• 作者： 高景輝
• 作者服務機構： 國立臺灣大學農藝系
• 中文摘要： 本文主要討論氫離子釋放，細胞質鈣離子濃度，多元胺與水稻葉片老化間的關係。水稻切離葉片脯胺酸累積的機制亦一併討論。水稻切離葉片氫離子釋放的能力隨著黑暗處理時間之增加而降低，此種降低在老化開始之前發生。累積的證據顯示氫離子釋放的能力對水稻切離葉子老化扮演重要的調控角色。利用一些影響鈣離子吸收的藥劑與calmodulin抑制劑研究的結果，明顯的說明細胞質鈣離子的濃度，可能經由calmodulin的機制控制水稻切離葉片老化。黑暗中老化的水稻切離葉片會大量累積脯胺酸。基本上，abscisic acid所誘導的脯胺酸累積機制與弱酸isobutyric acid所誘導脯胺酸累積機制不同。細胞液的酸化並不是脯胺酸累積的唯一因素，可能尚有其他因素參與。 外加多元胺與多元胺氧化產物diaminopropane可有效的延緩水稻切離葉片老化。一些證據顯示水稻葉片內的多元胺含量不可能控制水稻葉片老化。外加多元胺延緩水稻切離葉片的老化不能以多元胺轉變為 diaminopropane或者多元可穩定細胞膜來解釋。最有趣的是，外加多元胺可促進乙烯的形成。因此，多元胺不可能經由乙烯合成的控制而影響水稻葉片老化。
• 英文摘要： The roles of proton secretion activity, the cytosolic level of calcium, and polyamines in regulatingrice leaf senescence are reviewed. The possible mechanism of proline accumulation in detached rice leavesis also discussed. Proton secretion activity of detached rice leaves decreased with an increasing duration ofdark incubation. This decrease preceded the commencement of senescence. Accumulated evidence suggeststhat proton secretion activity of detached rice leaves may play a regulatory role in senescence. The possibleinvolvement of calcium and calmodulin in the regulation of rice leaf senescence was tested by using com-pounds that influenced calcium uptake and calmodulin inhibitors. Results suggest indirectly that cytosoliccalcium may regulate senescence of detached rice leaves through a calmodulin-dependent mechanism. Prolinein detached rice leaves was shown to accumulate during dark-induced senescence. It was found that themode of action of abscisic acid in inducing the accumulation of proline in detached rice leaves differs fromthat of permeable weak acid, isobutyric acid. Our results also indicate that factors other than acidificationof the cell sap are involved in regulation of the accumulation of proline in detached rice leaves. Exogenous polyamines and diaminopropane, an oxidation product of polyamines, are effective in re-tarding rice leaf senescence. Several lines of evidence indicate that endogenous polyamine levels do not seemto be the part of the chain of events leading to the initiation of rice leaf senescence. Neither the possiblerequirement for conversion of polyamines to diaminopropane nor the possibility that polyamines stabilizecell membranes can explain the mechanism in which exogenous polyamines retard senescence of detached riceleaves. Of particular interest is the finding that polyamines effectively promote the production of ethylenein detached rice leaves under both light and dark conditions. Thus, the mechanism in which polyaminesretard rice leaf senescence is unlikely to be mediated through the inhibition of ethylene production.
• 中文關鍵字： proton secretion; calcium; polyamines; rice; leaf senescence.
• 英文關鍵字： --