Eutypa dieback of grapevines, caused by Eutypa lata, is a major cause of reduced longevity in vineyards worldwide. The fungus grows in the woody tissue of infected vines, producing translocatable toxins that cause foliar symptoms of the disease. By the time foliar symptoms are evident the pathogen may have become well established in the vine. One aim of this study was to develop DNA markers to allow rapid reliable identification of E. lata and to detect the pathogen in infected wood. The second aim was to analyse secondary metabolite production by E. lata in order to gain information on the compounds responsible for the foliar symptoms of the disease and to identify metabolites which could be used as markers to detect the early stages of the disease prior to the expression of foliar symptoms. In addition, genetic variation of the pathogen was assessed using RFLP and RAPD analysis. Two techniques were used to develop DNA markers; first, SCAR markers derived from RAPD fragments were developed and, second, an E. lata genomic DNA library was constructed, from which DNA fragments specific to E. lata were identified. These markers were used in either PCR- or Southern hybridisation-based assays to detect the pathogen in infected wood. PCR-based detection of the pathogen in infected wood was prone to inhibition by phenolic compounds, however, Southern hybridisation techniques were capable of detecting E. lata in wood. Genetic variation among 38 isolates of E. lata was assessed using six randomly selected clones from the genomic DNA library. A subset of 11 isolates was subjected to RAPD analysis using 10 random primers. Considerable genetic diversity, in terms of RFLP and RAPD profiles, was observed among isolates. There was no apparent correlation between grouping of isolates following neighbour joining analysis and either host species or geographic origin of isolates. The RAPD and RFLP profiles of two isolates differed significantly from the majority of the other isolates. These isolates, which were morphologically similar to all other isolates, were subsequently found not to be E. lata. Secondary metabolite production of 11 isolates was analysed by HPLC following growth on a range of media. A wider range of secondary metabolites was detected in E. lata than has previously been reported. Two of the secondary metabolites, eutypine and an unidentified compound with a retention time of 19.6 min, were produced by eight of nine isolates of E. lata. Neither of the non-E. lata isolates produced these compounds. It was concluded that the remaining isolate of E. lata may have lost the ability to produce these compounds following storage. Whilst a wider range of isolates needs to be screened before a candidate marker can be selected, these results suggest that certain compounds are present in the majority of E. lata isolates and, hence, may prove suitable markers for the detection of the pathogen prior to the expression of foliar symptoms. The molecular probes developed in this study will allow the rapid and reliable identification and detection of E. lata in grapevine cane or wood. These probes also have the potential to be used as a research tool to gather information on the epidemiology of the disease and to assess the efficacy of potential control agents against E. lata. Suitable control measures could then be applied to vines which have been shown by the use of chemical markers to have latent infection. Used in combination, therefore, the DNA and biochemical markers could facilitate improved management of eutypa dieback. / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture and Wine, 2003.

The behaviour of pigments in red wine, namely anthocyanins and anthocyaninderived pigments, was investigated at natural wine pH, at low pH and after addition of SO2, namely SO2 bleaching. An examination of current literature demonstrated absences in wine pigment research. Firstly, few researchers have published the colour properties of a particular wine pigment at different pH values and post-SO2 bleaching. This was demonstrated using the CIELab colours of two individual anthocyanin-derived wine pigments (4-vinylcatechol and 4-vinylsyringol adducts to malvidin 3-glucoside), and an anthocyanin, malvidin 3-glucoside. The colours of the anthocyanin-derived pigments and their resistance to pH change and SO2 bleaching were compared to malvidin 3-glucoside which was affected by media. Generally, in the literature, wine pigments are characterized as individual components. But many pigments contribute to wine colour. So, two novel methods were created and demonstrated using red wines: Shiraz wines from four regions in Australia, and Cabernet Sauvignon wines made using two different strains, Saccharomyces cerevisiae (SC) or Saccharomyces bayanus (SB). The first method can be used to determine the CIELab colour of chromatographically separated wine pigments and allows their colours to be re-created, regardless of their identity. Thus objective measurement of pigment colour at its natural concentration in wine is now possible. An additional method, the “post-column adjustment method” to pH-adjust and SO2 bleach HPLC-separated wine pigments was created. The concentration and colour of HPLC-separated wine pigments at low pH, at wine pH and post-SO2 bleaching can be measured. The method has highlighted the importance of the pH value when quantifying a wine pigment. For example, from low pH to wine pH, the apparent anthocyanin and pigmented polymer concentration was reduced, but the Vitisin A concentration was unchanged. SO2 bleaching resulted in negligible anthocyanin concentration and a further reduction in pigmented polymer concentration, with Vitisin A unaffected. Relative quantities of wine pigments in both SC and SB Cabernet Sauvignon wines were not affected by pH change or SO2 bleaching. Also, using the Shiraz wines and Cabernet Sauvignon red wines, existing and improved colour measurement techniques were discussed. For the Australian Shiraz wines, grape origin was found to influence red wine colour, CIELab values provided enhanced colour measurements, and high wine colour (at natural wine pH) cannot be attributed to individual monomeric anthocyanins (measured by HPLC analysis at low pH). Vitisin A was not responsible for differences in wine colour. SO2-stable wine colour was related to regional differences. The percentage of SO2 non-bleachable pigments was independent of wine region. Chemical index (ii) values indicated that the colour at 520 nm was attributable to pH-dependent wine pigments. Vitisin A and pigmented polymer concentrations correlated well with SO2-stable wine colour. Pigmented polymer concentration may be the driving force behind wine colour density. Copigmentation was of no importance in the young red wine samples studied. With the Cabernet Sauvignon red wines, the yeast strains used for fermentation affected wine colour and SO2-stable wine colour. The change in wine colour density was not related to change in total red pigment colour or anthocyanin concentration. Pigmented polymer concentration, SO2-stable wine colour and the percentage of SO2 non-bleachable pigments were consistently higher in the SB wines. The pH value was important when determining the colour of a wine or pigment. At low pH, the SC wines were more coloured than the SB wines. However, at real wine pH, the converse was true. For both wines, at low pH, the anthocyanin concentration was greater than the pigmented polymer concentration, indicating the importance of anthocyanins to wine colour only at low pH. But, at wine pH, the apparent anthocyanin concentration was much lower in both wines (for example, malvidin 3- glucoside provided more colour at low pH than at wine pH) than the apparent pigmented polymer concentration. Therefore, at wine pH, anthocyanins were less important to wine colour than pigmented polymers. The concentrations of Vitisin A were similar in all three media, but colour losses were observed at wine pH and post-SO2 bleaching. SB Vitisin A was more coloured. At low pH and at wine pH, Vitisin A was more coloured than malvidin 3-glucoside in both wines, even though the apparent Vitisin A concentration was lower. Differences in the colours of the SC and SB pigmented polymers peaks were observed at low pH, at wine pH and following SO2 bleaching. The SB pigmented polymers were darker and more colourful, exhibited more colour absorbance and a slight bathochromic shift of lmax value. From low pH to wine pH and following SO2 bleaching, pigmented polymers become lighter, whilst retaining orange-red hues. / http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1277727 / Thesis (Ph.D.) -- School of Agriculture, Food and Wine, 2007

Bibliography: leaves 209-235. / 235 leaves, [6] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Crop Protection, 1995?

Erratum pages attached to back page. / Bibliography : leaves 125-147. / 147, [41] leaves : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This study was undertaken to derive a strategy to reduce the potential of S. cerevisiae to produce hydrogen sulfide under oenologial conditions by altering the levels of active sulfite reductase in the cell. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 2000

Bibliography: leaves 209-235.

Bibliography: leaves 127-152. The aim of this work is to study viroids in grapevines, particularly their vertical transmission via seeds, during meristem culture and micropropagation. There was also an attempt to produce viroid-free vines by shoot apical meristem culture (SAMC).

Copies of author's previously published works inserted. Addendum enclosed in pocket on back end paper. Bibliography: leaves 192-221.

This study reports finding of two rootstock experiments planted in 1997. The purpose of the first experiment was to evaluate the performance of Pinot noir on 19 phylloxera-resistant rootstocks and as an ungrafted vine. The purpose of the second experiment was to evaluate the performance of V. Vinifera cultivars Pinot noir, Chardonnay, Pinot gris and Merlot grafted to nine phylloxera-resistant rootstock, and as ungrafted vines. Data for both experiments were collected in 2000 and 2001, the fourth and fifth years of establishment respectively. Vines received supplemental irrigation and were fertilized with N-P-K during both seasons. In the first experiment, rootstock affected vegetative growth, chlorophyll content, yield, cluster weight and berry weight in both years, gas exchange measurements in 2000, and fruit composition in 2001. Of the V. riparia x V. rupestris rootstocks, 3309C and Schwarzmann imparted low to moderate vigor, as reflected by pruning weight. 101-14 Mgt imparted higher vigor to Pinot noir than 3309C. Based on ripening index values (soluble solids/titratable acidity, Brix/TA), ripening appeared to be earlier for vines grafted to 101-14 Mgt and Schwarzmann than for 3309C. The V. berfandieri x V. riparia rootstocks, including 161-49C and 420A, imparted average to higher than average vigor. Ripening appeared to be later than average and berries larger than average for vines grafted to these rootstocks. With the exception of 110R, the V. berlandieri x V. rupestris rootstocks had higher than average vigor. Ripening times seemed to be average and berry weights were higher than average for vines grafted to these rootstocks. Of the remaining-rootstocks 1616C performed much like the V. berlandieri x V. rupestris rootstocks with an even higher ripening index. Borner, Riparia Gloire, 44-53 Malegue and Gravesac all imparted low to moderate vigor. Berry weights tended to be average to lower than average. Riparia Gloire and Gravesac seemed to impart earlier ripening, while Borner and 44-53 Malegue did not. In the second experiment, the V. berlandieri x V. riparia rootstocks imparted more vigor, a higher yield, a higher berry weight and delayed ripening as reflected by the ripening index. 101-14 Mgt imparted a higher pruning weight, lower berry weight and earlier ripening than 3309C. 110R, 44-53 Malegue and Gravesac conferred moderate vigor as reflected by pruning weight. Riparia Gloire conferred lower vigor. Ripening times imparted by these rootstocks ranged from early for Riparia Gloire and Gravesac, to average for 110R and later for 44-53 Malegue. Berry weights were average for scion grafted to 110R and Gravesac, and low for scion grafted to Riparia Gloire and 44-53 Malegue. / Graduation date: 2002

Thesis (Ph. D.)--University of California, Davis, 2003. / Degree granted in Agricultural and Environmental Chemistry. Also available via the World Wide Web. (Restricted to UC campuses).

Thesis (MSc)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.