Thesis Abstract and Dissertation Abstracts

A survey was conducted with the aim of determining which of sixteen different viruses occur in the greenhouse tomato crop cultivated in the Maltese Islands and establishing the incidence of any viruses identified.

A total of 40 different greenhouses dispersed throughout the northern, central and southern regions of Malta as well as in Gozo were visited and 200 leaf samples were collected from the three most common tomato cultivars grown locally. Leaf sap extracts were tested by DAS-ELISA and results were correlated with field symptomatology. Factor analysis by principal components was also performed to establish any association between viral incidence and tomato variety.

Although general statements about disease symptoms and their correlation to detection of a specific virus could be made, it was difficult to make an accurate diagnosis on the site. The difficulties associated with interpretation of symptomatology were also compounded by the occurrence of multiple infections.

Viral incidence varied from 95.38% for TBRV to 0.50% for CMV. As for the other investigated viruses, the frequency of occurrence in decreasing order was as follows: TYLCV, ToRSV, TEV, TSWV, ToMV, PVY, TRSV, AMV, INSV and PVX. PepMV, PLRV, PVM and TMV were not detected in this survey.

This is the first report of the occurrence of TEV, TBRV and TRSV in the Maltese Islands. CMV, INSV, PVX and TSWV occurred predominantly in the variety Jeffrey. Infections by AMV, ToRSV and TYLCV were mostly associated with Thomas, while PVY and ToMV were most common in Dynamo. An association was also established between Jeffrey and Dynamo and the nepoviruses TRSV and TBRV while both Dynamo and Thomas were found to be equally susceptible to TEV infections.

Viral occurrence in Gozo was considerably low when compared to the situation in Malta. This may be a direct consequence of the more widespread distribution and thus greater spatial separation of greenhouses in Gozo which limits the spread of vector-borne viruses.

In view of symptom expression, TYLCV remains the most economically important viral pathogen of tomato in the Maltese Islands regardless of the fact that tomato varieties which are tolerant to the virus are being cultivated. Other viruses including AMV, CMV, PVY, ToMV and TSWV do not represent a serious threat to the local greenhouse tomato industry. Nonetheless the tomato crop could still provide an alternative host and reservoir for viruses such as PVX and PVY which limit the production of other important crops including potato.

This Thesis Abstract may be cited as follows:
Tanti, R. (2003) Viruses infecting the greenhouse tomato crop (Lycopersicon lycopersicum) in the Maltese Islands. xii+180 pp. B.Sc. (Hons.) Dissertation, Department of Biology, Faculty of Science, University of Malta.

Submission Details: Thesis Abstract submitted by Robert Tanti from Malta on 24-Sep-2003 23:03.
Abstract has been viewed 2691 times (since 7 Mar 2010).

Robert Tanti Contact Details: Email: robertt@nextgen.net.mt