Characterization of a Leaf-type Catalase in Sweet Potato(Ipomoea Batatas Lam. (L.))

定性分析一個甘藷葉型的過氧化氫酶

陳顯榮(Hsien-Jung Chen) ； Mufidah Afiyanti ； 黃冠中(Guan-Jhong Huang) ； 黃世勳(Shyh-Shyun Huang) ； 林耀輝(Yaw-Huei Lin)

《Botanical Studies》 52卷4期 (2011/10) Pp. 417-426

摘要

本研究利用SDS-PAGE膠體活性染色方法從甘藷完全展開的成熟葉片中辨識出一個分子量接近72kDa的主要過氧化氫酶。其活性於PH8-12間較PH小於8時為高，且受β-mercaptoethanol 及3-amino-1,2,4-triazole所抑制。然而其活性於5-45°C間受溫度的影響較小。組織專一性表現顯示其活性主要於葉中被偵測到，且活性由未完全成熟的L2發育階段葉片開始增加，至完全展開成熟的L3 發育階段葉片時具有最高的活性，然後於部份黃化的L4發育階段的老化葉片梢微減少，至完全黃化的L5發育階段的老化葉片幾乎偵測不到，類似於未展開未完全成熟的L1發育階段葉片一樣具有最低的活性。葉片中過氧化氫酶的活性與H2O2含量適成反比關聯性。黑暗及ethephon ( 釋放乙烯的化合物) 處理6 至24小時亦會誘導增加此過氧化氫酶的活性，於處理24至48小時後此過氧化氫酶的活性又漸漸減少；處理葉片中過氧化氫酶的活性亦與H2O2含量適成反比關聯性。依據這些實驗數據我們結論甘藷葉片具有一個主要的過氧化氫酶，其活性於成熟葉片時為最高，於自然及誘導的老化葉片則顯著下降，此過氧化氫酶的活性與葉片清除活化氧族H2O2可能有關。

關鍵字

3-胺基-1,2,4-三氮唑 ； 過氧化氫酶 ； Ethephon ； 葉片老化 ； 甘藷

並列摘要

In this report a major sweet potato catalase was detected and identified from fully-expandedmature leaves using an in-gel activity staining assay with native- and SDS-PAGEs. The catalase activity was optimal from pH 8 to 12, and was repressed by β-mercaptoethanol and a catalase inhibitor 3-amino-1,2,4-triazole. However, catalase activity was much less affected by temperature within the range of 5 to 45°C. Temporal and spatial expression demonstrated that it was specifically detected in leaves, but not in roots and stems. Its activity increased from the immature L2 leaves, reached the maximum in the fully-expanded mature L3 leaves, slightly decreased in the partly-yellowing senescent L4 leaves, and was almost undetectable in the completely yellow L5 leaves, which were similar to the folded and unopened immature L1 leaves. The catalase levels approximately inversely correlated with the H2O2 amounts in leaves of different developmental stages. Dark and ethephon, an ethylene-releasing compound, also enhanced catalase activities from 6 h to 24 h; however, the enhanced activity decreased from 24 h to 48 h in detached leaves after treatment. The catalase levels also approximately inversely correlated with the H2O2 amounts in treated leaves. These data suggest a possible role for sweet potato catalase in coping with H2O2 scavenging in leaves. Based on these data we conclude that a major leaf-type catalase is identified in sweet potato leaves. Its activity level is maximal in mature leaves and becomes significantly lower in natural and in induced senescent leaves. The leaf-type sweet potato catalase likely functions in H2O2 removal in leaves.

並列關鍵字

3-Amino-1,2,4-triazole ； Catalase ； Ethephon ； Leaf senescence ； Sweet potato