The cytopathological and molecular studies of cacao swollen shoot virus (CSSV) infected cocoa plants, which was aimed at identifying structural and functional changes associated with CSSV infections that can be used as resistant markers has yielded interesting results. Nucleic-acid-rich spherical inclusion bodies, modified plastids, invagination of cell walls, apoptotic cells, massive deposition of phenolic substances in infected cells, in situ localisation of CSSV particles in novel cocoa tissues and the apparent aggregation of starch granules in infected tissues were changes that were found to be accompanying CSSV infection by microscopy. Since most of these discoveries were new in CSSV research, they were validated using PCR (conventional and quantitative (qPCR», flow cytomefry (FCM) and laser scanning confocal microscopy (LSCM). The qPCR assay, which was developed from the scratch to measure the CSSV content in infected cocoa plants, has since been used to start building profiles of CSSV resistant cocoa cultivars from Ghana. It was also used to· compare the viral load between the cotyledons and leaves of an infected cocoa plant, whereby the cotyledons were found to have 4-folds more CSSV than the leaves. The qPCR assay has also been used to start studying the movement of CSSV in infected cocoa plants. The FCM was used to confirm apoptotic outcome in CSSV infected plants. This was shown by a reduction in total nuclei DNA between infected and healthy plants at magnitudes which correspond to the microscopic observations. Results from the LSCM were inconclusive. Light microscopic analysis of nucleicacid- rich inclusion bodies, which would have added to building a more robust profile ofthe CSSV resistant cocoa cultivars from Ghana could not be completed due to time constraints. The significance of all these findings in breeding ~or CSSV resistant cocoa, and in CSSV research is discussed.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:485583 |
| Date | January 2008 |
| Creators | Dzahini-Obiatey, Henry Kwame |
| Publisher | University of Reading |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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