One hundred and eighty six F 1 plants from a 'Regent' 9 'RedGlobe' cross were used to generate a partial linkage map with 139 microsatellite markers spanning all 19 chromosomes. Phenotypic scores for downy mildew, taken over two years, confirmed a major resistance QTL (Rpv3) against downy mildew in the interval VVIN16-cjvh to UDV108 on chromosome 18 of 'Regent'. This locus explained up to 62 % of the phenotypic variance observed. Additionally a putative minor downy mildew resistance locus was observed on chromosome 1 in one season. A major resistance locus against powdery mildew (Ren3) was also identified on chromosome 15 of 'Regent' in the interval UDV116 to VChr15CenGen06. This study established the efficacy of and validated the 'Regent'-derived downy and powdery mildew major resistance genes/QTL under South African conditions. Closely linked SSR markers for marker-assisted selection and gene pyramiding strategies were identified.

No abstract

No abstract

No abstract

This study examined the value of field experience as a component of study for international students in a Graduate Teacher Education program at a Midwestern liberal arts university. The purpose of the field experience was to provide a contextual basis for student learning. The espoused research method included a quantitative component via survey and qualitative data, through a focus group interview and participants' field notes. As a result, there is evidence to suggest that the field experience program, as a component of the graduate education program for international students was valuable. Participants described it as being relevant and real. As evident from the field notes, participants reflected on the opportunity for cross-cultural application of their learning, while emphasizing that the learning was palpable and reinforced their conceptual learning. Through the field experience program, participants reported that they gained in-depth insight on leadership and classroom instruction; therefore, they were able to improve their craft as educational leaders. Moreover, evidence from this study also suggests that participants were prepared to approach meaningful educational reform upon returning to their homeland, in Saudi Arabia.

Volatile organic compounds such as terpenes influence the quality parameters of grapevine through their contribution to the flavour and aroma profile of berries. Biosynthesis of volatile organic compounds in grapevine is relatively complex and controlled by multiple genes, the majority of which are unknown or uncharacterised. To identify the genomic regions that associate with modulation of these compounds in grapevine berries, volatile metabolic data generated via GC-MS from a grapevine mapping population was used to identify quantitative trait loci (QTLs). Several significant QTLs were associated with terpenes, and candidate genes were proposed for sesquiterpene and monoterpene biosynthesis. For monoterpenes, loci on chromosomes 12 and 13 were shown to be associated with geraniol and cyclic monoterpene accumulation, respectively. The locus on chromosome 12 was shown to contain a geraniol synthase gene (VvGer), while the locus on chromosome 13 contained an α-terpineol synthase gene (VvTer). Molecular and genomic investigation of VvGer and VvTer revealed that these genes were found in tandemly duplicated clusters, displaying high levels of hemizygosity. Gene copy number analysis further showed that not only did VvTer and VvGer copy numbers vary within the mapping population, but also across recently sequenced Vitis cultivars. Significantly, VvTer copy number correlated with both VvTer gene expression and cyclic monoterpene accumulation in the mapping population. A hypothesis for a hyper-functional VvTer allele linked to increased gene copy number in the mapping population is presented and can potentially lead to selection of cultivars with modulated terpene profiles. The study highlights the impact of VvTPS gene duplication and copy number variation on terpene accumulation in grapevine.

This study aimed to validate the effectiveness and to genetically characterise the fungal disease resistance genes of 'Kishmish Vatkana' and 'Villard Blanc' in South Africa using microsatellite (SSR) markers and a Quantitative Trait Loci (QTL) approach. An F 1 'Sunred Seedless' × 'Kishmish Vatkana' cross was used to generate a partial linkage map for chromosome 13 known to harbour the Ren1 powdery mildew locus of 'Kishmish Vatkana'. The effectiveness of this locus was validated, explaining between 44.8% and 57.7% of the observed phenotypic variance. An F 1 'Villard Blanc' × 'G1-6604' cross was used to generate partial linkage maps for chromosomes 15 and 18, reported to harbour fungal resistance genes of 'Villard Blanc'. The powdery mildew QTL (Ren3) was validated on chromosome 15 of 'Villard Blanc', which explained between 18.9% and 23.9% of the phenotypic variance observed. The downy mildew resistance QTL on chromosome 18 (Rpv3) of 'Villard Blanc' was also confirmed, and it explained between 19.1% and 21.2% of the phenotypic variance observed. This molecular information and individual sources of resistance have already been implemented in the marker-assisted selection (MAS) and gene pyramiding efforts of the table grape breeding program of the Agricultural Research Council (ARC) Infruitec-Nietvoorbij.

No abstract