Modulation of Antioxidant Defense System and NADPH Oxidase in Pluchea Indica Leaves by Water Deficit Stress

鯽魚膽切離葉於缺水環境下抗氧化防禦系統之調節與 NADPH氧化酶活性之關係

張敏郎(Min-Lang Chang) ； 廖麗貞(Li-Jen Liao) ； 林佳弘(Jia-Hong Lin) ； 劉景煌(Zin-Huang Liu) ； 許媛婷(Yuan-Ting Hsu) ； 李澤民(Tse-Min Lee)

《Botanical Studies》 53卷1期 (2012/01) Pp. 45-54

摘要

本研究探討鯽魚膽（Plucheaindica（L.）Less.）切離葉片於PEG誘導產生的缺水處理中，其抗氧化物質及抗氧化酶活性之變化情形，並利用原生質膜NADPH氧化酶抑制劑DPI（diphenyleneiodonium）處理，了解還原態NADPH氧化酶（NADPHoxidase）所扮演之角色。經PEG缺水處理的鯽魚膽葉片其含水量與TTC活性降低，但malondialdehyde（MDA）、totalperoxide、O2΄-與H2O2量增加，顯示鯽魚膽葉片在缺水逆境確實可誘導氧化逆境的產生。在中度缺水的情況下，totalascorbate（AsA），AsAcontents及AsA/oxidizedAsAratios皆增加，且隨著水勢增加，totalglutathione（GSH）、GSHcontents與GSH/GSSGratios亦增加。而superoxidedismutase（SOD）活性在PEG處理24小時沒有明顯改變，但在48小時後則增加。catalase（CAT）與glutathionereductase（GR）活性隨著水勢降低而增加，而peroxidase（POX）活性則只在水勢-1.2MPa增加，ascorbateperoxidase（APX）活性只在中度缺水時增加。這些藉由缺水逆境所誘導產生之抗氧化物質的累積與抗氧化酶活性之變化情形可被DPI抑制，顯示鯽魚膽在氧化逆境中可啟動其防禦系統中之活性氧族（reactiveoxygenspecies，ROS）訊息分子。因而，鯽魚膽葉片對中度缺水逆境之反應係藉由NADPHoxidase所媒介之非酵素形式或酵素形式之氧化防禦機制來清除ROS而達成。

關鍵字

NADPH 氧化酶 ； 鯽魚膽 ； 活性氧族 ； 缺水逆境 ； 抗氧化防禦系統

並列摘要

We investigated changes in antioxidant content and antioxidant enzyme activity in polyethylene glycol (PEG)-induced water deficit stressed Pluchea indica leaves. We also used diphenylene iodonium (DPI), a plasma membrane NADPH oxidase suicide inhibitor, to examine the role of reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in the induction of antioxidant defense systems. PEG decreased water content and the reduction ability of 2,3,5-triphenyltetrazolium chloride (TTC), but increased malondialdehyde (MDA), total peroxide, O2 - and H2O2 contents, indicating water deficit-dependent oxidative stress. Total ascorbate (AsA), AsA contents, and AsA/oxidized AsA ratios were increased by moderate water deficit (-0.6 MPa) conditions, while total glutathione (GSH), GSH contents and GSH/GSSG ratios increased as water potential decreased. Superoxide dismutase (SOD) activity was not affected after 24 h of PEG treatment but decreased after 48 h. Catalase (CAT) activity increased as water potential decreased while peroxidase (POX) activity increased only at -1.2 MPa. Ascorbate peroxidase (APX) activity increased under moderate water deficit and glutathione reductase (GR) activity increased as water potential decreased. DPI depressed the induction of antioxidant accumulation and antioxidant enzyme activity by water deficit, indicating that reactive oxygen species (ROS) signals are involved in activating defense systems in P. indica in response to oxidative stress. We conclude that moderate water deficit stress induces both NADPH oxidase-mediated non-enzymatic and enzymatic oxidative defense mechanisms in ROS scavenging in P. indica leaves.

並列關鍵字

Antioxidant defense system ； NADPH oxidase ； Pluchea indica ； Reactive oxygen species (ROS) ； Water deficit