Abscisic Acid Is an Inducer of Hydrogen Peroxide Production in Leaves of Rice Seedlings Grown under Potassium Deficiency

水稻葉苗葉片在缺鉀狀況下所形成之過氧化氫是由脫落酸所誘導

劉純馨(Chun-Hsin Liu) ； 趙雲洋(Yun-Yang Chao) ； 高景輝(Ching-Huei Kao)

《Botanical Studies》 53卷2期 (2012/04) Pp. 229-237

摘要

鉀為植物生長之必要元素。植物在缺鉀狀況下可形成活化氧族（包括過氧化氫）。證據顯示脫落酸之作用機制與過氧化氫的形成有關。本研究主要是探討水稻幼苗生長在缺鉀的狀況下，葉片內所形成之過氧化氫是否與脫落酸之形成有關。水稻幼苗葉片之過氧化氫係利用組織化學與化學分析法測定。缺鉀確定會造成水稻幼苗葉片過氧化氫之累積。NADPH oxidase之抑制劑diphenyleneiodonium chloride與imidazole可降低缺鉀所造成之過氧化氫累積。脫落酸含量則以OsRab16A基因表現以及免疫法來檢測。缺鉀狀況下亦可造成水稻幼苗葉片脫落酸含量之增加。然而，缺鉀狀況下水稻幼苗葉片內脫落酸之累積不是由過氧化氫所誘導。脫落酸合成抑制劑鎢酸鈉能有效降低缺鉀所引起之脫落酸含量增加，以及過氧化氫之累積。該結果似乎說明缺鉀所形成的過氧化氫是經由脫落酸所誘導。正常狀況下生長之水稻幼苗經由外加脫落酸處理，可增加葉片內過氧化氫含量。此結果更支持脫落酸可誘導水稻缺鉀葉片過氧化氫形成之結論。

關鍵字

脫落酸 ； 過氧化氫 ； 缺鉀 ； 水稻

並列摘要

Potassium (K) is essential for many physiological processes. K deficiency is known to increase the production of reactive oxygen species including H2O2 in bean and Arabidopsis. Accumulating evidence indicates that the action of abscisic acid (ABA) is associated with H2O2 production. In this study, we examined the possible involvement of ABA in K deficiency-induced H2O2 production in the leaves of rice seedlings. The histochemical and colorimetrical methods were used to determine H2O2 production in the leaves of rice seedlings. It was observed that K deficiency resulted in an increase in H2O2 content in the leaves. H2O2 production in rice leaves induced by K deficiency was blocked by diphenyleneiodonium chloride and imidazole, NADPH oxidase inhibitors. In this study, ABA content was judged by the expression of OsRab16A (an ABA responsive gene) or was determined by the enzyme-linked immunosorbent assay. K deficiency also resulted in an increase in ABA content in rice leaves. However, ABA accumulation in the leaves under K deficiency is not induced by H2O2. Tungstate (Tu), an ABA biosynthesis inhibitor, was effective in reducing K deficiency-increased ABA content, as well as K deficiency-induced H2O2 production, indicating that K deficiency-induced H2O2 in rice leaves is mediated through ABA. This conclusion is supported further by the observation that exogenous ABA treatment increased H2O2 content in the leaves of rice seedlings grown under K-sufficient conditions.

並列關鍵字

Abscisic acid ； Hydrogen peroxide ； Potassium deficiency ； Oryza sativa L.