and proline in mung bean confer tolerance to cadmium stress

“…However, the mechanisms by which proline and betaine protect plant cells under heavy metal stress have remained unsolved. Recent studies in plants have demonstrated that exogenous application of betaine or proline at high concentration (1-20 mM) enhance tolerance to abiotic oxidative stress (Park et al 2006;Hoque et al 2007;Huang et al 2009;Islam et al 2010;Hossain and Fujita 2010). Extensive research findings support the idea that coordinated induction and regulation of the antioxidant and glyoxalase pathway enzymes are necessary to obtain substantial tolerance against oxidative stress.…”

Proline and Glycinebetaine Ameliorated NaCl Stress via Scavenging of Hydrogen Peroxide and Methylglyoxal but Not Superoxide or Nitric Oxide in Tobacco Cultured Cells

“…Exogenously applied proline and betaine suppress cell death in BY-2 cells accompanied by decreased oxidative damages to lipid membranes and protein under 200 mM NaCl stress, 8,12) suggesting that both compounds are efficient at mitigating most of the deleterious consequences of salt stress after 4 d of incubation, 12) but proline mitigates the inhibitory effects of salt stress more than betaine due to differences in the antioxidant defense and MG detoxification systems. 8,28,29) In the present study, we attempted to clarify the protective mechanisms of proline and betaine in cultured tobacco cell responses to salt stress.…”

“…The higher accumulation of H 2 O 2 and O 2 À in NaCl-stressed cells might be associated with decreased activities of H 2 O 2 -and O 2 À -scavenging antioxidant enzymes, inhibiting cell growth and increasing cell death. 8,12,28,29) Tight regulation of H 2 O 2 and O 2 À homeostasis is necessary to protect cells against the damaging effects of salt stress. Proline is a potent ROS scavenger associated with inhibition of apoptosis-like cell death and increasing activity of catalase.…”

“…12) Decreased levels of H 2 O 2 in the NaCl-stressed cells due to proline and betaine might be more important than those of O 2 À and NO in avoiding cellular damage and improving cell growth. The reduction in H 2 O 2 accumulation due to proline and betaine may be a reason for the increased activity and/or expression of H 2 O 2 -scavenging antioxidant enzymes and/or genes 8,12,28,29) that can inhibit the accumulation of extra H 2 O 2 in cells.…”

“…18) There is increasing evidence that both proline and betaine increase antioxidant defense mechanisms and improve stress tolerance in plants as well as in cultured cells. 9,10,18,[25][26][27] We have found that exogenous application of both proline and betaine increases intracellular proline and betaine contents, 11) which leads to the suppression of cell death and improvement of salt tolerance in tobacco Bright Yellow-2 (BY-2) cells via increments in the antioxidant defense and MG detoxification systems, 8,12,28,29) but protective mechanisms of proline and betaine in plant responses to salt stress remain to be clarified. The present study was therefore conducted to investigate the effects of exogenous proline and betaine on intracellular H 2 O 2 , O 2 À , NO, and MG levels and the mRNA levels of glutathione peroxidase (GPX) and glyoxalase I genes in tobacco BY-2 cells exposed to salt stress.…”