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標題: | 綠豆幼苗下胚軸不定根發生機制的研究 Studies on the formation of adventitious root initial in mung bean seedling hypocotyl |
作者: | Lisa Lee 李麗莎 |
出版年 : | 1977 |
學位: | 碩士 |
摘要: | 生長至第七天的綠豆幼苗切株,浸置蒸餾水中,四天後,在下胚軸基部會出現四行十字排列的不定根。若將切株浸置在NAA溶液,於不同時間再移入蒸餾水中,不定根仍與對照組同時長出,但NAA會促進不定根的數目,其中以處理24小時之切株,不定根數目增加最多。若將切株以四種生長激素:NAA、IBA、2,4-D和以IAA的最適濃度處理24小時後移入蒸餾水中,發現NAA的促進作用最大,可增加三倍以上的不定根數目,蛋白質或核糖核酸合成抑制劑,對不定根的影響為:cyoloheximide會抑制切株的生長,並使植物爛死;α-amanitin不會抑制不定根的生長;而5-FU會完全抑制不定根的發生,並使植物漸漸枯萎。 切株下胚軸基部相對於子葉和第一對小葉維管束跡的?皮部薄壁細胞,是不定根的起源。這些薄壁細胞於切株後36小時開始分裂,48小時形成根原,96小時突破表皮形成不定根。此不定根發生過程,NAA處理者與對照組投有顯著差異,僅36小時者有較顯著的細胞分裂現象。5-FU會抑制細胞分裂。若在細胞開始分裂之後,才將切株移置5-FU中,仍會抑制不定根的形成。 若將切株浸置蒸餾水或NAA溶液24小時後,切取下胚軸,以合有1μCi/ml:H-uridine的培養液培養2小時,發現NAA可促進2倍的核糖核酸合成量。若先用抑制劑preincubation2小時,得知,α-amanitin不會抑制核糖核酸的合成量,5-FU會抑制約60%的核糖核酸合成量。 推測,不定根發生以前,必需有RNA的台成。並且在不定根生長過程中,必需不斷地有rRNA的合成,促使細胞不斷地分裂,以產生根原,形成不定根。 The formation of adventitious roots was studied using 7-day-old mung bean hypocotyl cuttings. The cuttings were presoaked in auxins for different periods followed by transfer into distilled water for 3 days. The cuttings presodked for 24 hrs in NAA at a concentration of 1×10^(-4)M produced more adventitious roots than at any other concentration of used and more than in any other auxin tested. The basal part of the cuttings formed the roots in four rows; these originated from the phloem parenchyma cells. Cell division of those parenchyma cells was evident after 36 hrs of incubation in distilled water. The formation of adventitious roots was irhibited by cycloheximide (5μg/ml). and 5-fluorouracil (1×10^(-3)M) but not by α-amanitin (1μg/ml). Presence of 5-FU in the beginning of the incubation period in distilled water following 24 hrs presoaking, inhibited the cell division and consequently inhibited the formation of root initials. 5-FU also inhibited the formation of adventitious roots even after coil divisions had occurred. Using 8^Huridine as a tracer, RNA synthesis was measured before any cell division had occurred in the root initials. NAA stimulated the RNA synthesis nearly 2 fold and this was inhibited by 5-FU. It is concluded that rRNA synthesis is essential before cell division can occur in the formation of root initials. The ultimate formation of adventitious roots from root initials also requires continuous coil division and also continuous synthesis of rRNA. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/76012 |
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顯示於系所單位: | 植物科學研究所 |
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