Studies on NaCl stress of rice seedling roots: the role of hydrogen peroxide
Date Issued
2012
Date
2012
Author(s)
Wei, Mi-Yin
Abstract
In this thesis, rice (Oryza sativa L. cv. Taichung Native 1) etiolated seedlings were used to investigate (a) the role of H2O2 in NaCl-inibited growth of rice etiolated seedling roots, (b) the role of H2O2 in NaCl-increased glutathione reductase(GR)activity of rice etiolated seedling roots, (c) and the role of H2O2 in NaCl-increased heme oxygenase activity of rice etiolated seedling roots.
Rice etiolated seedlings treated with NaCl increased H2O2 production in rice roots (3 hours), and then inhibited root growth of etiolated seedlings (6 hours). Addition of H2O2 scavenger ascorbic acid (AsA) and nitric oxide (NO) donor sodium nitroprusside(SNP) , which decreased H2O2 accumulation, could not reduce NaCl-inhibited growth in rice roots. Also, application of NADPH oxidase inhibitors diphenyleneiodonium(DPI) and imidazole(IMD), which inhibited the H2O2 production, had no effect on NaCl-inhibited root growth. These data indicated that H2O2 production through NADPH oxidase caused by Na+ is unlikely responsible for
NaCl-inhibited root growth.
NaCl treatment increased H2O2 production and GR activity in rice roots. Addition of AsA and SNP, which decreased H2O2 accumulation, could lower the NaCl-induced GR activity. Also, application of DPI and IMD, which inhibited the
H2O2 production, reduced the NaCl-induced GR activity. NaCl treatment resulted in an increase in HO activity in roots of rice etiolated seedlings. Results of time-course study indicated that H2O2 accumulation occurred 3 hours after NaCl treatment, whereas the increase in HO activity occurred 6 hours after NaCl treatment. Addition of AsA and SNP, which decreased H2O2 accumulation, could lower the NaCl-induced
HO activity in rice etiolated seedling roots. Also, application of DPI and IMD reduced the NaCl-induced HO activity. Moreover, NaNO3 and NaCl are equally effective in
inducing GR and HO activity, indicating that Na+ but not Cl- is responsible for increasing GR and HO activities.
Based on the data of this thesis, it is concluded that H2O2 production caused by NaCl may be responsible for NaCl-increased GR and HO activities in rice etiolated seedling roots.
Subjects
Glutathione reductase
growth
H2O2
heme oxygenase
NaCl
rice
seedling roots
Type
thesis
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