國立臺灣大學農藝學系暨研究所王淑珍2006-07-262018-07-112006-07-262018-07-112004-07-31http://ntur.lib.ntu.edu.tw//handle/246246/19845在甘藷葉部組織中，澱粉結合性澱粉合成酵素基因(granule-bound starch synthase I; GBSSI)受到生物時鐘的調控，而使其表現呈現槪日韻律現象。且藉由 nuclear run-on transcriptional assay 證明此調控主要是藉由控制GBSSI 基因之啟動 子轉錄作用之速率。為進一步的探討GBSSI 基因的受生物時鐘調控之分子機制 機制，利用GenomeWalker PCR 之方法篩選出GBSSI 之啟動子，並對GBSSI 基 因的啟動子進行序列特性分析，經由序列比對，發現GBSSI 啟動子序列含有四 個circadian clock-associated 1 protein-binding sites (AATCT)、兩個putative circadian regulation elements (CAANNNNATC) 及六段與光線調控相關的 I-box 。利用轉殖阿拉伯芥進行不同長度之甘藷GBSSI 啟動子功能及活性測試， 結果顯示即使將啟動子縮短至690 bp，其仍受生物時鐘調控。另一方面，以阿拉 伯芥為材料，發現大部分參與澱粉生合成之基因（如soluble starch synthase, ADP-glucose pyrophosphorylase）的表現均呈現概日韻律，因而推論植物內在生 物時鐘在調控暫存性澱粉生合成之過程中，擔任協調基因表現之功能。A starch granule-bound starch synthase I (GBSSI) gene is regulated by a circadian clock in sweet potato leaves. In order to examine whether the promoter region is responsible for controlling a circadian expression of the GBSSI gene, the sweet potato GBSSI promoter was isolated and deleted to different lengths for functional analysis with a GUS reporter gene in transgenic Arabidopsis plants. Nuclear run-on transcriptional assays showed that the circadian control was regulated at the transcriptional rate level, and de novo synthesized proteins were necessary for controlling the rhythm. Promoter assays showed that the GBSSI promoter fragments containing six I-boxes, two putative circadian regulation elements (CAANNNNATC) and four circadian clock-associated 1 protein-binding sites (AATCT) maintained the activity to induce the circadian expression of the GUS gene. Similar to the GBSSI in sweet potato, GBSSI, soluble starch synthase and ADP-glucose pyrophosphorylase genes in Arabidopsis leaves also exhibited a circadian rhythm. These results suggested that common signals may exist in dicotyledonous plants to coordinate the circadian expression of genes involved in the transitory starch synthetic pathway.application/pdf929728 bytesapplication/pdfzh-TW國立臺灣大學農藝學系暨研究所生物時鐘澱粉結合性澱粉合成酵素甘藷澱粉Circadian clockGranule-bound starch synthaseIpomoea batatasStarchreporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/19845/1/922313B002100.pdf