This project was an investigation of the regulation of PAL induction, following elicitation of cell cultures of<i>Capsicum frutescens</i>, and its effects on phenylpropanoid metabolism. It was shown that the response of PAL specific activity to elicitation increased throughout the culture cycle and consequently, stationary-phase cultures were used throughout the investigation. PAL activity in <i>Capsicum</i> cultures increased transiently after elicitation. Detailed investigation of the initial stages of elicitation showed that PAL activity was induced 40 min after the onset of the elicitor treatment and reached a maximum after <i>ca</i>. 8 h. <i>Capsicum</i> PAL protein sub-units were identified and the molecular size was estimated to be 77 kD, the same size as PAL sub-units isolated from parsley leaves. <i>In vivo</i> labelling techniques showed that the transient induction of PAL specific activity following elicitation resulted from a combination of the general induction of protein synthesis and a specific induction of PAL protein synthesis. Additionally, the synthesis of a 32 kD protein, probably a chitinase precursor, was transiently induced with a lag phase of 4-8 h. A 70 kD polypeptide, possibly a degradation product of PAL sub-units, was recognised by anti-(parsley PAL) serum in samples from elicited and control cultures of<i>Capsicum frutescens</i> but not in <i>Petroselinum</i> samples. PAL mRNA was identified and its molecular size was estimated to be 2.6 kb. Increased PAL mRNA steady state levels were detected following dilution and elicitation. The transient increase in PAL mRNA levels during elicitation followed the same pattern as PAL protein accumulation, thus indicating that the induction of PAL is regulated at the transcriptional level. Elicitation of <i>Capsicum</i> cultures increased PAL mRNA levels transiently resulting in <i>de novo</i> synthesis of PAL protein and, thus, increased PAL activity.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:651844 |
| Date | January 1992 |
| Creators | Groskurt, Ernst Eugen |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/10931 |
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