乙烯誘導芥藍葉片老化過程中之抗氧化反應

Antioxidant Responses in Ethylene-Induced Leaf Senescence of Chinese Kale

張嘉滿(Chia-Man Chang)

指導教授 ： 王自存

國立臺灣大學/生物資源暨農學院/園藝學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.01731

摘要

中文摘要
本試驗以對乙烯頗為敏感的葉菜類作物‘蕙津’芥藍 (Brassica oleracea L. Albograbra Group cv. ‘Veg Gin’) 3週苗齡的第二片本葉之切離葉片為試驗材料，研究乙烯促進切離葉片老化時抗氧化酵素之活性的反應，以及乙烯所促進的葉片老化是否與氧化逆境有關。
芥藍幼苗第二片本葉切離後在 25℃ 黑暗中以 1 ppm 乙烯處理 4天中，明顯加速葉片黃化。乙烯處理第3天葉綠素與蛋白質含量顯著低於對照(空氣)組。過氧化氫 (H2O2) 與 malondialdehyde (MDA) 含量在乙烯處理第 1、2 天開始增加並高於對照組。植物抗氧化防禦系統的抗氧化酵素 ascorbate peroxidase (APX)、glutathione reductase (GR) 與peroxidase (POX) 等抗氧化酵素比活性在乙烯處理 2 天後顯著增加，但 superoxide dismutase (SOD) 與 catalase (CAT) 則無顯著變化。此結果表示，乙烯連續處理誘導芥藍切離葉片開始老化，是由於乙烯促使內生 H2O2 含量的增加，造成脂質過氧化作用程度加劇，導致 MDA 含量的累積；在引起葉片氧化逆境增加時，APX、GR 與 POX 等抗氧化酵素比活性也被誘導增加。
在乙烯處理之前先以乙烯作用抑制劑 1-MCP 處理芥藍切離葉片，會完全抑制葉片之老化反應以及由乙烯所造成之各項反應，包括葉綠素蛋白質含量降低，H2O2、MDA 含量增加及 APX、GR、POX 比活性增加等現象。此結果進一步顯示乙烯會使葉片發生氧化逆境而加速葉片老化。在本試驗中，切離葉片的抗氧化酵素比活性雖因氧化逆境發生而增加，但由於持續的乙烯處理仍造成無法抵抗的氧化逆境，葉片最後變黃老化。

關鍵字

乙烯 ； 抗氧化酵素 ； 葉片老化

並列摘要

Summary
This research was studied the effect of ethylene-induced leaf senescence on enzymatic-antioxidant activity responses of detached leaves of 3-week sold of Chinese kale seedling (Brassica oleracea L. Albograbra Group cv. ‘Veg Gin’) - an ethylene-sensitive leafy vegetable crop. The relationship between ethylene-induced leaf senescence and oxidative stress was also studied.
Exogenous application of 1 ppm ethylene for 4 days was found to accelerated the yellowing process of detached leaves of Chinese kale incubated in dark at 25℃. Treatment of leaves with ethylene had lower chlorophyll and protein content than control for 3 days. H2O2 and malondialdehyde (MDA) level stared to increase at the first, second day in the period of ethylene treatment. In the enzymatic-antioxidant defense system, the specific activity of APX, GR and POX were increase，but the specific activity of SOD and CAT were not affected by ethylene. Our results suggest that ethylene-induced leaf senescence was due to the increase level of H2O2 promoted by ethylene, led to the increased level of lipid peroxidation resulted in the accumulation of MDA, thus oxidative stress occurred. At the same time, the specific activity of enzymatic- antioxidant defense system such as APX, GR and POX were induced to increase.
Pretreated with ethylene action inhibitor 1-methylcyclopropene
(1-MCP) was found to retarded the leaf senescence, reduced the decreased the level of chlorophyll and protein level, the increased level of H2O2 and lipid peroxidation level, as well as the increase specific activity of enzymatic- antioxidant defense system such as APX, GR and POX. These results also suggest that oxidative stress in detached leaves of Chinese kale was induced by ethylene treatment. However, the increased level of specific activity of enzymatic- antioxidant defense system could not overcome the oxidative stress induced by ethylene, detached leaves turned yellowed and senescence finally.

並列關鍵字

antioxidant enzyme ； ethylene ； leaf senescence

參考文獻

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