Frederik Coenraad Botha

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Sucrose accumulation in developing sugar cane (Saccharum officinarum) is accompanied by a continuous synthesis and cleavage of sucrose in the storage tissues. Despite numerous studies, the factors affecting sucrose accumulation are still poorly understood, and no consistent pattern has emerged which pinpoints certain enzyme activities as important(More)
Sugarcane neutral invertase (SNI) has been partially purified from mature sugarcane stem tissue to remove any potential competing activity. The enzyme is non-glycosylated and exhibits catalytic activity as a monomer, dimer and tetramer, most of the activity elutes as a monomer of native M(r) ca 60 k. The enzyme displays typical hyperbolic saturation(More)
In this study, two PCR-based methodologies were evaluated for potential use in the determination of DNA diversity between 20 commercial sugarcane hybrids and 6 ‘outgroup’ varieties of S. spontaneum, S. officinarum and hybrids from early in the genealogy. The first method involved PCR amplification of sugarcane DNA in the presence of random, decamer primers(More)
Pyrophosphate: fructose 6-phosphate 1-phosphotransferase (PFP) activity was successfully down-regulated in sugarcane using constitutively expressed antisense and untranslatable forms of the sugarcane PFP-β gene. In young internodal tissue activity was reduced by up to 70% while no residual activity could be detected in mature tissues. The transgenic plants(More)
Biochemically, it is not completely understood why or how commercial varieties of sugarcane (Saccharum officinarum) are able to accumulate sucrose in high concentrations. Such concentrations are obtained despite the presence of sucrose synthesis/breakdown cycles (futile cycling) in the culm of the storage parenchyma. Given the complexity of the process,(More)
In this study, UDP-glucose dehydrogenase has been purified to electrophoretic homogeneity from sugarcane (Saccharum spp. hybrid) culm. The enzyme had a pH optimum of 8.4 and a subunit molecular mass of 52 kDa. Specific activity of the final preparation was 2.17 micromol/min/mg protein. Apparent K(m) values of 18.7+/-0.75 and 72.2+/-2.7 microM were(More)
Russian wheat aphid (RWA) infestation, ethylene exposure, and mechanical wounding resulted in differential expression of chitinase (EC isoenzymes in near-isogenic wheat lines susceptible and resistant to the RWA. Isoelectric focusing (IEF) and non-denaturing IEF gels revealed the existence of multiple isoenzymes of chitinase with a wide range of(More)
Gene expression of grapevine vacuolar H+-pyrophosphatase (V-PPase EC during fruit ripening has previously been reported. Here we report on putative multiple V-PPase isoforms in grapevine. In this study a full-length cDNA sequence with an open reading frame of 2,295 nucleotides encoding a V-PPase gene (vpp2: acc. nr. AJ557256) was cloned. Sequence(More)
The isozymes of phosphoglyceromutase from the developing endosperm of Ricinus communis have been partially purified. The purified cytosolic and plastid isozymes have specific activities of 622.8 and 83.8 mumol min-1 mg protein-1, respectively. They both have relative molecular masses of approximately 64,000. The cytosolic enzyme has lower Km values for both(More)
Three sucrose synthase (SuSy) (EC forms were isolated from sugarcane leaf roll tissue. During anion exchange chromatography, one peak of activity (SuSyA) eluted during the wash step and the other peak (SuSyB) during the salt gradient phase at 180mM KCl concentration. A third form of activity (SuSyC), which also eluted at 180mM KCl, was also(More)