Abiotic stresses - drought, salinity or extreme temperatures - cause morphological and physiological changes, affect growth, development and plant productivity. In crops, these limitations often reduce yields up to 50%. Plants have developed various mechanisms ensuring some degree of abiotic stress tolerance, which undoubtedly include changes in carbohydrate metabolism. The nature of many defense mechanisms is not yet fully understood, moreover, most findings were obtained by studying model plants and little is known about their validity in crops. This work was therefore focused on woodland strawberry (Fragaria vesca L.) from economically important family Rosaceae. Controlled conditions and targeted exposure to stress factors was obtained through the cultivation in vitro. Strawberry plants and callus cultures were exposed to various stresses and their combinations, better reflecting the natural conditions. At various stages of stress reaction, growth characteristics, changes in the content and the spectrum of soluble carbohydrates and oxidative stress levels were monitored and compared with plants growing under optimal conditions. Abiotic stress responses of strawberry plants were very inhomogeneous, which complicated the obtaining of statistically significant results. The only significant response...

Plants are exposed to many adverse factors during their life cycles. Abiotic stresses are significantly limiting plant growth and development. Abiotic stress response mechanisms involve compatible solute synthesis (e.g. sugars, sugar alcohols and amino acids). The aim of this study was to characterise the responses of plants from Plantago genus to different abiotic stresses (drought, salinity, cold and stress combination). The complete plants grew under in vitro conditions. I compared morphological parameters, selected metabolic parameters (carbohydrates balance and proline accumulation) under optimal conditions and stress exposure. This study was focused on plants from genus Plantago, because they differ from each other in their tolerance to the salinity. Both, the glycophyte and the halophyte species are described within this genus. Plantains produce besides widespread soluble carbohydrates (sucrose, glucose, fructose) also sugar alcohol sorbitol, which has been reported as a significant component of the stress response. In addition, the reaction of plants to different carbon and energy sources was tested. More severe growth inhibition of the glycophyte Plantago lanceolata compared to the halophyte P. maritima was observed under salt treatment. Significant accumulation of sorbitol was observed...

A turn to more sustainable resources has lead the research during the last decades to algae. Algae is a resource that has been utilized for thousands of years offering a variety of possibilities. Nevertheless modern technology were able to uncover algae’s great potential and pave the way for alternative uses such as biofuel and biomaterial production. Towards that direction, ‘Seafarm’ aims in utilizing algae in the most efficient and sustainable way. For that purpose various steps have been established, including the biorefinery step which entail among other the extraction of carbohydrates from brown algae. The current thesis is based on an extraction of carbohydrates from Saccharina latissima, a brown algae species, which was developed by Viktor Öberg during his master thesis at KTH. The aim of this work is to assist in the scaling up of that laboratory process by analyzing the basic steps and substances of the process, investigating its environmental performance and identifying improvement areas for theoretical optimization. The results of the aforementioned analysis include a substance flow analysis which reveals the basic steps of the process and constitute the basis for further analysis. The second step examines the environmental performance of the process based on the chemical selection. Hence the results are a risk assessment of chemicals with performance indicators for each chemical as well as the whole process. The final part provides a theoretical optimization of the process based on literature studies where the recommendations are divided in production optimization and environmental performance. The above results constitute the basis of the analysis of the process and sets the foundations for scaling up the process at an industrial level. The current analysis in combination with an energy and economic assessment could be used for the designing of the process and its integration in the biorefinery.

<p>Naturally occurring carbohydrates polymers and their functional derivatives play important roles in the research and technology development in the food, nutrition, and pharmaceutical areas. A major property of these polymeric materials is to associate, enable, enhance, and/or deliver small-molecule active compound such as phytochemicals, nutraceuticals, and active pharmaceutical ingredients (APIs). The goal of this project was to synthesize and characterize phytoglycogen-based materials and study their structure-function relationships in association with selected small-molecule active compounds, including resveratrol, a food-related poorly water-soluble phenolic compound, griseofulvin, an insoluble API, and CCVJ (9-(2-carboxy-2-cyanovinyl) julolidine) a molecular rotor used as a structural probe of polymeric materials. </p><p>In this study, phytoglycogen (PG) was derivatives to phytoglycogen octenyl succinate (PG-OS), hydroxypropyl phytoglycogen (HPP), and octenylsuccinate hydroxypropyl phytoglycogen (OHPP). PG, HPP, and OHPP were evaluated for their efficacy in improving the solubility and Caco-2 permeation of resveratrol and griseofulvin, and using CCVJ, PG-OS was evaluated on its performance at oil-water interface in comparison with OSA-starch, acacia gum, and sodium caseinate. The results showed that: 1) PG, HPP, and OHPP substantially improved the soluble amount and Caco-2 monolayer permeation of resveratrol and griseofulvin, and anti-fungal efficacy of griseofulvin in the aqueous system were significantly enhanced; suggesting that the active ingredients were effective solubilized and released to become bioavailable, 2) among all PG-based biopolymers, OHPP showed superior performance in solubilizing resveratrol and griseofulvin, and 3) in the oil-water two-layer model system, PG-OS, OSA-starch, acacia gum, and sodium caseinate all affected the transferring of CCVJ from oil to aqueous phase, and the effect was monitored and interpreted by the emission spectra of molecular rotor; in the emulsion system, the emission peak wavelength of CCVJ was correlated with the amount of biopolymer adsorbed at the interface of emulsion droplets, and the molecular rotor-based method can be used to characterize the interfacial adsorption of biopolymer at the interface in oil-in-water emulsion.</p><p>This study provides information on the interactions between phytoglycogen-based biopolymers and poorly water-soluble active ingredients, and may potentially supports the study of new functional ingredients interaction with phytoglycogen-based biopolymers in aqueous system. Furthermore, this work allowed us to advance the use of molecular rotor as new analytical tool to study the physicochemical properties of biopolymer.</p>

Chickpea (Cicer arietinum) is an important legume crop globally ranked third after dry bean (Phaseolus vulgaris) and field pea (Pisum sativum). It constitutes 20% of the total global pulse production and around 95% of its production and consumption takes place in developing countries. Major constraints to chickpea production in sub Saharan Africa (SSA) have broadly been related to abiotic stresses, particularly drought and heat stresses, predicted to increase due to the global climatic changes.Dueto the imperativeness of research for identifying heat tolerance markers for potential chickpea genotype selection, in chapter two of the thesis, the response of four chickpea genotypes to a natural temperature gradient in the field was assessed using chlorophyll fluorescence, non-structural carbohydrate, gas exchange and grain yield. Field experiments were carried out in two winter seasons at three locations with known differences in temperature in NE South Africa. Results showed two genotypes (Acc#3 and Acc#7) were tolerant to heat stress with an Fᵥ/Fₘ of 0.83-0.85 at the warmer site, while the two sensitive genotypes (Acc#RR-2 and Acc#8) showed lower Fᵥ/Fₘ of 0.78-0.80. Both chlorophyll fluorescence measurements: dark-adapted Fᵥ/Fₘ and Fq'/Fₘ' (where Fq' =Fₘ'–F) measured at comparable high light levels correlated positively with grain yield. The two tolerant genotypes also showed higher photosynthetic rates,starch, sucrose and grain yield than the sensitive genotypes at the warmer site. However, these parameters were consistently higher at the cooler than at the warmer sites. It was concluded that genotypes Acc#RR-3 and Acc#7 are heat tolerant and chlorophyll fluorescence and leaf carbohydrates are suitable tools for selection of heat tolerant chickpea genotypes under field conditions. The coolest site of Polokwane showed favourable conditions for chickpea production.Heat and drought stresses are two abioticfactors that often occur simultaneously and are predicted to increase, consequently hampering plant growth. Response of different species to either stresses is well documented but information on the response of the same genotypes to both stresses in chickpea is limited. We aimed to determine whether previously noted heat stress tolerant genotype (Acc#7) is drought tolerant and the heat sensitive (Acc#8) is drought sensitive, and whether intermittent moisture supply at vegetative stage would induce priming effect to later drought at flowering. At vegetative stage, plants were divided into three groups, non-stressed (watered to 75% field capacity (FC), severe water stress (moisture-withholding for 14 days) and treated to 40% FC throughout the experiment (mild-stress), with recovery for the severely stressed plants after which they were stressed (double-stress) at flowering. Drought treatments at vegetative and flowering growth stages decreased physiological parameters and biomass accumulation in both genotypesexcept low water supply at 40% FC that decreased biomass in Acc#7 but not Acc#8. Double drought stress resulted in priming effect in Acc#7, having higher biomass, chlorophyll fluorescence, stomatal conductance, net photosynthesis, and relative water content in comparison to the introduction of stress only at flowering growth stage, as well as in comparison to Acc#8. These results showed that both Acc#7 and Acc#8 are sensitive to drought whereas after priming Acc#7 is better acclimated to drought than Acc#8 associated with osmotic adjustment on leaf relative water content (RWC) and higher capacity to protect photosynthetic activity, making Acc#7 potentially ideal for areas associated with intermittent drought spells. This observation, however, disapproved the hypothesis that Acc#7 is more drought tolerant than Acc#8 but is rather better acclimated than Acc#8, because of its superiority only in primed plants and not those stressed only at either vegetative or flowering stages. The findings emphasise the importance of matching chickpea physiological performance to expected rainfall amounts and distribution in drought prone areas during genotype selection. Chapter four of the thesis was an interrogative proteome analysis of the differences in the heat tolerant and sensitive chickpea (Cicer arietinumL.; Fabaceae) genotypes along a temperature gradient under field conditions which will help in identifying the molecular mechanisms involved in the crop's tolerance. Few studies have thus far combined chickpea physiological and proteome analysis to elucidate the changes in abundance and/or activity of relevant enzymes and expression of heat responsive proteins. In this study, analyses of chlorophyll concentrations, gas exchange, flavonoids and anthocyanin concentrations from a chamber experiment, as well as proteomic parameters from field studies in both the heat tolerant and sensitive genotypes are presented. The heat tolerant genotype Acc#7 maintained unaltered physiological performance at flowering growth stage when exposed to high (35/30°C) and moderate (30/25°C) heat stress, under climate chamber conditions compared to the two heat susceptible genotypes (Acc#RR-2 and Acc#8). Results from the proteomic studies showed an up-regulation in proteins related to protein synthesis (e.g. ribulose bisphosphate carboxylase/oxygenase activase), intracellular traffic (e.g. mitochondrial dicarboxylate/tricarboxylate transporter DTC), defence (e.g. HSP70) and transport (e.g. GTP-binding protein SAR1A-like) in heat tolerant Acc#7 compared to the susceptible Acc#8. Results from KEGG analyses support the involvement of probable sucrose-phosphate synthase and sucrose-phosphate phosphatase proteins in the starch and sucrose pathway,that were up-regulated in the heat tolerant genotype Acc#7. This result was in support of our earlier report where tolerant genotype Acc#7 had higher leaf starch and sucrose concentrations in comparison to the susceptible genotype Acc#8. The presence of these differentially regulated proteins including HSP70, ribulose bisphosphate carboxylase/oxygenase activase, plastocyanin and protoporphyrinogen oxidase shows their potential role in field grown chickpea tolerance to heat stress at flowering growth stage. In conclusion, chlorophyll fluorescence (both Fᵥ/Fₘ and Fq'/Fₘ') and leaf carbohydrates were identified as selection markers that can potentially be used for chickpea phenotyping for heat stress under field conditions with the chlorophyll fluorescence parameters correlating positively with seed yield. Due to its higher biomass, chlorophyll fluorescence (Fᵥ/Fₘ), stomatal conductance, net photosynthesis and RWC, heat tolerant genotype Acc#7 was identified to have better adaptive tolerance to drought stress after priming through exposure to intermittent dry spells than Acc#8. Furthermore, under controlled climate chamber conditions, Acc#7 consistently showed characteristics of tolerance to heat stress while Acc#RR-2 and Acc#8 were heat susceptible. Higher chlorophyll fluorescence, grain yield, chlorophyll concentrations, gas exchange, flavonoids and anthocyanin concentrations for Acc#7 compared to Acc#8 in the climate chamber was further validated by the higher up-regulation of proteins involved in protein synthesis, intracellular traffic, defence and transport in Acc#7 compared to Acc#8. The incorporation of proteomics in heat and drought stress studies will potentially help further the understanding of mechanisms by which the crop responds to these stresses.

Dynamic Combinatorial Chemistry (DCC) is a recently introduced supramolecular approach to generate dynamically interchanging libraries of compounds. These libraries are made of different building blocks that reversibly interact with one another and spontaneously assemble to encompass all possible combinations. If a target molecule, for instance a receptor is added to the system and one or more molecules show affinity to the target species, these compounds will, according to Le Châtelier´s principle, be amplified on the expense of the other non-bonding constituents. To date, only a handful of different systems and formats have been used. Hence, to further advance the technique, especially when biological systems are targeted, new reaction types and new screening methods are necessary. This thesis describes the development of reversible sulfur reactions, thiol/disulfide interchange and transthiolesterification (the latter being a new reaction type for DCC), as means of generating reversible covalent bond reactions. Two different types of target proteins are used, enzymes belonging to the hydrolase family and the plant lectin Concanavalin A. Furthermore, two new screening/analysis methods not previously used in DCC are also presented; the quartz crystal microbalance (QCM)-technique and catalytic self-screening. / QC 20101118

Bacterial biofilms represent a challenge to the healthcare system because of their resilience against antimicrobials and immune attack. Biofilms consist of bacterial aggregates embedded in an extracellular polymeric substance (EPS) composed of polysaccharides, nucleic acids and proteins. We hypothesised that carbohydrates could contribute to immune recognition of Pseudomonas aeruginosa biofilms by engaging C-type lectins. Here we show binding of Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin (DC-SIGN, CD209), mannose receptor (MR, CD206) and Dectin-2 to P. aeruginosa biofilms. We also demonstrate that DC-SIGN, unlike MR and Dectin-2, recognises planktonic P. aeruginosa cultures and this interaction depends on the presence of the common polysaccharide antigen. Within biofilms DC-SIGN, Dectin-2 and MR ligands appear as discrete clusters with dispersed DC-SIGN ligands also found among bacterial aggregates. DC-SIGN, MR and Dectin-2 bind to carbohydrates purified from P. aeruginosa biofilms, particularly the high molecular weight fraction (HMW; >132,000 Da), with Ks in the nM range. These HMW carbohydrates contain 74.9-80.9% mannose, display α-mannan segments, interfere with the endocytic activity of cell-associated DC-SIGN and MR and inhibit Dectin-2-mediated cellular activation. In addition, biofilm carbohydrates reduce the association of the DC-SIGN ligand Lewis, but not fucose, to human monocyte-derived dendritic cells (moDCs), and alter moDC morphology without affecting early cytokine production in response to lipopolysaccharide or P. aeruginosa cultures. This work identifies the presence of ligands for three important C-type lectins within P. aeruginosa biofilm structures and purified biofilm carbohydrates and highlights the potential for these receptors to impact immunity to P. aeruginosa infection.

Oligosaccharides play very crucial biological roles in the human body. They are structurally diverse and very challenging to analyze. In an attempt to contribute towards the analysis of oligosaccharides in the growing filed of 'Glycomics', we explored different ways to make novel efficient oligosaccharide tags to label N -linked oligosaccharides from glycoproteins. We synthesized and characterized various oligosaccharide tags which are useful to analyze the oligosaccharide by mass spectrometry, HPLC, and bioaffinity. In these tags we incorporated ar UV/fluorescent core, a biotin moiety and an amino/azido/alkyne terminus. We varied the structures of the tags for improved solubility in common organic solvents. These tags were used to label standard oligosaccharides, and the labeling efficiency was evaluated.

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