喜樹鹼(camptothecin, CPT)是一種單萜類吲哚生物鹼，文獻指出在青脆枝根部樹皮具有最高含量的喜樹鹼，但青脆枝中喜樹鹼的生合成卻仍未被完全解析，故本研究從青跪枝當中選殖4個喜樹驗生合成相關基因，anthranilate synthase (NnASA)、cytochrome P450 reductase (NnCPR)、tryptophan decarboxylase (NnTDC)、secologanin synthase (NnSLS)並利用離葉系統進行不同的處理。研究結果指出，當以25°C以上的高溫處理，皆可使4個喜樹鹼生合成基因表現量提高；當施加200μM甲基茉莉酸處理，NnASA、NnCPR及NnTDC基因表現量會受到誘導，但NnSLS則不受其誘導；而高濃度的氣化鈉溶液處理則會抑制NnASA、NnTDC及NnCPR基因的表現，亦會造成青脆枝喜樹鹼的累積銳減；本研究結果可提供青脆枝生產喜樹驗的最適生長條件。

Camptothecin (CPT), a monoterpene indole alkaloid, is an important anticancer compound. Current reports revealed that the highest level of CPT was detected in root bark of N. nimmoniana, but the CPT biosynthesis in N. nimmoniana is still unclear. In this study, four CPT biosynthetic related genes, including anthranilate synthase (NnASA), cytochrome P450 reductase (NnCPR), tryptophan decarboxylase (NnTDC) and secologanin synthase (NnSLS) were cloned from N. nimmoniana. The expression profiling of CPT-biosynthetic genes was monitored under several treatments for disclosing the pivotal regulatory network. Results found that under the warmer ambient temperature condition (>25° C), it can induce all the four CPT-biosynthetic genes .Except for NnSLS, NnASA、NnCPR and NnTDC were induced by 200μM methyl jasmonate, but reduced by high concentration of sodium chloride. Our results revealed the CPT-biosynthesis through genetic and molecular network, which can provide reference for optimal cultivating of N. nimmoniana.