Revised / 2 pp.

Association mapping (AM), based on linkage disequilibrium, is a complementary strategy to traditional quantitative trait loci (QTL) mapping for describing associations between genotypes and phenotypes in crop plants. Yellow endosperm colour, an important quality trait in durum wheat (<i>Triticum turgidum L. var. durum</i>), was studied to determine the potential of AM to (1) identify previously reported QTL using a genome wide scan and (2) to determine allelic association of the phytoene synthase 1 (Psy1) gene using a candidate gene analysis. At present, a number of QTL for endosperm colour have been identified, and phytoene synthase, the initial enzyme of the carotenoid biosynthetic pathway, has been associated with QTL on the group 7 chromosomes which are considered to play a significant role in expression of yellow pigment concentration. CIE 1976 b*, a light reflectance measurement, and water-saturated butanol extracted pigments were assessed on a collection of 93 elite accessions from a variety of geographic origins, and genotyped with 245 markers. Population structure was assessed using genetic distance and Bayesian model based approaches, identifying five sub-populations consistent with breeding origin and pedigree. Association analysis identified significant associations with yellow endosperm colour on all chromosomes, including several previously identified QTL as well as new regions for genomic dissection. Pairwise LD mapping of Psy1-B1 and Psy1-A1 located the genes to chromosomes 7B and 7A respectively, to regions which have previously been identified for yellow pigment concentration QTL. The results of this study indicate that AM can be used to complement traditional QTL mapping techniques, and identify novel QTL for further study.

Yellow pigment (YP) concentration is an important quality trait in durum wheat (<i>Triticum turgidum</i> L. var <i>durum</i>) and is comprised primarily of carotenoids. The main objective of our study was to measure the accumulation of carotenoids during the grain fill period to improve our understanding of the physiological basis for differences among durum wheat cultivars. Thirteen cultivars and breeding genotypes with large variation in total YP concentration (<6 µg g-1 to >15 µg g-1) were studied. Spikes were sampled from replicated field plots in 2007 and 2008 near Saskatoon and Swift Current, Saskatchewan, Canada, at 14, 21, 28 and 35 days after heading (DAH). The remainder of each plot was combined at grain maturity for YP and carotenoid analysis. Carotenoids were extracted with 1:1 methanol:dichloromethane (0.1% BHT) and quantified with HPLC. <i>Trans</i> (E)-lutein was the predominant carotenoid at maturity and was detected at 14 DAH in all genotypes. The rate and duration of E-lutein accumulation was variable among genotypes expressing high, intermediate and low YP. The accumulation of all carotenoids was lowest in genotypes expressing low YP, and suggests rate limitations early in the carotenoid biosynthetic pathway. E-zeaxanthin concentrations were highest in mature grain, but no significant differences were detected among genotypes. However, the ratio of E-zeaxanthin to E-lutein was inversely correlated with total YP, suggesting that the â,å branch of lycopene cyclization is favoured over the â,â branch in high-YP genotypes. These results provide insights to the regulation of the carotenoid biosynthetic pathway during grain fill stage in durum wheat and will facilitate breeding for higher carotenoid concentration.

Ergot, caused by the fungal pathogen Claviceps purpurea (Fr.) Tul., attacks the floral organs of many grassy species resulting in sclerotia production rather than grain. Infection causes reduced yields, downgrading, and poisoning if consumed by humans or animals. Few recent studies have been conducted on ergot in wheat (Triticum spp.), and prevention is the only means of control. The objectives of this study were to determine if western Canadian spring wheat differed in reaction to infection with C. purpurea and if levels of inoculum would affect disease intensity in a field setting. Three variables were measured for the field experiments to determine disease reaction, including percent sclerotia by weight, number of sclerotia per spike, and weight per sclerotium. In the first experiment, nine wheat cultivars were tested using three inoculum levels. No significant differences were detected among inoculum levels. In the second and third experiments, ninety-two cultivars were studied in field and controlled conditions. Honeydew production, sclerotial size, and the percent of florets aborted were added as variables in the growth chamber experiment. Pearson correlations were calculated using cultivar means for the field and controlled environments. Results indicate that there are differences in disease reaction among cultivars and market classes, but these differences varied depending on the evaluation method used. In the field, CWAD wheat had the smallest sclerotia, but had more per spike compared to the CWRS and CWES market classes. There were no significant differences among these market classes for percent sclerotia by weight. In the growth chamber, CWAD wheat generally had the lowest ergot infection levels. When comparing the market classes within T. aestivum (CWRS, CPS, and CWES), there were no significant differences except for honeydew production. The correlation between environments was not significant for any of the variables, suggesting alternate resistance mechanism expression. In the field, reduced infection may be due to an escape mechanism, while artificial inoculation in a controlled environment may detect a physiological resistance mechanism. However, a group of cultivars with Grandin parentage showed promising results in both environments, and might confer resistance that could be integrated into disease resistance breeding programs.

Association mapping (AM), based on linkage disequilibrium, is a complementary strategy to traditional quantitative trait loci (QTL) mapping for describing associations between genotypes and phenotypes in crop plants. Yellow endosperm colour, an important quality trait in durum wheat (<i>Triticum turgidum L. var. durum</i>), was studied to determine the potential of AM to (1) identify previously reported QTL using a genome wide scan and (2) to determine allelic association of the phytoene synthase 1 (Psy1) gene using a candidate gene analysis. At present, a number of QTL for endosperm colour have been identified, and phytoene synthase, the initial enzyme of the carotenoid biosynthetic pathway, has been associated with QTL on the group 7 chromosomes which are considered to play a significant role in expression of yellow pigment concentration. CIE 1976 b*, a light reflectance measurement, and water-saturated butanol extracted pigments were assessed on a collection of 93 elite accessions from a variety of geographic origins, and genotyped with 245 markers. Population structure was assessed using genetic distance and Bayesian model based approaches, identifying five sub-populations consistent with breeding origin and pedigree. Association analysis identified significant associations with yellow endosperm colour on all chromosomes, including several previously identified QTL as well as new regions for genomic dissection. Pairwise LD mapping of Psy1-B1 and Psy1-A1 located the genes to chromosomes 7B and 7A respectively, to regions which have previously been identified for yellow pigment concentration QTL. The results of this study indicate that AM can be used to complement traditional QTL mapping techniques, and identify novel QTL for further study.

Yellow pigment (YP) concentration is an important quality trait in durum wheat (<i>Triticum turgidum</i> L. var <i>durum</i>) and is comprised primarily of carotenoids. The main objective of our study was to measure the accumulation of carotenoids during the grain fill period to improve our understanding of the physiological basis for differences among durum wheat cultivars. Thirteen cultivars and breeding genotypes with large variation in total YP concentration (<6 µg g-1 to >15 µg g-1) were studied. Spikes were sampled from replicated field plots in 2007 and 2008 near Saskatoon and Swift Current, Saskatchewan, Canada, at 14, 21, 28 and 35 days after heading (DAH). The remainder of each plot was combined at grain maturity for YP and carotenoid analysis. Carotenoids were extracted with 1:1 methanol:dichloromethane (0.1% BHT) and quantified with HPLC. <i>Trans</i> (E)-lutein was the predominant carotenoid at maturity and was detected at 14 DAH in all genotypes. The rate and duration of E-lutein accumulation was variable among genotypes expressing high, intermediate and low YP. The accumulation of all carotenoids was lowest in genotypes expressing low YP, and suggests rate limitations early in the carotenoid biosynthetic pathway. E-zeaxanthin concentrations were highest in mature grain, but no significant differences were detected among genotypes. However, the ratio of E-zeaxanthin to E-lutein was inversely correlated with total YP, suggesting that the â,å branch of lycopene cyclization is favoured over the â,â branch in high-YP genotypes. These results provide insights to the regulation of the carotenoid biosynthetic pathway during grain fill stage in durum wheat and will facilitate breeding for higher carotenoid concentration.

Soft corals of the genus Lobophytum (Alcyoniidae) have been well recognized as a rich source of various secondary metabolites that have attracted much interest for the natural products chemists due to their structural complexity and remarkable pharmacological activities such as cytotoxicity, antibacterial activities, anti-inflammatory properties, and antiviral activity. Twelve cembrane diterpenes including six new secondary metabolites 1−6 were isolated organic extracts of soft coral Lobophytum durum collected at Dongsha Atolls. The structures of these six new cembranolides were determined by 1H, 13C, DEPT, COSY, HMBC, HSQC, NOESY, IR and Mass spectra. Furthermore, these six new secondary metabolites 1−6 were evaluated in vitro for the cytotoxicity against A-459 (human lung carcinoma), HT-29 (human colon adenocarcinoma), and P-388 (mouse lymphocytic leukemia) cancer cell lines, and antiviral activity against HCMV (human cytomegalovirus) cells.

Revised

Two sets of durum samples were used to determine kernel characteristics and milling properties of durum genotypes grown in North Dakota, USA. Kernels were characterized for kernel size (length, width, and thickness), germ size (length and width), and shape (kernel width/kernel length, volume, sphericity, germ width/germ length, germ length/kernel length, and germ width/kernel width). Kernels were also characterized for their test weight, kernel weight, vitreousness and hardness. Milling properties evaluated were break release, milling rate, total extraction, semolina extraction, and semolina quality. All kernel characteristics and milling properties varied with genotype and growing location. First break release and milling rate were influenced by kernel shape and size. Larger, wider, and rounder kernels tended to result in better milling performance in the first break. Kernel hardness and vitreousness were strongly correlated and both were positively correlated to semolina extraction but not total extraction.

Durum wheat (Triticum durum Desf.) is produced primarily in the Northern Great Plains and the Pacific Southwest of the United States. Current germplasm is predominantly of the spring growth habit. The objective of this study was to determine the feasibility of winter durum production in Virginia based upon both yield and quality parameters. Adaptation and yield potential of available winter durum lines were assessed from 1993-1998, in three physiographic regions in Virginia. The highest average durum yields were produced in the northern piedmont plateau at the Orange County location. Winter durum yields generally averaged 1600-2800 kg/ha less than soft red winter wheat, traditionally grown in the state. The price premium for high quality durum can compensate for this difference in yield. Based on average durum yields, and assuming the grain meets U.S. No. 2 Hard Amber Durum standards, durum production in Virginia would have been more profitable than soft red winter wheat production in 1994 and 1997. Physical and chemical quality analyses of the top 19 performing durum lines were performed to determine grain marketability, suitability for pasta, and potential consumer acceptance of the end product. Protein content and gluten strength of the Virginia grown durum were acceptable. Color, firmness, and cooking loss of pasta produced from Virginia grown durum were comparable to pasta produced from commercial semolina. Requirements for U.S. No. 2 Amber Durum were met by 21% of the lines in both 1996 and 1997. Overall, the wet, humid Virginia climate was the greatest hindrance to durum production and quality. The field trials and quality analyses showed that high quality durum production in Virginia is possible, but not consistent over all years. / Master of Science