銅鎘逆境下菸草根部離層酸及脯胺酸代謝基因之功能研究

Functional studies on abscisic acid and proline metabolism related genes in Nicotiana benthamiana roots under copper and cadmium stress

范竣皓(Chun-Hao Fan)

指導教授 ： 陳建德

國立臺灣大學/生物資源暨農學院/農業化學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.01762

摘要

本研究目的為瞭解菸草根部於重金屬逆境下之抵抗機制。台灣土壤之重金屬汙染，以銅及鎘佔多數，兩者皆可由土壤被植物吸收。植物面臨此毒害逆境產生之抵抗機制可應用於植生復育。然而目前研究多著重於植物地上部生理狀態與重金屬的累積，較少有對於根部之生理研究，此可能是根部取樣不易，或取樣時間過長。本研究採介質於內與砂耕於外之混和方式，藉以建立易取樣之菸草新根研究平臺，並藉由外加離層酸或離層酸生成抑制劑 (fluridone) 及利用病毒誘導基因沉寂，研究菸草新根於重金屬逆境下離層酸及脯胺酸代謝基因可能扮演的角色。結果顯示，銅處理使菸草新根離層酸含量上升 (80％) 而鎘處理使離層酸含量下降 (30％)，外加離層酸處理，使菸草鎘吸收下降而銅吸收則無異。推測因銅處理本身使離層酸含量上升，因此外加離層酸對銅吸收影響有限。反之，外加fluridone使菸草根離層酸下降，可提高菸草對銅吸收，而鎘之吸收無異。推測因鎘處理本身使根離層酸含量下降，因此外加fluridone對鎘吸收影響有限。上述結果顯示根部離層酸含量之改變影響菸草對重金屬吸收。菸草新根於銅或鎘逆境下皆降低游離脯胺酸含量，鍵結型脯胺酸含量不變。然而利用病毒誘導基因沉寂，抑制脯胺酸代謝基因PDH (proline dehydrogenase) 表現，可增加鎘處理下菸草根部游離脯胺酸含量，據此推測菸草根部可能藉增加PDH基因表現，使脯胺酸於根部含量下降，然而其機制尚待更進一步了解。

關鍵字

病毒誘導基因沉寂 ； 脯胺酸 ； 離層酸 ； 銅 ； 鎘 ； 菸草

並列摘要

The aim of this thesis was to reveal the mechanism of tobacco roots against heavy metals. In Taiwan, many heavy metal contaminated soils contain copper and cadmium, both of them were easily up taken by plants. When plants faced to heavy metals stress, their mechanisms that against the toxicity could be applied in phytoremediation. However, most researches focused on the heavy metal accumulation and the physiological changes in shoot. The reasons of only few reports on root status could be the tissue lost or the time consuming during root collecting. In this study, plants were transplanted with soil and burred in sand, by which the newly growing roots can be collected easily. After that, the treatment of abscisic acid (ABA), fluridone (ABA synthesis inhibitor) or virus induced gene silencing (VIGS) in plant root were applied before heavy metals treatments. The results showed tobacco ABA increased about 80% in new root under copper treatment, but decreased about 30% under cadmium treatment. The addition of ABA in sand culture decreased cadmium uptake, but did not affect copper uptake. On the contrary, the addition of fluridone not only decreased ABA content in new root but also increased copper uptake and not affect cadmium uptake. Both of copper and cadmium decreased new root free form proline, but did not affect conjugated form proline content. Using VIGS to suppress PDH (proline dehydrogenase) gene increase new root proline content under cadmium stress, suggesting that cadmium decreased proline content in tobacco new root could be caused by the increase of PDH gene activity.

並列關鍵字

virus induced gene silencing (VIGS) ； proline ； abscisic acid ； copper ； cadmium ； tobacco

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