Factors affecting volatile terpene and non-terpene biotransformation products in plant cell cultures

W. Zhu, G. Asghari, G.B. LockwoodU
School of Pharmacy & Pharmaceutical Scienes, Uni¨ersity of Manchester, Manchester M13 9PL,
UK
Received 7 January 2000; accepted in revised form 16 February 2000

Introduction
The production and accumulation of volatile essential oil constituents in plant cell cultures has been reviewed 1,2 . Although plant cells cultured in vitro are considered to be totipotent, i.e. contain all necessary genetic material to carry out any or all of the functions shown by the intact plant, in practice many either fail to produce essential oil constituents or produce a few in only very low levels. It is often accepted that as undifferentiated cultures contain no structures such as trichomes or vittae for storage of these constituents 3 none will accumulate. In many systems particular enzyme systems needed for a biosynthetic step have been shown to be present , but inoperative, and this inhibits production of the end product(s). A number of workers have attempted to improve production and accumulation of these compounds by feeding precursors 1,2 , but levels are still well below those of intact plants. We decided to use a range of techniques to investigate if levels of biotransformation products could be increased. Biotransformation of geraniol acetate to geraniol by plant cell cultures has not previously been reported, although there is one report of the reverse reaction occurring, in a study of the biogenesis of monoterpenes using cultures derived from Muscat grapes 4.
However, a few reports have described the biotransformation of other terpene acetates into their parent alcohols by plant cell cultures 5,6, but in both instances the parent alcohol was only the major product, not the sole product. In an attempt to show variation in levels of biotransformation of volatile terpenoids and non-terpenoids, we chose suspension cultures of Peganum harmala L._Zygophyllaceae. for the feeding experiments.

Keywords: Peganum harmala; Biotransformation; Essential oil , Suspension cultures


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