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A study of the South African tomato curly stunt virus pathosystem: epidemiology, molecular diversity and resistance

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dc.contributor.advisor Dr. H. van Heerden, Prof. M.E.C. Rey; Dr. S.W. van Heerden en_US
dc.contributor.author Esterhuizen, Lindy L.
dc.date.accessioned 2012-11-07T15:20:50Z
dc.date.available 2012-11-07T15:20:50Z
dc.date.issued 2012-11-07
dc.date.submitted 2012-05
dc.identifier.uri http://hdl.handle.net/10210/8152
dc.description PhD en_US
dc.description.abstract In South Africa, tomato (Solanum /ycopersicum) is an important vegetable crop with considerable nutritional and economic value. Over the last decade, begomovirus (family Geminiviridae) infections associated with an upsurge of the whitefly vector, Bemisia tabaci, on tomato crops has become a serious threat to sustainable tomato production in South Africa. Begomovirus disease control in tomato is challenging and requires an integrated "pest" and "vector" management strategy, primarily based on the use of chemical and cultural practices aimed at reducing the virus vector as well as the use of resistant cultivars. Development of effective disease management practices for South Africa therefore requires detailed information on the complex vector-virus-host cropping system interactions. The aim of the study presented in this thesis was to investigate the South African whitefly vector/begomovirus/tomato-host pathosystem, with emphasis on the virus and vector diversity and distribution, and the identification of possible resistance sources. A survey of tomato-infecting begomoviruses was conducted during a six-year period (2006-2011 ). Techniques used to determine begomoviruses diversity included whole genome amplification using PCR, RCA (rolling circle amplification), conventional as well as next generation sequencing and development of a RCA-RFLP (restriction fragment length polymorphism) for rapid assessment of diversity. Sequence comparisons and phylogenetic analyses revealed the presence of three new monopartite begomovirus species, in addition to ToCSV, all of which belong to the African/South West Indian Ocean (SWIO) begomovirus clade. Recombination analysis indicated that all four tomato-infecting begomovirus species appear to be complex recombinants and suggests that they have evolved within the sub-Saharan Africa region, along with other African begomoviruses and that they are most likely indigenous to the region. Several weed species were also confirmed as symptomless begomovirus reservoirs, supporting their role in the emerging begomovirus epidemics in South Africa. en_US
dc.language.iso en en_US
dc.subject Virus diseases of plants en_US
dc.subject Tomatoes - Diseases and pests en_US
dc.subject Begomoviruses en_US
dc.title A study of the South African tomato curly stunt virus pathosystem: epidemiology, molecular diversity and resistance en_US
dc.type Thesis en_US

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