The aim of the work described in this thesis was to assess the role of invertase in carbohydrate metabolism in two red-fruited and hexose-accumulating species, <I>Lycopersicon esculentum</I> and <I>Lycopersicon pimpinellifolium</I>. Fruit from the latter had previously been reported to show a much greater soluble acid invertase activity and correspondingly greater sugar accumulation than that of the former. The pigments chlorophyll a and b, and the carotenoids were measured in developing fruit with the aim of finding a marker for development other than age of the fruit (in days after anthesis). Immuno-gold electron microscopy and immuno-blots were used to determine the intra- and inter-cellular localisation of invertase. Maximal extractable soluble invertase from <I>L. pimpinellifolium</I> PI 126436 fruit was correlated with sugar accumulation during tomato fruit development, whereas no correlation was found during the development of either <I>L. esculentum</I> FM 6203 or <I>L. pimpinellifolium</I> LA 722 fruit. There were three major isoforms of soluble invertase present in <I>L. pimpinellifolim</I> PI 126436 fruit compared with only two major isoforms in <I>L.esculentum</I> FM 6203 or <I>L. pimpinellifolim</I> LA 722 fruit. The activity of invertase appeared earlier in development (i.e. in green fruit) in <I>L. pimpinellifolim</I> PI 126436 fruit than in <I>L. esculentum </I>or <I>L. pimpinellifolium</I> LA 722, where it is virtually absent from green fruit. Tomato fruit produced from progeny of cross between <I>L. esculentum</I> FM 6203 and <I>L. pimpinellifolium </I>PI 126436 (which were selected for the vacuolar invertase gene present) were the used for further investigation. All fruit contained similar fruit sugars and invertase activities regardless of the origin of the gene. It was concluded that the higher soluble solids trait of <I>L. pimpinellifolim </I>PI 126436 fruit may be attributed, at least in part, to invertase activity, as fruit contained at least one major isoform of invertase that was not found in quantity in <I>L. esculentum</I> FM 6203.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:604837 |
| Date | January 1999 |
| Creators | Husain, S. E. |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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