受熱與ABA調控水稻基因-OsRZFP1之生理功能分析; Physiological function assay of a heat- and abscisic acid-regulated gene, OsRZFP1

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Title:	受熱與ABA調控水稻基因-OsRZFP1之生理功能分析;Physiological function assay of a heat- and abscisic acid-regulated gene, OsRZFP1
Authors:	徐國軒;Kuo-hsuan Hsu
Contributors:	生命科學研究所
Keywords:	水稻;熱逆境;離層酸;環境逆境;RING鋅指蛋白質;RING zinc finger protein;environmental stresses;rice;heat stress;abscisic acid
Date:	2010-01-22
Issue Date:	2010-06-11 16:08:32 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	水稻是全球主要的糧食作物之一，供應一半以上的人口食用。但隨著近年來全球人口激增與氣候變遷等各種不利因素影響，導致稻米產量逐漸不足，其中環境逆境更是影響糧食作物生長與收成的主要因素。高溫逆境主要影響水稻產量，研究顯示環境溫度高於最適生長溫度1℃稻米產量將減少10%。植物荷爾蒙ABA不僅調控種子成熟，其亦與逆境反應有關，可在遭遇低溫、缺水、高鹽等逆境時大量合成。為提升水稻逆境抗性與維持逆境環境下稻米的產量與品質，我們由oligo microarray結果鑑定出水稻葉片中受高溫與ABA共同調控的基因- OsRZFP1 (cDNA編號AK068005)。胺基酸序列分析發現OsRZFP1在N端具有一CHY鋅指結構，C端則有另一RING-H2鋅指結構。利用反轉錄酶連鎖反應 (reverse transcripts polymerase chain reaction, RT-PCR) 分析OsRZFP1在水稻中的組織特異性及表現情形，發現OsRZFP1主要表現於水稻地上部，在幼苗時期受高溫與ABA誘導後表現量分別提升三倍和兩倍。鋅指蛋白質常被認為執行轉錄因子的功能，但OsRZFP1-GFP結合蛋白質在阿拉伯芥質體細胞和洋蔥表皮細胞中卻表現在細胞核與細胞質當中。為研究OsRZFP1在高溫與ABA逆境抗性中所扮演的角色，我們將OsRZFP1全長及部分互補序列轉殖到水稻及阿拉伯芥中，使OsRZFP1過量或抑制表現；結果發現過量表現OsRZFP1的轉殖水稻可提升高溫與低溫抗性，相反地抑制OsRZFP1表現則使轉殖株對高溫與低溫逆境更加敏感。此外也發現過量表現OsRZFP1的阿拉伯芥轉殖株氣孔關閉比例提高，另亦發現其具低溫及高鹽逆境的抵抗能力。總結來說，這些結果指出OsRZFP1的確作用在高溫與ABA逆境反應之中，同時提供了一個藉由基因改良提升糧食作物逆境抵抗能力的方法。 Rice is one of the important crops supplying food for more than half of the global population. However, yield of rice is not enough because of climatic changes and more and more population on the world recently. Environmental stresses are also a major source of problems for crop growth. High temperature is a major environmental stress affecting yield of crop. Grain yield declined by 10% for each 1℃ increase in the most suitable temperature for rice. Abscisic acid (ABA), a phytohormone, functions in seed maturation and accumulates in response to chilling, drought, and salt stresses. To improve stresses tolerance and preserve yield of rice, we identified a both heat- and ABA-responsive gene, OsRZFP1 (cDNA accession number is AK068005), from oligo microarray expression profiling of rice leaves. The deduced amino acid sequence of OsRZFP1 contains an N-terminal Pfam:zf-CHY domain and a C-terminal RING-H2 zinc finger signature. Using reverse transcripts polymerase chain reaction (RT-PCR) to analyze tissue specificity and expression pattern of OsRZFP1, we found that OsRZFP1 specifically expressed in rice shoot but not in root. Furthermore, the results also indicated that OsRZFP1 showed three-fold heat- and two-fold ABA-inducibility in rice seedling, separately. Although zinc finger protein is usually characterized as transcription factor, subcellular localization of OsRZFP1-GFP in Arabidopsis protoplasts and onion epidermal cells showed OsRZFP1 localized not only in the nucleus but cytoplasm. To study the role of OsRZFP1 for resistance to heat and ABA stresses, we transformed sense strands and antisense fragments of OsRZFP1 into rice and Arabidopsis to overexpress and knock down the transcripts. Temperature tolerance was increased in rice overexpression OsRZFP1 and decreased in OsRZFP1 knock down plants. Moreover, gain of OsRZFP1 function increased not only stomatal closure rate but cold and salt tolerance in transgenic Arabidopsis. Collectively, these results indicated that OsRZFP1 functions in both heat and ABA stresses response. It may provide a genetic engineering approach for improving stresses tolerance in crops.
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