Oxidative damage and responses of glutathione and ascorbate in rice (Oryza sativa L.) seedlings subjected salinity stress.

• Main Authors: Cih-Ting Syu, 許慈婷
• Other Authors: 朱德民
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/85920328674866919355

碩士 === 國立中興大學 === 農藝學系所 === 94 === The purpose of this study is to explore oxidative damage levels, the changes of total glutathione and ascorbate (AsA) contents and it’s play roles in rice seedlings subjected salinity stress. In addition, the possibility of decrease oxidative damages of plant and promote salt tolerance by either osmolytes or abscisic acid (ABA) pretreatments under salinity stress. Intact leaves and detached leaves of rice cultivar TNG 67 seedlings at 3-leaf stage were used as materials in this study, the experiment results were summarized as below: Rice seedlings were subjected to NaCl for 3d, chlorophyll content was decreased; enhancement of hydrogen peroxide (H2O2) and malondialhehyde (MDA) contents were accompanied with increasing salt concentration in plants, suggested oxidative damage more serious; the contents of soluble protein had no change, total glutathione content was increased, and AsA content was decreased, particularly in high salt concentration. The contents of soluble protein, chlorophyll, H2O2 and MDA content were no significantly changes in rice detached leaves treated NaCl for 36h, total glutathione content was increased, however content of AsA showed decreasing trend as increasing NaCl concentration. The content of total glutathione and MDA was significantly increased by 240 mM NaCl treatment, especially. The reaction of intact seedling leaves and detached leaves were similar under different concentrations of NaCl, but the reaction levels of detached leaves lower than intact seedling. Reaction of detached leaves was only significant at high NaCl concentration treatment. The contents of H2O2, MDA and total glutathione were increasing, but AsA content was decreasing as gradually increasing NaCl concentration in rice seedling. The results also showed the similar reactions occurance as increasing treating time at the same NaCl concentration. It is evident that adjust osmotic potential in plant with gradually increasing NaCl concentration can’t decrease the damage levels in plant under salinity stress. The rice detached leaves were pretreated with three concentrations of glucose for 12h and then transferred to 180 mM NaCl for 36h. Oxidative damage levels were decreased in detached leaves by medium (0.1 M) glucose pretreatment under salinity stress, due to the content of total glutathione was significantly increased and maintained the content of AsA. Reactions of rice leaves were pretreated with different osmolytes and then transferred to NaCl were not identical completely. Generally, the contents of H2O2 and AsA were decreasing, the content of MDA was no effect and total glutathione content was significantly increasing by all osmolytes pretreatment in salinity stress. The results showed the effect of oxidative damages was decreased by sucrose more than proline, sorbitol and NaCl pretreatment respectively. The detached leaves were pretreated with ABA and ABA biosynthesis inhibitor, tungstate and ABA+ tungstate. The decreased MDA content and increased content of total glutathione were the most in detaced leaves was pretreated with tungstate. Threrfore, effects of oxidative damage were mitigated by tungstate pretreatment under salinity stress was best; effects of ABA and ABA+ tungstate pretreatment were not good. The results of ABA, tungstate and ABA+ tungstate pretreatment were not conformed to our expectation. In other words, it was not have the effect of oxidative damage was mitigated by ABA pretreatment in this experiment. The possible causes were discussed in this paper.