The Importance of Glutathione in Defence against Cadmium-induced Toxicity of Rice Seedlings

穀胱甘肽可提高水稻鎘逆境之耐受性

趙雲洋(Yun-Yang Chao) ； 洪傳揚(Chwan-Yang Hong) ； 陳炤曄(Chao-Yeh Chen) ； 高景輝(Ching Huei Kao)

《作物、環境與生物資訊》 8卷4期 (2011/12) Pp. 217-228

https://doi.org/10.30061/CEB.201112.0002

摘要

本研究係以葉綠素含量降低及丙二醛含量增加為鎘毒害之指標，來探討還原態穀胱甘肽（GSH）在水稻幼苗鎘毒害上所扮演之角色。使用品種為對鎘耐受性高之臺農67號（TNG67）與對鎘敏感之臺中在來1號（TN1）。TN1幼苗處理5μM氯化鎘6d後，GSH含量下降，而TNG67則不受影響。氯化鎘處理TN1幼苗過程中，GSH含量先降低然後再降低葉綠素含量。TN1幼苗前處理GSH6小時後，不僅增加GSH及ascorbate（AsA）含量，亦提高ascorbate peroxidase（APX）及glutathione reductase（GR）活性。TN1幼苗前處理GSH後可增加後續處理鎘的耐性。另一方面，TNG67若先處理GSH合成抑制劑buthionine sulfoximine（BSO）不僅降低GSH及AsA含量與APX及GR活性外，亦降低後續處理鎘的耐受性。 外加GSH時可恢復TNG67因BSO降低的GSH及AsA含量與GR及APX活性。綜合上述結果，GSH在水稻鎘逆境中扮演重要的調控角色。

關鍵字

鎘 ； 穀胱甘肽 ； 水稻 ； 氧化逆境

並列摘要

Cadmium (Cd)-sensitive and -tolerant rice cultivars were used to study the role of reduced glutathione (GSH) in Cd-induced toxicity. Cd toxicity of rice seedlings was evaluated by the decrease in chlorophyll content and the increase in malondialehyde content in the second leaves. On treatment with 5 μM CdCl2 for 6 days, the content of GSH decreased in the second leaves of Cd-sensitive cultivar (cv. Taichung Native 1; TN1) but not in the Cd-tolerant cultivar (cv. Tainung 67; TNG67). Moreover, Cd-reduced GSH content was prior to Cd-decreased chlorophyll content in the second leaves of TN1 seedlings. Pretreatment of TN1 seedlings with 1 mM GSH for 6 h resulted in an increase in the contents of GSH and ascorbate (AsA) and the activities of ascorbate peroxidase (APX) and glutathione reductase (GR) in the second leaves of TN1 seedlings. Rice seedlings of TN1 pretreated with GSH were observed to reduce the subsequent Cd-induced toxicity. Exogenous application of the buthionine sulfoximine (BSO), a specific inhibitor of GSH biosynthesis, reduced the contents of GSH and AsA, the activities of GR and APX, and decreased Cd tolerance of TNG67 seedlings. BSO effects on the contents of GSH and AsA, the activities of GR and APX, and Cd toxicity were reversed by the application of GSH. Based on the data obtained in this study, it could be concluded that GSH content plays a role in regulating Cd toxicity of rice seedlings.

並列關鍵字

Cadmium ； Glutathione ； Oryza sativa L. ； Oxidative stress