環境逆境常會誘導植物基因大量表現，這些基因可能是訊息傳導或是抵抗機制的酵素或是逆境反應的基因等，以使植物產生各種可能的抵抗機制而存活。本實驗以北點墨法發現一個會受到硫酸銅所誘導的基因tryptophan synthase β-chain 1 (TSB1)，位於色氨酸(tryptophan)合成路徑，負責將絲氨酸(serine)和吲哚(indole)合成色氨酸之步驟。經由農桿菌轉殖技術將TSB1基因大量表現於阿拉伯芥，來瞭解這個受銅誘導表現的基因功能，並觀察TSB1轉殖株與逆境的耐受性之關係。在TSB1轉殖株與未轉殖之wild type的逆境分析中發現，轉殖株對於硫酸銅(CuSO4)、氯化鎘(CdCl2)、氯化鈉(NaCl)及paraquat之耐受性高於未轉殖的wild type。並發現一位於色氨酸衍生物的代謝路徑下游的基因aldehye dehydrogenase 3 (ALDH3)在轉殖植物中RNA的表現量大於未轉殖的wild type。根據文獻參考，推測TSB1轉殖株的逆境耐受性的增加可能與ALDH3基因參與的代謝途徑相關。為瞭解之間的相關性，利用GC/MS分析TSB1轉殖株與未轉殖的wild type色胺酸含量及其代謝途徑中的衍生物。結果顯示在轉殖植物中除色氨酸含量增加外，ALDH3的產物5-hydroxyindole acetoaldehyde (HIAA)含量也有增加。上述這些結果建議TSB1轉殖株對逆境耐受性的增加有可能是受到ALDH3這個基因表現量增加，進而影響TSB1轉殖株對逆境的耐受性。 Environmental stresses activate plant genes expression that may act as signal or defense enzymes and/or responsive genes to enhance plant to tolerant or resistant to various stresses. A gene, tryptophan synthase β-chain 1(TSB1) induced by 100 μM CuSO4 is responsible for the final step of tryptophan synthesis pathway; TSB1 converts the indole and serine to tryptophan. To study the function of TSB1, we create a TSB1 over- expressed transgenic Arabidopsis by Agrobacterium tumefaciens. TSB1 transgenic plants were tolerance to copper, cadmium, salinity and paraquat comparing to wild type plant. The mRNA transcripts of aldehye dehydrogenase 3 (ALDH3), one synthesis enzyme in the down streaming of tryptophan-derived metabolism pathway, were increased in TSB1 transgenic plants than wild-type plants. The results imply that the metabolism pathway of ALDH3 may be contributed to the tolerance to various stresses in TSB1 transgenic plants. The results of GC/MS analysis show that the concentrations of tryptophan and HIAA which is the product of the ALDH3 enzyme, are higher than those of wild type. These results suggest that increased expression of ALDH3 in TSB1 transgenic plant may increase tolerance to stresses.
