Tissue-specific and Developmental Regulation of Camptothecin and 10-hydroxycamptothecin Levels in Camptotheca acuminate

喜樹鹼和10-羥基喜樹鹼是喜樹(Camptotheca acuminata)中所含的兩種天然單萜吲哚類生物鹼，本文報告了它們在喜樹種子吸漲和幼苗發育過程中的變化規律。胚乳的喜樹鹼含量比種子的其他部位高2-3倍。在種子的吸漲過程中，胚乳的喜樹鹼含量明顯下降，而其他部位的喜樹鹼含量呈小幅波動。喜樹種子的10-羥基喜樹鹼含量遠低於喜樹鹼含量，而子葉和胚軸的10-羥基喜樹鹼含量比胚乳和種皮更低。伴隨喜樹幼苗的發育過程，子葉的喜樹鹼和10-羥基喜樹鹼含量在9-15天苗齡時最高，胚軸的喜樹鹼含量呈對數下降而10-羥基喜樹鹼含量的變化與子葉相同，胚根的喜樹鹼含量相對穩定而10-羥基喜樹鹼含量則逐漸降低，不過胚根的喜樹鹼和10-羥基喜樹鹼含量均很低。真葉的喜樹鹼含量在幼苗發育過程中線性降低。上述結果表明，喜樹鹼和10-羥基喜樹鹼的分佈存在組織特異性並為發育時期所調控。

關鍵字

喜樹；喜樹鹼； 10-羥基喜樹鹼；調控

並列摘要

Camptothecin (CPT) and its analogue 10-hydroxycamptothecin (HCPT) are two naturally occurring monoterpene indole alkaloids in Camptotheca acuminata. They both show potential efficacy as anti-cancer compounds as well as act as defensive chemicals in plants. Here we report the regulation of CPT and HCPT contents in C. acuminata during seed imbibition and seedling development. The levels of CPT in endosperm was 2 to 3 fold higher than in other tissues, and clearly decreased during the imbibition period. In other tissues, CPT contents exhibited slight fluctuations. In comparison, HCPT contents in all the tissues were much lower. HCPT was less abundant in cotyledon and embryonal axis than in endosperm and seed coat. During seedling development, CPT and HCPT contents in cotyledons reached maximum at 9-15 days stage. In embryonal axis, CPT contents decreased logarithmically, while HCPT content followed the same pattern as in cotyledons. CPT and HCPT levels in radicles were very low, with CPT levels remaining constant and HCPT levels decreasing during development. In leaves, the contents of CPT showed linear reduction during seedling growth. These results demonstrate that the levels of CPT and HCPT are tissue- specifically and developmentally regulated. The physiological implications and significance of the regulation are discussed.

並列關鍵字

Camptotheca acuminata ； Camptothecin ； 10-hydroxycamptothecin ； Regulation

國際替代計量

Tissue-specific and Developmental Regulation of Camptothecin and 10-hydroxycamptothecin Levels in Camptotheca acuminate

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