Proline and glycinebetaine induce antioxidant defense gene expression and suppress cell death in cultured tobacco cells under salt stress

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

“…Plants possess antioxidant defense and glyoxalase systems to protect their cells against the damaging effects of H 2 O 2 , O 2 À , and MG. 13,19,22,23) Proline, besides functioning as an osmoprotectant, suppresses production of free radicals 1,6,11) and reactive oxygen species (ROS). 24,25) Our recent study indicated that both exogenous proline and betaine decrease H 2 O 2 accumulation induced by NaCl 12) and cadmium. 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.…”

“…[4][5][6][7] Moreover, proline and betaine provide protection against stress by maintaining redox homeostasis. 8) Under salt stress, exogenous application of proline or betaine upregulates stressprotective proteins, 9) and reduces lipid peroxidation [10][11][12] and protein oxidation. 8) Environmental stress, including salinity, induces the production of hydrogen peroxide (H 2 O 2 ), the superoxide radical (O 2 À ), and nitric oxide (NO) in plant cells.…”

“…8) Environmental stress, including salinity, induces the production of hydrogen peroxide (H 2 O 2 ), the superoxide radical (O 2 À ), and nitric oxide (NO) in plant cells. 1,[12][13][14][15][16][17][18] Excess production of H 2 O 2 , O 2 À , and NO is toxic to plants, and causes oxidative damage to cellular constituents, leading to cell death. [12][13][14][18][19][20] In plant cells, salinity also leads to the accumulation of methylglyoxal (MG), a cytotoxic compound that can react with and modify other molecules, including DNA and proteins.…”

“…1,[12][13][14][15][16][17][18] Excess production of H 2 O 2 , O 2 À , and NO is toxic to plants, and causes oxidative damage to cellular constituents, leading to cell death. [12][13][14][18][19][20] In plant cells, salinity also leads to the accumulation of methylglyoxal (MG), a cytotoxic compound that can react with and modify other molecules, including DNA and proteins. [21][22][23] Because of the highly cytotoxic and reactive properties of H 2 O 2 , O 2 À , NO, and MG, their concentrations must be kept under strict control.…”

“…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.…”