Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 184-188).

Thesis (Ph. D.)--University of Wisconsin, 1965. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Sorghum is a staple food in the semi-arid tropics of Asia and Africa, sustaining the lives of the poorest rural people. This project set out to improve the potential economic value of Sorghum bicolor as a crop. The task was undertaken by screening for selected enzymes in the plant that would have a potential market for use in industrial applications and in biotransformations, specifically proteases, polyphenol oxidases and peroxidases. Asurveywas conducted using standard enzyme assays and crude plant extracts, to determine whether the selected enzymes were present. Grain tissue did not appear to have significant protease or polyphenoloxidase activity, but high levels of peroxidases were detected, withthe young grain extracts showing more activity(4.63U/mL)thanripegrain extracts (0.62 U/mL). Leaf tissue extracts contained low levels of protease activity, a considerable amount of polyphenol oxidase (0.127 U/mL), and peroxidase (4.7 U/mL) activities comparable with that found in grain tissue. Root tissue extract was found to contain the highest levels of peroxidase activity (7.8 U/mL) compared to the other extracts. Therefore, sorghum peroxidase from the root was isolated, purified, characterized and applied to biotransformation reactions. Different sorghum strains,withvaryinggraincolour, (Zimbabwe - bronze, Seredo - brown and Epurpur - cream/white) were investigated for the presence of polyphenol oxidase and peroxidase activities. Results of spectrophotometric analysis showed that the enzymes did not appear to be strain specific. However, gel electrophoresis analysis revealed differences in band patterns among the strains. Partial purification of sorghum root peroxidase was achieved after centrifugation, extraction with polyvinylpolypyrrolidone (PVPP), ultrafiltration, and hydrophobic chromatography with phenyl Sepharose, followed by polyacrylamidegelelectrophoresis (PAGE). The specific activity of the 5-fold purified enzyme was found to be 122.3 U/mg. After PAGE analysis, two bands with molecular weights of approximately 30 000 and 40 000 were detected, which compares well with horse radish peroxidase (HRP) which has a molecular weight of approximately 44 000. The colour intensity of the bands in the activity gels indicated that sorghum root peroxidase had apparently higher levels of peroxidase activity than commercial horseradish peroxidase (HRP). Characterizationexperiments revealed that sorghumroot peroxidase is active over a broad temperature range and remains active at temperatures up to 100°C. It also has a broad substrate range. The optimum pH of the enzyme was found to be pH 5 - 6. Under standardized assay conditions, the optimal substrate concentration, using o-dianisidine as substrate, was 50 mM, and the optimal H2O2 concentration under these conditions was found to be 100 mM. Sorghum root peroxidase was applied in a preliminary investigation into the oxidative biotransformationof a number of aromatic compounds. The products obtained were comparable withthose whenthe compounds are reacted with HRP which is the most commonly used commercial peroxidase and has been extensively studied. However, HRP is relatively costly, and the use of peroxidase from sorghum roots as an alternative source, appears to be promising. A patent has been provisionally registered, covering application of sorghum root peroxidase for biotransformations.

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Petroleum prices have made alternative fuel crops a viable option for ethanol production. Sweet sorghum [Sorghum bicolor] is a nonood crop that may produce large quantities of ethanol with minimal inputs. Eleven cultivars were planted in 2008 and 2009 as a half-season crop. Four-row plots 6.9 m by 0.5 m, were monitored bimonthly for °Brix, height, and sugar accumulation. Yield and extractable sap were taken at the end of season. Stalk yield was greatest for the cultivar Sugar Top (4945 kg ha-1) and lowest for Simon (1054 kg ha-1). Dale ranked highest ethanol output (807 L ha-1) while Simon (123 L ha-1) is the lowest. All cultivars peak Brix accumulation occurs in early October. Individual sugar concentrations indicated sucrose is the predominant sugar with glucose and fructose levels dependent on cultivar. Supplemental ethanol in fermented wort was the best preservative tested to halt degradation of sorghum wort.

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The introduction of hybrid seed in developing countries may be in conflict with the tradition of saving seed for the next planting. This study evaluates 15 sorghum (Sorghum bicolor (L.) Moench) hybrids and their three successive generations in three environments. Under optimum conditions for all 15 genotypes segregating generations yielded as well as the F1 generation. Under moisture stress and late planting, the F2 generation showed inbreeding depression for yield and kernels per panicle. Height, panicle length and test weight were reduced and flowering was hastened for all segregating generations. Kernel weight was not affected by segregation. This study indicates that under optimal conditions it is possible to find a line among segregating generations of sorghum that is superior to its F1 hybrid.

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M.Tech. / Sorghum [Sorghum bicolor (L.)] is classified as a relatively recalcitrant crop due to its poor amenability to in vitro and genetic manipulation. An efficient and reproducible in vitro plant regeneration method is vital for a successful transformation of any crop. Plant regeneration and transformation of eight selected elite sorghum genotypes was studied. Immature zygotic embryos were used as explants and cultured on two different callus induction media. Three genotypes ICSV1111N, SRN39 and P898012 were found to be highly regenerable producing 5.99; 5.1 and 4.74 regenerants per explant respectively on the G2+L-proline callus induction medium. The eight elite sorghum genotypes were co-bombarded with the uidA reporter gene and manA selectable marker gene. Bombarded immature zygotic embryos were selected on G2+L-proline callus induction medium supplemented with mannose as a selective agent. PCR Positive transformants were only obtained from genotype P898012. Furthermore the genotype P898012 was stably transformed with a lower DNA amount of manA minimal transgene. The manA gene presence was confirmed with PCR and southern blot analyses and a transformation efficiency of 0.38% was attained. The fertile transgenic plants displayed simple integration patterns, and the gene was also inherited to the T1 progeny of manA resistant trasnsformants in a Mendelian fashion.

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