Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The aim of this study on grapevine was to genetically characterise, validate and map the reported fungal disease resistance genes of Pölöskei Muskotály (PM), Kishmish Vatkana (KV) and Villard Blanc (VB) in South Africa using QTL analysis. These fungal resistant parents were crossed with other varieties that have desirable fruit qualities in an effort to combine fungal disease resistance with desirable fruit qualities in a single variety. The genetic basis of PM’s resistance to downy and powdery mildew has not been investigated before. It does however have VB in its pedigree so the assumption was made that the same QTL/genes present in VB contribute to this resistance. KV’s resistance to powdery mildew reportedly originates from the REN1 gene located on chromosome 13. VB’s powdery and downy mildew resistance is conferred by QTL present on chromosome 15 and chromosome 18 respectively and has been reported in numerous studies. The study populations comprised of 124 F1 PM x Regal Seedless plants, 16 F1 PM x G4-3418 plants, 14 F1 PM x Sunred Seedless plants, 158 F1 Sunred Seedless x KV plants and 250 F1 VB x G1-6604 plants. DNA was extracted from the leaves and all plants were screened using microsatellite markers. Phenotypic evaluations of downy and/or powdery mildew resistance were performed on the appropriate populations. The molecular data was used to generate linkage maps and combined with phenotypic data to perform QTL analysis. From the molecular data generated for the three PM populations it was determined that the F1 progeny inherited almost exclusively maternal alleles, and could not be used in a mapping study. These populations were eliminated from the study and PM will be used as a pollen donor in future. Molecular data from the Sunred Seedless x KV cross was used to generate a linkage map for chromosome 13 comprising eight markers and spanning 45.6 cM. When combined with the data from two powdery mildew phenotypic screens a QTL peak spanning the REN1 gene on chromosome 13 of KV was identified. This locus explains between 44.8% and 57.7% of the phenotypic variance observed. The molecular data from the VB x G1-6604 cross was used to generate partial linkage maps for chromosome 15 and 18. Eleven markers were mapped on chromosome 15 spanning 56.4 cM, and ten markers were mapped on chromosome 18 spanning 101.8 cM. When the chromosome 15 linkage map was combined with the data from two powdery mildew phenotypic screens a QTL associated with powdery mildew resistance was identified on chromosome 15 that explains between 18.9% and 23.9% of the phenotypic variance observed. Likewise a QTL associated with downy mildew resistance was identified on chromosome 18 when the chromosome 18 linkage map was combined with data from two downy mildew phenotypic screens. This QTL explains between 19.1% and 21.2% of the phenotypic variance observed. This study succeeded in genetically characterising the fungal disease resistance genes of two different sources of grapevine and provided exclusionary information on a third resistance source for future breeding applications. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie in wingerd was om die genetiese komponent van die swamweerstandsgene van Pölöskei Muskotály (PM), Kishmish Vatkana (KV) and Villard Blanc (VB) in Suid-Afrika te karakteriseer en die teenwoordigheid daarvan te bevestig deur ʼn Kwantitatiewe Eienskap Lokus (KEL) benadering te volg. In ʼn poging om swamweerstand en goeie vrugeienskappe te kombineer in ʼn enkel variëteit is die weerstandige variëteite met vatbare variëteite gekruis wat goeie vrugeienskappe besit. Die genetiese basis van PM se weerstand teen donsskimmel en witroes is nog nie vantevore bestudeer nie. VB is een van sy voorgeslagte en daar is aangeneem dat dieselfde KEL/gene waarskynlik verantwoordelik is vir die weerstand. Dit is gerapporteer dat KV se witroesweerstand afkomstig is van die REN1 geen op chromosoom 13. Vele publikasies rapporteer VB se weerstand teen witroes en donsskimmel Beide die witroes- en donsskimmelweerstand word oorgedra deur KEL teenwoordig op chromosome 15 en 18 onderskeidelik. Die populasies gebruik in hierdie studie het bestaan uit 124 F1 PM x Regal Seedless plante, 16 F1 PM x G4-3418 plante, 14 F1 PM x Sunred Seedless, 158 F1 Sunred Seedless x KV plante en 250 F1 VB x G1-6604 plante onderskeidelik. Blare is versamel vir DNS isolasie en genotipering met mikrosatellietmerkers. Al drie populasies se weerstand teen donsskimmel en/of witroes is fenotipies geëvalueer. Die molekulêre data is gebruik om genetiese koppelingskaarte op te stel en gekombineer met die fenotipiese data om KEL analise uit te voer. Die molekulêre data van die drie PM populasies het daarop gedui dat die F1 nageslag amper uitsluitlik moederlike allele geërf het en kon gevolglik nie gebruik word in die studie nie. Die PM populasies is uitgesluit uit hierdie studie en PM sal voortaan as stuifmeelskenker gebruik word. Molekulêre data van die Sunred Seedless x KV kruising is gebruik om ʼn koppelingskaart vir chromosoom 13 op te stel wat 45.6 cM lank is en agt merkers bevat. Die KEL analise van die koppelingskaart en twee fenotipiese datastelle vir witroes het ʼn KEL piek geïdentifiseer wat oor die lengte van die REN1 geen-interval strek. Hierdie lokus is verantwoordelik vir 44.8% tot 57.7% van die fenotipiese variasie wat waargeneem word. Molekulêre data van die VB x G1-6604 kruising is gebruik om gedeeltelike koppelingskaarte vir chromosome 15 en 18 op te stel. Elf merkers karteer op die chromosoom 15 kaart van 56.4 cM en tien merkers karteer op die chromosoom 18 kaart van 101.8 cM. KEL analise van chromosoom 15 se koppelingskaart en twee witroes fenotipiese datastelle het ʼn KEL geïdentifiseer wat 18.9% tot 23.9% van die fenotipiese variasie verduidelik. ʼn KEL is ook op chromosoom 18 geïdentifiseer wat 19.1% tot 21.2% van die fenotipiese variasie verduidelik met die gekombineerde analise van chromosoom 18 se koppelingskaart en twee donsskimmel fenotipiese datastelle. Hierdie studie het die genetiese komponent van die swamweerstandsgene van twee Vitis variëteite suksesvol gekarakteriseer en bevestig. Waardevolle telingsinligting oor die derde variëteit is ook onthul.