Valine Pathway Is More Crucial than Phenyl Propanoid Pathway in Regulating Capsaicin Biosynthesis in Capsicum frutescens Mill.

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• 作者：Bellur Chayapathy Narasimha Prasad ; Harishchandra Bhaskar Gururaj ; Vinod Kumar ; Parvatam Giridhar ; Gokare Ashwathnarayana Ravishankar
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2006
• 出版时间：September 6, 2006
• 年：2006
• 卷：54
• 期：18
• 页码：6660 - 6666
• 全文大小：171K
• 年卷期：v.54,no.18(September 6, 2006)
• ISSN：1520-5118

文摘

Capsaicin, a pungency factor alkaloid of Capsicum fruits, is biosynthesized by enzymatic condensationof vanillylamine, a phenyl propanoid intermediate, and 8-methyl-nonenoic acid, a fatty acid derivativefrom the leucine/valine pathway by capsaicin synthase. Biotic elicitors, such as aqueous mycelialextracts of Rhizopus oligosporus and Aspergillus niger, and abiotic elicitors, such as salicylic acidand methyl jasmonate, were incorporated to cell-suspension cultures of Capsicum frutescens. Themaximum elicitation of capsaicinoids to the extent of 6-folds was noticed when mycelial extracts ofR. oligosporus were incorporated to cell-suspension cultures. The phenyl propanoid intermediateswere elicited to the extent of 3-4-fold, whereas the levels of 8-methyl-nonanoic acid increased 6-foldin R. oligosporus mycelial-extract-treated cultures. The enzymatic assays of caffeic acid O-methyltransferases, keto acyl synthase, and capsaicin synthase were performed in elicited and nonelicitedcell-suspension cultures. These enzymes were overexpressed in R. oligosporus mycelial-extract-treated suspension cultures, which was also confirmed by reverse transcriptase polymerase chainreaction studies. This is the first paper on the overexpression of 8-methyl-nonanoic acid leading tocapsaicin biosynthesis using elicitors.