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Title: The role of invertase in the carbohydrate metabolism of tomato fruit
Author: Husain, S. E.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 1999
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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, Lycopersicon esculentum and Lycopersicon pimpinellifolium. 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 L. pimpinellifolium PI 126436 fruit was correlated with sugar accumulation during tomato fruit development, whereas no correlation was found during the development of either L. esculentum FM 6203 or L. pimpinellifolium LA 722 fruit. There were three major isoforms of soluble invertase present in L. pimpinellifolim PI 126436 fruit compared with only two major isoforms in L.esculentum FM 6203 or L. pimpinellifolim LA 722 fruit. The activity of invertase appeared earlier in development (i.e. in green fruit) in L. pimpinellifolim PI 126436 fruit than in L. esculentum or L. pimpinellifolium LA 722, where it is virtually absent from green fruit. Tomato fruit produced from progeny of cross between L. esculentum FM 6203 and L. pimpinellifolium 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 L. pimpinellifolim 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 L. esculentum FM 6203.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available