水稻鎘逆境生理之研究：Glutathione、Ascorbic acid 與水楊酸之作用

Studies on the physiology of cadmium stress in rice seedlings:The role of glutathione, ascorbic acid and salicylic acid

陳炤曄(Chao-Yeh Chen)

指導教授 ： 高景輝

國立臺灣大學/生物資源暨農學院/農藝學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.00057

摘要

本論文係利用台中在來一號（Oryza sativa L. cv. Taichung Native 1, TN1）與台農六十七號（cv. Tainung 67, TNG67）。探討TNG67與TN1水稻幼苗對鎘耐受性與reduced glutathione （GSH）和ascorbic acid （AsA）之關係。此外，本論文也利用台中在來一號切離葉片為材料，探討水稻切離葉片經水楊酸（salicylic acid）處理對後續鎘毒害之影響。
本論文以葉片外觀、葉綠素含量以及malondialdehyde（MDA）含量作為鎘毒害之指標。在氯化鎘處理下，TN1幼苗第二片葉片外觀變黃、葉綠素含量下降及MDA含量增加，而在TNG67水稻幼苗葉片上並未出現毒害現象。這樣的差異可能來自於兩品種GSH與AsA參與調控水稻幼苗對鎘之耐性。支持的證據為：（一）氯化鎘處理會造成TN1幼苗葉片GSH和AsA含量下降，但不影響TNG67幼苗葉片的GSH與AsA含量。（二）TN1幼苗經外加GSH和AsA處理，或以合成AsA之前驅物L-galactono-1,4-lactone處理，可以克服後續的氯化鎘毒害（三）利用GSH合成抑制劑buthionine sulfoximine （BSO）處理TNG67幼苗，會降低TNG67葉片內GSH含量，同時降低TNG67幼苗對氯化鎘的耐受性。
水楊酸處理TN1水稻切離葉片後，H2O2會有累積的現象。NADPH oxidase所催化之反應可形成H2O2。以NADPH oxidase抑制劑diphenyleneiodonium chloride（DPI）和imidazole（IMD）處理水稻切離葉片，可降低水楊酸所促進之H2O2累積。水楊酸處理可增加diamine oxidase（DAO）之活性。這些結果說明水楊酸處理水稻切離葉片所促進H2O2之生成，與NADPH odidase和DAO有關。水楊酸處理TN1水稻切離葉片，可增加抗氧化酵素superoxide dismutase（SOD）、glutathione reductase（GR）、ascorbate peroxidase（APX）與catalase（CAT）活性，增加抗氧化物GSH含量，但降低抗氧化物AsA含量。水楊酸前處理TN1水稻切離葉片，可降低後續巴拉刈與鎘處理造成之傷害。

關鍵字

水稻 ； 鎘 ； glutathione ； ascorbic acid ； 水楊酸

並列摘要

In this thesis, two rice (Oryza sativa L.) cultivars (cv. Taichung Native 1 and cv. Tainung 67, TNG67) were used to study the regulatory role of glutathione (GSH) and ascorbic acid (AsA) in Cd induced toxicity. Also included in this thesis is the protective effect of salicylic acid (SA) against Cd toxicity of detached leaves of TN1 seedlings.
Cd toxicity was judged by leaf chlorosis, the decrease in chlorophyll content and the increase in malondialdehyde (MDA) content. The results indicated that TNG67 rice seedlings are Cd tolerance and TN1 rice seedlings are Cd-sensitive. The different Cd sensitivities between those two cultivars seem to be regulated by GSH and AsA. This conclusion was based on the observations that (a) CdCl2 treatment resulted in a decrease in GSH and AsA contents of the leaves of TN1 seedlings, but not in those of TNG67 seedlings; (b) exogenous application of GSH, AsA and L-galactono- 1,4-lactone (a precursor of AsA) could decrease the subsequent Cd toxicity in TN1 seedlings; (c) buthionine sulphoximine ( an inhibitor of GSH synthesis, BSO) treatment reduced GSH content as well as Cd tolerance of TNG67 seedlings.
Detached TN1 rice leaves pretreated with SA (3 mM) resulted in an increase in H2O2 content. Diphenyleneiodonium chloride (DPI) and imidazloe (IMD), both are NADPH oxidase inhibitor, inhibit SA-induced accumulation of H2O2. SA pretreatment also resulted in an increase in diamine oxidase (DAO) activity. These results suggest that NADPH oxidase and DAO are H2O2-generating enzymes in SA-pretreated detached leaves. On treatment with SA, the antioxidant enzymes activities (SOD, CAT, GR, APX) and GSH contents increased, but AsA contents decreased in detached leaves. Evidence was provided to show that SA protects detached rice leaves against paraquat and Cd toxicities.

並列關鍵字

rice ； cadmium ； glutathione ； ascorbic acid ； salicylic acid

參考文獻

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