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A potato (Solanum tuberosum) cDNA encoding an isoform of disproportionating enzyme (stDPE2) was identified in a functional screen in Escherichia coli. The stDPE2 protein was demonstrated to be present in chloroplasts and to accumulate at times of active starch degradation in potato leaves and tubers. Transgenic potato plants were made in which its presence was almost completely eliminated. It could be demonstrated that starch degradation was repressed in leaves of the transgenic plants but that cold-induced sweetening was not affected in tubers stored at 4degreesC. No evidence could be found for an effect of repression of stDPE2 on starch synthesis. The malto-oligosaccharide content of leaves from the transgenic plants was assessed. It was found that the amounts of malto-oligosaccharides increased in all plants during the dark period and that the transgenic lines accumulated up to 10-fold more than the control. Separation of these malto-oligosaccharides by high-performance anion-exchange chromatography with pulsed-amperometric detection showed that the only one that accumulated in the transgenic plants in comparison with the control was maltose. stDPE2 was purified to apparent homogeneity from potato tuber extracts and could be demonstrated to transfer glucose from maltose to oyster glycogen.

In the present paper we investigated the effect of heterologous expression of a rat liver ketohexokinase in potato (Solanum tuberosum L.) plants with the aim of investigating the role of fructose 1-phosphate in plant metabolism. Plants were generated that contained appreciable activity of ketohexokinase but did not accumulate fructose 1-phosphate. They were, however, characterised by a severe growth retardation and abnormal leaf development. Studies of (14)CO(2) assimilation and metabolism, and of the levels of photosynthetic pigments, revealed that these lines exhibited restricted photosynthesis. Despite this fact, the levels of starch and soluble sugars remained relatively constant. Analysis of intermediates of starch and sucrose biosynthesis revealed large increases in the triose phosphate and fructose 1,6-bisphosphate pools but relatively unaltered levels of inorganic phosphate and 3-phosphoglycerate, and these lines were also characterised by an accumulation of glyceraldehyde. The transformants neither displayed consistent changes in the activities of Calvin cycle enzymes nor in enzymes of sucrose synthesis but displayed a metabolic profile partially reminiscent of that brought about by end-product limitation, but most likely caused by an inhibition of photosynthesis brought about by the accumulation of glyceraldehyde. Analysis of the metabolite contents in lamina and vein fractions of the leaf, and of the enzymes of carbohydrate oxidation indicate that the phloem-enriched veins of ketohexokinase-expressing leaves tend toward hypoxia and indicate a problem of phloem transport.

Während der Entwicklung von Früchten der Tomate (Sorte Micro-Tom) wurde der Kohlenhydrat-Stoffwechsel untersucht. Es wurde ein Unterschied zwischen dem Metabolismus im Perikarp und dem des Plazenta-Gewebes gefunden. Stärke wurde in der Plazenta langsamer abgebaut als im Perikarp, während lösliche Zucker im Perikarp stärker akkumulierten. Die Aktivitäten der glykolytischen Enzyme tendierten zu einem Maximum 40 Tage nach der Blüte. Weiterhin wurde die Expression einiger plastidärer Transporter untersucht. Sowohl der Triosephosphat-Tranporter (TPT) als auch der Glucose-6-phosphat-Transporter wurden am stärksten in grünen Früchten exprimiert, während der Reife nahm die Expression ab. Der ATP/ADP-Transporter wurde während der Fruchtentwicklung nur schwach exprimiert.Es besteht die Hypothese, daß die Rolle der drei Enzyme plastidäre Fructose-1,6-Bisphosphatase (cp-FBPase), ADP-Glucose Pyrophosphorylase (AGPase) und Glucan Wasser Dikinase (GWD) darin besteht, die Stärke-Akkumulation in der frühen Entwicklung der Tomaten-Frucht zu beeinflussen. Diese Hypothese wurde unter Verwendung der Antisense-Technik für die plastidären FBPase (unter der Kontrolle des B33 Promoters), sowie für die AGPase und die GWD (beide unter der Kontrolle des CaMV 35S-Promoters) in der Tomaten-Kultivar Moneymaker untersucht. Die Repression von plastidärer FBPase oder AGPase in der Frucht der Tomate scheint die Metaboliten-Konzentrationen nicht so stark wie in den Blättern zu beeinflussen. Der Grund hierfür ist wahrscheinlich, daß jede Veränderung durch die Fähigkeit der Frucht, Zucker zu importieren, abgepuffert wird. Auf der anderen Seite hatte die Repression des GWD Proteins in der Frucht der Tomate starke Effekte auf die Metaboliten-Konzentrationen., Carbohydrate metabolism was studied during the development of fruits of the tomato cultivar Micro-Tom. The metabolism of the pericarp and placental tissues was found to be different. Starch being degraded more slowly in the placenta than in the pericarp, while soluble sugars accumulated to a greater extent in the pericarp. The activities of glycolytic enzymes tended to peak at 40 days after flowering. The expression of some plastidial transporters was also studied. Both the triose phosphate transporter (TPT) and Glucose-6-Phosphate (Glc-6-P) transporter were expressed greatest in green fruits, before declining. The expression of the triose phosphate transporter (TPT) was greater than that of Glc-6-P transporter. The ATP/ADP transporter was expressed to a low level throughout fruit development. The role of three enzymes Chloroplastic Fructose-1,6-bisphosphatase (cp-FBPase), ADP-glucose Pyrophosphorylase (AGPase) and Glucan Water Dikinase (GWD) protein are thought to influence the accumulation of starch in early development in tomato fruit were studied in normal sized tomatoes of the cultivar Moneymaker using antisense technique under the control of the patatin B33 promoter in the case of cp-FBPase, and the CaMV 35S promoter in the case of AGPase and GWD protein. It appears that repression of cp-FBPase and AGPase in tomato fruits does not influence metabolite levels as greatly as it does in leaves, possibly because any alterations are buffered by the ability of the fruit to import sugars. On the other hand, the repression of GWD protein in tomato fruits has a strong effect on metabolite levels.

The Plant Research Department at Risø National Laboratory has the unique opportunity to be the only life science department located in an environment that is largely dominated by physicists. In 2002 increasing numbers of projects have been initiated thatestablish interdisciplinary research in order to take optimal advantage of the different fields of expertise that are established at Risø National Laboratory. These activities are mainly related to develop novel post-genomic tools to assign function togenes, which are widely applicable in the life sciences. The Plant Research Department applies these and state-of-the-art technologies to increase knowledge to develop crops with improved agronomic traits and to engineer high-value compound containingplants, which are, in addition, able to meet the growth conditions of the future environment with elevated temperatures and increasing carbondioxide and ozone concentrations in the atmosphere. Finally, activities are increasing to establish systems thatoptimize the production of energy from biomass in order to promote sustainability in industrial societies. The department is divided into five research programmes that are linked through their individual expertise delivered to the rest of the department.Three programmes are engaged in improving the agronomic performance of plants. Genetic and molecular genetic tools are developed to enhance the nutrient efficiency of plants, to strengthen the withstanding of plants to fungal attack, or to adapt theflowering time to the optimal use of crops. One programme is devoted to improve the market value of plant products. Plants with enhanced nutritional value or that contain novel renewable resources are designed to add value to the European Agro-Industries.A fifth programme ultimately is studying the effects of the future climate on plant growth, and the performance of newly designed crops and their interaction with the environment. Diverse activities in the area of Functional Genomic

Three growing concerns - sustainability (particularly in the transport sector), security of energy supply and climate change – have combined to increase interest in bioenergy. The trend towards bioenergy has been further encouraged by technologicaladvances in biomass conversion and significant changes in energy markets. We even have a new term, “modern bioenergy”, to cover those areas of bioenergy technology – traditional as well as emerging – which could expand the role of bioenergy. Besides itspotential to be carbon-neutral if produced sustainably, modern bioenergy shows the promise of covering a considerable part of the world’s energy needs, increasing the security of energy supply through the use of indigenous resources, and improving localemployment and land use. To make these promises a reality, however, requires further R&D. This report provides a critical examination of modern bioenergy, and describes current trends in both established and emerging bioenergy technologies. As well asexamining the implications for the global energy scene, the report draws national conclusions for European and Danish energy supply, industry and energy research. The report presents the status of current R&D in biomass resources, supply systems, endproducts and conversion methods. A number of traditional and modern bioenergy technologies are assessed to show their current status, future trends and international R&D plans. Recent studies of emerging bioenergy technologies from internationalorganisations and leading research organisations are reviewed. The report is based on internationally-recognised scientific material, and is fully referenced. The presentation of current global developments in bioenergy is based on the latest informationfrom authoritative sources including the IEA, the World Energy Council (WEC) and World Energy Assessment. This is the second in the series of Risø Energy Reports, which are published to provide global, regional and national perspectiv

Bioenergi er energi, der stammer fra vedvarende kilder af biologisk oprindelse. Normalt bruges energiafgrøder dyrket specielt til formålet, eller biprodukter fra landbrug, skovbrug eller fiskeri. Eksempler på bioenergikilder er træbrændsel, bagasse(udpressede sukkerrør), organisk affald, biogas og bioethanol. Bioenergi er den eneste vedvarende energikilde, der findes i fast, flydende og gasform.

For quantification of alpha-glucan, water dikinase(GWD) activity in crude extracts of plant tissues a radio-labeling assay was established that uses soluble starch and P-33-labeled ATP as phosphate acceptor and donor, respectively. A constant rate of starch labeling was observed only if the ATP applied was labeled at the beta position. In wild-type extracts from leaves of Arabidopsis thaliana (L.) Heynh. the maximum rate of starch phosphorylation was approximately 27 pmol min(-1) (mg protein)(-1). Leaf extracts from the GWD-deficient sex1 mutants of Arabidopsis showed no significant incorporation of phosphate whereas extracts from potato (Solanum tuberosum L.) tuber expressing a GWD antisense construct exhibited less activity than the wild-type control. To our knowledge this is the first time that a quantification of the starch-phosphorylating activity has been achieved in plant crude extracts.