The aim of this project was to study the effects of vanillin and some of its putative precursors on fruits and cultured cells of <I>Capsicum frutescens</I> Mill. and in particular to determine the role of vanillin in capsaicin biosynthesis. When ferulic acid, the putative precursor to vanillin, was supplied to suspension culturers of <I>C. frutescens,</I> no vanillin or capsaicin were detected. Instead, caffeic acid (the precursor to ferulic acid) and an unknown compound, A, were detected in the cells and medium of suspension cultures respectively. When vanillin was supplied to suspension cultures of <I>C. frutescens,</I> vanillyl alcohol and a compound tentatively identified as a vanillic acid glycoside were detected in the medium and cells of suspension cultures respectively. When vanillin was supplied to fruits of <I>C. frutescens</I> prior to the onset of capsaicin synthesis, vanillyl alcohol and a vanillic acid glycoside were produced. In fruits actively accumulating capsaicin, vanillyl alcohol and a vanillin glycoside (B-d-glucosidovanillin) appeared after the addition of vanillin. However, both were transient metabolites and the fate of most of the added vanillin is still unknown. Certain amounts of added vanillin appeared to increase the amount of [<SUP>14</SUP>C]phenylalanine incorporated into capsaicinoids, glycosylated and saponified cell wall phenolics in fruits of <I>C. frutescens. </I>This led to the tentative conclusion that vanillin stimulated phenylpropanoid metabolism thus increasing the flux of [<SUP>14</SUP>C]phenylalanine down the pathway. A similar but less well-defined stimulation occurred in suspension cultures where there was an increase in the incorporation of [<SUP>14</SUP>C]phenylalanine into glycosylated phenolics on the addition of vanillin. There was also some indication that vanillin may act as a precursor to lignin as the addition of vanillin caused a decrease in the incorporation of [<SUP>14</SUP>C]phenylalanine into lignin in both fruits and suspended cells of <I>C. frutescens.</I>
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:641696 |
| Date | January 1993 |
| Creators | Bladon, Sarah Jane |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/15003 |
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