A5103235668- Food composition and properties
- Plant nutrient uptake and metabolism
- Phytase and its Applications
- Microbial Metabolites in Food Biotechnology
- Potato Plant Research
- Plant tissue culture and regeneration
- Photosynthetic Processes and Mechanisms
- Legume Nitrogen Fixing Symbiosis
- Enzyme Production and Characterization
- Copper Interconnects and Reliability
- Sugarcane Cultivation and Processing
- Bacterial Genetics and Biotechnology
- Semiconductor materials and devices
- Cellular transport and secretion
- Biofuel production and bioconversion
- Transgenic Plants and Applications
- Plant Molecular Biology Research
- Semiconductor materials and interfaces
- Electronic Packaging and Soldering Technologies
- Astro and Planetary Science
- Lipid metabolism and biosynthesis
- Plant Stress Responses and Tolerance
- Insect symbiosis and bacterial influences
- Polysaccharides and Plant Cell Walls
- Microbial Metabolic Engineering and Bioproduction
Stellenbosch University
2013-2024
Cornell University
2017-2022
Max Planck Institute of Molecular Plant Physiology
1999-2010
Nordic Laboratory for Luminescence Dating
2004
Max Planck Society
1997-2003
University of Potsdam
2002
John Innes Centre
1996-1998
Westmead Hospital
1998
Biotechnology and Biological Sciences Research Council
1997
Wilmington University
1996
To determine the enzymatic function of starch-related R1 protein it was heterologously expressed in Escherichia coli and purified to apparent homogeneity. Incubation with various phosphate donor acceptor molecules showed that is capable phosphorylating glucosyl residues α-glucans at both C-6 C-3 positions a ratio similar occurring naturally starch. Phosphorylation occurs dikinase-type reaction which three substrates, an α-polyglucan, ATP, H 2 O, are converted into products, α-polyglucan-P,...
Starch is the major storage carbohydrate in higher plants and of considerable importance for human diet numerous technical applications. In addition, starch can be accumulated transiently chloroplasts as a temporary deposit carbohydrates during ongoing photosynthesis. This transitory has to mobilized subsequent dark period. Mutants defective mobilization are characterized by high contents leaves after prolonged periods darkness therefore termed excess (sex) mutants. Here we describe...
A functional screen in Escherichia coli was established to identify potato genes coding for proteins involved transitory starch degradation. One clone isolated had a sequence very similar recently described chloroplast-targeted beta-amylase of Arabidopsis. Expression the gene E. showed that protein product could degrade both granules and solubilized amylopectin, while import experiments demonstrated imported processed into pea chloroplasts. To study function degradation, transgenic plants...
Mutations at the rug5 (rugosus5) locus have been used to elucidate role of major soluble isoform starch synthase II (SSII) in amylopectin synthesis developing pea embryo. The SSII gene maps locus, and one three mutant lines has shown carry a base pair substitution that introduces stop codon into open reading frame. All alleles cause dramatic reduction or loss protein. mutations pleiotropic effects on activities other isoforms but apparently not those enzymes synthesis. These result abnormal...
Abstract Starch is one of the most important products synthesized by plants that used in industrial processes. If it were possible to increase production or modify starches vivo, using combinations either genetically altered mutant plants, may make them cheaper for use industry, open up new markets modified starches. The conversion sucrose starch storage organs is, therefore, discussed. In particular roles different enzymes directly involved synthesizing molecules on altering structure are...
A chimaeric antisense construct was used to reduce the activities of two major starch-synthase isoforms in potato tubers simultaneously. range reductions total were found resulting transgenic plants, up a maximum 90% inhibition. The reduction activity had profound effect on starch granules, which became extremely distorted appearance compared with control lines. Analysis indicated that amounts produced tubers, and amylose content starch, not affected by activity. In order understand why...
Abstract The role of pyrophosphate in primary metabolism is poorly understood. Here, we report on the transient down-regulation plastid-targeted soluble inorganic pyrophosphatase Nicotiana benthamiana source leaves. Physiological and metabolic perturbations were particularly evident chloroplastic central metabolism, which reliant fast efficient dissipation. Plants lacking plastidial (psPPase) characterized by increased levels, decreased starch content, alterations chlorophyll carotenoid...
Cassava (Manihot esculenta Crantz) is a root crop used as foodstuff and starch source in industry. Starch functional properties are influenced by many structural features including the relative amounts of two glucan polymers amylopectin amylose, branched structure amylopectin, granule size presence covalent modifications. phosphorylation, where phosphates linked either to C3 or C6 carbon atoms glucosyl residues, naturally occurring modification known be important for remobilization. The...
The impact of a mutation at the r locus peas ( Pisum sativum L.) on structure starch in leaf has been studied. specifically eliminates A class isoform starch‐branching enzyme (SBE A) from leaf, causing 10‐fold reduction total activity enzyme. Gel‐permeation chromatography and thymol precipitation show that wild‐type consists polymers with general characteristics amylose amylopectin, although is only very minor component starch. High‐performance anion exchange (HPAEC) debranched amylopectin...
A chimaeric antisense construct was used to reduce the activities of two major starch-synthase isoforms in potato tubers simultaneously. range reductions total were found resulting transgenic plants, up a maximum 90% inhibition. The reduction activity had profound effect on starch granules, which became extremely distorted appearance compared with control lines. Analysis indicated that amounts produced tubers, and amylose content starch, not affected by activity. In order understand why...
Abstract A potato (Solanum tuberosum) cDNA encoding an isoform of disproportionating enzyme (stDPE2) was identified in a functional screen Escherichia coli. The stDPE2 protein demonstrated to be present chloroplasts and accumulate at times active starch degradation leaves tubers. Transgenic plants were made which its presence almost completely eliminated. It could that repressed the transgenic but cold-induced sweetening not affected tubers stored 4°C. No evidence found for effect repression...
Carbohydrate metabolism during the development of fruits tomato cultivar Micro‐Tom was studied. The pericarp and placental tissues found to be different. Starch degraded more slowly in placenta comparison with pericarp, whereas soluble sugars accumulated a greater extent pericarp. activities glycolytic enzymes tended peak at 40 days after flowering. Two these, phosphoenolpyruvate phosphatase pyruvate kinase, showed dramatic increase activity just before this peak, possibly indicating role...
Symbiosis involves responses that maintain the plant host and symbiotic partner's genetic program; yet these cues are far from elucidated. Here we describe effects of lumichrome, a flavin identified Rhizobium spp., applied to lotus (Lotus japonicus) tomato (Solanum lycopersicum). Combined transcriptional metabolite analyses suggest both species shared common pathways were altered in response this application under replete, sterile conditions. These included genes involved symbiosis, as well...