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標題: | Hydrogen Peroxide與Nitric Oxide對於甘藷防禦機制之功能探討 Functional analysis of hydrogen peroxide and nitric oxide in the defense response of sweet potato |
作者: | Pei-Ju Jih 紀姵如 |
出版年 : | 2003 |
學位: | 碩士 |
摘要: | 當植物受到外來生物性逆境,如病原菌感染、物理性傷害等,體內會產生許多蛋白質以抵禦這逆境的入侵與擴大,此過程稱為植物防禦機制。植物防禦機制的啟動是受到一連串嚴密的訊息分子來調控,這些訊息分子包含了細胞壁被破壞時所釋放出的多醣類、植物荷爾蒙茉莉酸(methyl jasmonate, MeJA)與活性氧類(reactive oxygen species, ROS)。 ROS包含了hydrogen peroxide (H2O2)、superoxide(O2-)。適量的ROS是擔任訊息分子很好的角色,但過量的ROS反而會破壞細胞膜並導致細胞死亡,所以其中必有一嚴謹的機制來調控ROS在細胞中的含量。 Nitric oxide(NO)近年來被發現參與許多植物生長發育的過程,也發現植物遭受病原菌入侵時會有大量的NO產生。部分學者認為NO可能會引起大量ROS產生,進一步導致細胞死亡,部份學者則推論在植物防禦機制上NO可能會降低ROS的含量,而擔任一保護者的角色,確切的功能與作用機制目前仍不清楚。 本實驗利用甘藷為實驗材料,藉由傷害誘導基因ipomoelin(IPO)作為分子標記(molecular marker),以外加的方式供給植物NO或H2O2,藉由IPO基因的表現情形來探討NO與H2O2在植物防禦機制中所扮演的角色。同時藉由偵測H2O2和NO影像的染劑來觀察植物在葉片受傷後兩者的表現情形與相互作用。在以上實驗結果分析均指出,NO會降低植物體本身因傷害而產生H2O2之含量,推論在植物防禦機制上扮演一保護者的角色。 另一方面,因希望對NO的作用機制能有進一步的瞭解,在此藉由蛋白質二維電泳的方式找尋出受NO所誘導而表現的蛋白質,經由蛋白質定序後得到六種蛋白質序列,分別為:thylakoid lumenal protein, SUMO protein, nucleoside diphosphate kinase (NDPK), sporamin B precursor,與兩種CuZnSOD 。同時經由SOD與catalase活性染的方式發現,NO處理後的葉片會引起SOD與catalase的大量表現。綜合以上結果明確指出在植物防禦機制上,NO會藉由降低因傷害產生的H2O2之含量,避免植物體本身因過多的ROS而造成的傷害。 Plants respond to insect attack and mechanical wounding by activating the expression of defense genes. This process involves a series of signal transduction factors which include methyl jasmonat (MeJA) and reactive oxygen species (ROS), such as hydrogen peroxide (H2O2) and superoxide (O2-). When ROS are generated at a controlled level, cell can use them as signals to activate defense genes. However, the excess amount of ROS present may damage cells, and hence cells have evolved an antioxidant system involving superoxide dismutase (SOD), catalase, and nitric oxide (NO) to protect cells from ROS destruction. In this study, we used the Ipomoelin (IPO) gene isolated from sweet potato as a molecular marker to investigate the molecular events of NO and H2O2 after sweet potato was mechanically wounded. Results indicate that mechanical wounding can induce leaves to produce H2O2, which further stimulate the expression of the IPO gene. On the contrary, NO delays the expression of the IPO gene by reducing the production of H2O2. Meanwhile, six NO-induced proteins were isolated from two-dimensional electrophoresis, and one of them is SOD as expected. In conclusion, when sweet potato is wounded, both H2O2 and NO are produced to modulate the defense response, which may protect plants from insect and pathogen invasion and at the same time prevent plant from damage caused by ROS. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/75421 |
全文授權: | 未授權 |
顯示於系所單位: | 植物科學研究所 |
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