Research Els Prinsen

Abstract

How do animals, including humans, and plants cope with stress under altered environmental conditions (e.g., warming, drought), or in the presence of specific contaminants (e.g. PFAS, pesticides) originating from a variety of diverse sources? These are our main running research questions. In this biological/environmental research, it is crucial to trace and quantify different compounds of interest in a broad range of samples ranging from water, soil, and sediments over animal/human- and plant tissues. On the one hand, compounds of interest are hormones, which are well-known signal molecules altered in organisms during stress and being active in a very low concentration range. On the other hand, the ecotoxicological applications require research that keeps pace with the dynamic changes in the new generation of molecules used in industry and the evolution towards raised restriction levels in the environment determined by EU and local governments. Therefore, to claim a worldwide leading position in this field, it is important that we invest in the development of innovative sensitive analytical techniques which allow us to trace and quantify extremely low amounts of different compounds of interest. This project application aims to purchase a sustainable, new generation UPLC-TQD-MS, to improve the analytical platform available. This opportunity will not only support ongoing joint collaborations but will also bring the UAntwerpen to an acknowledged leading position in this field.

Researcher(s)

• Promoter: Prinsen Els
• Co-promoter: Bervoets Lieven
• Co-promoter: Covaci Adrian
• Co-promoter: Eens Marcel
• Co-promoter: Groffen Thimo

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

The common denominator of the European Duckweed Network is duckweed or Lemnaceae. These small aquatic plants are not only the world's fastest growing flowering plants, they can produce a substantial amount of protein per hectare, considerably in excess of conventional protein crops. Furthermore, they take up nutrients, heavy metals, and nuclear contaminations from heavy polluted wastewater. These are all traits that make duckweed highly suitable to tackle European and global challenges such as food and feed production, bioremediation, or even combinations of both. Thus, duckweed can be a key part of a circular solution to the current sustainability crisis, for example by growing duckweed on pig manure waste, and subsequently using it as pig feed. The European Duckweed Network brings together key research experts from diverse fields such as agriculture, genomics, physiology, space research and nuclear science, and allows knowledge transfer on pilot and large-scale research on duckweed cultivation. Despite the differences in background, all network partners share a common aim, to develop duckweed cultivation for a more sustainable future. It is also recognized by the partners that open communication and knowledge exchange is necessary to achieve this. This way, common challenges such as optimizing harvesting techniques, improved crop protection (against algae, black water lily aphids, and pythium), and reduced plant stress (nutrient imbalances, and climatic conditions) can be systematically tackled, optimally using the multidisciplinary expertise that is present in the network.

Researcher(s)

• Promoter: Asard Han
• Co-promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Per- and polyfluoroalkyl substances (PFAS) are synthetic organic compounds that have unique properties which have led to a widespread industrial and commercial use, and subsequent contamination of the environment. The partitioning of PFAS to the abiotic matrices, which are important exposure routes for PFAS in the food chain, depends on chemical-, media- and site-specific characteristics. Organisms residing in polluted ecosystems may accumulate different PFAS depending on their physiological and structural characteristics, and on the bioavailability of PFAS (affected by among others their chemical structure). Quantitative measurements of bioaccumulation are well known for legacy PFAS, but not for the vast majority. Similarly, the relative lack of toxicological data for most PFAS is an uncertainty factor in ecological risk assessment (ERA). The objective of this study is to investigate how the chemical structure of PFAS affect their bioaccumulation and toxicity in aquatic and terrestrial organisms. We will use a focused comparative testing (i.e. including PFOS and PFOA, for which such information on bioaccumulation and toxicity is present), in a phylogenetically broad range of organisms to provide baseline data for ERA. A probabilistic risk assessment approach using species sensitivity distributions will be used to investigate the chronic and acute toxicity of fifteen PFAS and to estimate toxicity benchmark concentrations for soil, sediment, and freshwater.

Researcher(s)

• Promoter: Bervoets Lieven
• Co-promoter: Prinsen Els
• Fellow: Groffen Thimo

Research team(s)

• Ecosphere

Project type(s)

• Research Project

Abstract

Per- and polyfluoroalkyl substances (PFAS) are chemicals globally present in the environment and biota, as a result of their massive production and use in numerous applications, such as food contact paper, fire-fighting foams, textiles, construction and cleaning products. Their bioaccumulative and persistent properties have led to global regulatory measures for PFOS and PFOA. These are the most frequently detected legacy PFAS and their concentrations are still very high in the environment and biota. In addition, there are many emerging PFAS alternatives developed, with similar structures and chemical properties, not yet regulated and hence used unrestrictedly. However, very little or no information is available on the bioavailability, biomagnification and toxic effects of these emerging compounds, particularly for the terrestrial environment. PFAS may thus accumulate in the environment, posing risks to organisms. There are also many uncertainties on which factors might influence the bioavailability and biomagnification, especially of emerging PFAS. The identification of emerging PFAS, which have largely replaced the legacy PFAS, would allow us to investigate the environmental relevance of currently-used PFAS, as well as to characterize possible point sources. Detailed field studies on soil, plants, invertebrates (e.g. earthworms, woodlice, caterpillars, snails, slugs, and spiders), and great tits (Parus major; a songbird model species) planned in this project will provide us with: 1) an overview of the distribution of legacy and emerging PFAS present in the terrestrial environment near a fluorochemical polluting hotspot in Antwerp, 2) how the concentrations in the food chain are influenced by soil properties, and 3) their potential toxicity in key model species. In addition, experimental lab studies with PFAS and elevated temperature (T) as stressors on terrestrial invertebrates and plants will be performed to: 4) disentangle causal links from confounding effects regarding the soil properties, 5) verify whether or not increased T and PFAS have an additive toxic effect when combined, and 6) create a mechanistic framework explaining the underlying subcellular basis of root growth responses towards PFAS/increased T in the plant model species Arabidopsis thaliana. This project will allow us to understand the bioavailability and mechanism of the toxicity of emerging and legacy PFAS in plants, invertebrates, and birds and will offer instruments for regulators to assess the environmental risk and potential effects on human health.

Researcher(s)

• Promoter: Bervoets Lieven
• Co-promoter: Covaci Adrian
• Co-promoter: Eens Marcel
• Co-promoter: Prinsen Els
• Co-promoter: Vissenberg Kris

Research team(s)

• Ecosphere

Project type(s)

• Research Project

Abstract

A major challenge in sustainable agriculture is to secure crop productivity under adverse environmental conditions in order to match the growing world population. Plants are exposed to multiple abiotic stresses such as submergence – an increasing problem due to global climate change – and cadmium accumulation in soils, resulting in important crop losses. The phytohormone ethylene is known to be a crucial player in stress control. Apart from being the direct precursor of ethylene, the non-proteinogenic three-membered ring alpha-amino acid ACC, occurs as different metabolites in planta and acts as a signaling molecule independent of ethylene. This project aims to unravel how and under which form ACC regulates normal plant growth and the responses to flooding and heavy metal stress.

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Following the nuclear accidents in the Chernobyl (1986) and Fukushima Dai-Ichi (2011) nuclear power plants, vast areas of land were contaminated with radionuclides, leading to a long-term exposure of the environment to enhanced levels of ionizing radiation. In the forests near the Chernobyl reactor, some of the Scots pine trees (Pinus sylvestris) that received a sub-lethal dose of radiation began to portray morphological changes resembling those seen when a plant loses its apical dominance, i.e. growth of the pine trees from two or more emerging branches instead of growing along a single primary trunk as usual. Similar abnormal growth patters were recently observed in young Japanese red pine (Pinus densiflora) in the Fukushima Exclusion Zone. The mechanisms behind the radiation-induced morphological abnormalities in these plants has up to date not been elucidated. However, it is known that plant hormones, specifically cytokinins and auxins, play important roles in cell division and cell differentiation during growth of the plant apex, thereby dictating the plant's growth habit. More recently, a strong correlation has been observed between auxin accumulation and DNA methylation. There is also evidence that radiation can induce changes to DNA methylation in plants. In light of these findings, we suggest that radiation leads to a disturbed hormone balance or transport which in turn leads to morphological changes in Pinus sylvestris. It is also proposed that changes to DNA methylation may lie at the basis of the disturbance of the plant hormone metabolism. In collaboration with the Belgian Nuclear Research Centre, these hypotheses will be investigated by providing answers to the following research question: 1. To what extent do the hormone balances contribute to the changed phenotype observed in P. sylvestris after exposure to ionizing radiation? 2. How do the proteome and the transcriptome of P. sylvestris respond after exposure to ionizing radiation 3. Do changes in DNA methylation or in the activity of transposable elements contribute to the observed responses in P. sylvestris? Taken together, the findings obtained during this PhD project can shed light on the abnormal growth patterns seen in irradiated pine trees, thereby giving fundamental insight on the effects of radiation on plant growth.

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Per- and polyfluoralkylated substances or PFAS, which have been used in large quantities since the 1940s because of their applications such as food packaging, are receiving increasing attention since the early 2000s. The production and use of PFAS have led to the global detection in the environment. Despite regulatory measures for perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), the most frequently detected PFAS, there are concerns on many other PFAS that are similar in structure and properties and that are not regulated. Soils form the basis of the terrestrial food chain and PFAS uptake from contaminated soils is known to cause human exposure to PFAS. However, there are many uncertainties on the behaviour of PFAS in soils and the following bioavailability to and bioaccumulation in biota. The general objective of my project is to investigate the role of soil properties and temperature on the uptake and distribution of PFAS in the terrestrial food chain. Descriptive studies, close to a fluorochemical plant, will provide us with an overview of the concentrations of legacy, novel and unknown PFAS in the terrestrial food chain and how these concentrations are influenced by soil properties. In addition, experimental studies will be performed to disentangle causal links from confounding effects, but also to study the uptake and effects in terrestrial invertebrates and plants. This study will help policy makers to set new, or alter existing, PFAS criteria for soil.

Researcher(s)

• Promoter: Bervoets Lieven
• Co-promoter: Eens Marcel
• Co-promoter: Prinsen Els
• Fellow: Groffen Thimo

Research team(s)

• Ecosphere

Project type(s)

• Research Project

Abstract

The equipment applied for in this application is the Tecan SPARK®, a multimode microplate reader. The instrument reads microtiter plates up to 384 wells in various modes. Equipped with several monochromators, it measures optical density, several fluorescence modes and luminescence. It has an incubator-shaker ranging from 18° to 42°C. Unlike many other readers on the market, it is capable of measuring the quality and quantity of nucleic acids and proteins in volumes down to 2 microliters on 16 samples in parallel. It is a modular system which allows future extension with flash injectors, plate stacker, automatic lid removal etc… Prof. L. Bervoets (promotor), prof. G. De Boeck, and prof. H. Svardal (co-promotors) work in the SPHERE group on the effects of environmental stressors, both natural and anthropogenic, on the performance of aquatic and terrestrial organisms, in vivo and in vitro with an emphasis on mechanisms and ecological relevance. Prof. E. Prinsen (co-promotor) and the IMPRES group study plant stress and energy metabolism, acclimation mechanisms and the modelling of Leaf growth and tip growth and the role of plant hormones therein. All team members have an increasing need of in vitro assays to determine enzymatic activity and several other biomarkers such as hormones and cellular metabolites. The advanced possibilities of the SPARK® instrument offer several advantages, e.g. fluorescence modes, luminescence, scanning mode, etc., compared to the groups' current instruments (>10 years old). Notably, the cooling capacity of the incubator is unique on the market today. The facility for cooling is very important for the groups' research: SPHERE mainly focusses on the aquatic environment, and IMPRES on plants in a temperate climate, hence it is necessary to run assays at temperatures lower than typical room.

Researcher(s)

• Promoter: Bervoets Lieven
• Co-promoter: De Boeck Gudrun
• Co-promoter: Prinsen Els
• Co-promoter: Svardal Hannes

Research team(s)

Project website

Project type(s)

• Research Project

Abstract

This research project aims at developing new neutraceuticals to be used as food or feed supplements for human and veterinary use. This research has a dual aim: i) the identification and characteisation of active biomolecules in a fermented plant protein (Lianol®), and ii) the validation of the analytical methods and biomarkers to define the biological activities of these active molecule(s).

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

in this project we will study the effects of UV-B exposure on differential growth in the model plant Arabidopsis. We will investigate whether the UVB light gradient leads to a functional gradient, that eventually controls flavonoid accumulation and control hormonal responses and differential elongation. Molecular physiological, genetic and biochemical methods will be used.

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

This project represents a research agreement between the UA and on the onther hand IWT. UA provides IWT research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

• Promoter: Prinsen Els
• Fellow: Jhaveri Ashka

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

This is a fundamental research project financed by the Research Foundation - Flanders (FWO). The project was subsidized after selection by the FWO-expert panel.

Researcher(s)

• Promoter: Prinsen Els
• Fellow: Van Elst Daan

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Developmental processes involve a complex network of interactions between multiple regulatory processes that traditionally are studied separately. We propose a systems biology approach, whereby experimental biologists closely interact with mathematical modellers, to unravel the functional relationships between auxin signalling, cell division and expansion and whole leaf morphogenesis.

Researcher(s)

• Promoter: Beemster Gerrit
• Co-promoter: Broeckhove Jan
• Co-promoter: Prinsen Els
• Co-promoter: Vanroose Wim
• Co-promoter: Vissenberg Kris

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

This is a fundamental research project financed by the Research Foundation - Flanders (FWO). The project was subsidized after selection by the FWO-expert panel.

Researcher(s)

• Promoter: Prinsen Els
• Fellow: Van Elst Daan

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

The main aim of the project is to advance our knowledge in the evolution and function of bacterial leaf symbiosis within Rubiaceae by addressing the following questions: 1. When and how did bacterial leaf symbiosis originate in different Rubiaceae genera? 2. How strict is the congruence between the phylogeny of host plants and their endosymbionts? 3. At what level and through which mechanisms do bacterial leaf symbionts provide advantages to plants or vise versa?

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Plant growth and development have a direct impact on the balances and productivity of natural and agrarian ecosystems. The morphology of a plant, which can be influenced by biotic as well as by abiotic environmental factors, plays a determining role in plant growth and development. Chronical and ecologically relevant doses UV-B irradiation have an influence on the development and the morphology of the model organism Arabidopsis. The question concerning the underlying mechanism behind this phenomenon, is the central theme of this project.

Researcher(s)

• Promoter: Guisez Yves
• Co-promoter: Prinsen Els
• Fellow: Hectors Kathleen

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Prinsen Els
• Fellow: Van Elst Daan

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

A lot of physiological processes are carried out by protein complexes. Complex formation between cyclin dependent kinases with varying regulatory cyclins is considered the major driving forces of the cell cycle. The formation and activity of such complexes is strongly regulated by different parameters such as the participating components, phosphorylation/dephosphorylation events, interaction with inhibitory (eg. KIP-related protein) and activating (CDK subunit protein) proteins. Complementary to genomical data, achieved by cDNA-AFLP and microarrays, a proteome technical analysis of these cell cycle related complexes is necessary that can give information about the dynamical changes of their activity and structure.The goal of this study is to optimise a bioanalytical method for the purification and isolation of protein complexes in order to study their dynamics during the cell cycle. This can reveal new complexes or constituents, active during a certain phase of the cell cycle. As model species, the highly synchronisable Nicotiana tabacum cv. Bright Yellow-2 (BY-2) or an Arabidopsis thaliana cell suspension culture is used. Samples from different phases are ground in liquid nitrogen or sonicated, and a fraction of a whole cell lysate is subjected to non-denaturing `Blue native polyacrylamide gelelectrophoresis (BN-PAGE)'(Schägger et al., 1991). In this first dimension, protein complexes are separated on the basis of their size. To exclude co-migration of several complexes, a second native dimension (ionexchange 'FPLC) will be incorporated. Samples are subsequently subjected to a denaturing second dimension, SDS-PAGE, in which the complexes will break up into their constituents. With this strategy, the dynamics of the complexes can by followed accurately during their progression through the cell cycle. Together with the TAP-technology group of dr. Geert De Jaeger, the cell cycle interactome will be studied and this can reveal new players during the cell cycle. Post-translational modifications like phosphorylation and glycosylation are important for the activity, stability and formation of protein complexes and will be studied.Identification of protein complexes with changes in abundancy or/and modifications is done by mass spectromectric analysis.

Researcher(s)

• Promoter: Prinsen Els
• Fellow: Remmerie Noor

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Guisez Yves
• Co-promoter: Jansen Marcel
• Co-promoter: Prinsen Els
• Fellow: Hectors Kathleen

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

The project's main objective is "To gain a fundamental insight in the cryo-physiology through a proteome study of banana meristems". It aims to contribute to a more fundamental knowledge of some of the physiological processes that underlie adaptation and acclimatization, as weIl as the mechanisms of stress injury. Many of these stress parameters are correlated. For example, water stress is often associated with salt stress in the root and/or heath stress in the leaves. Resistance towards freezing is highly dependent upon resistance towards tissue dehydration. Plants also often exhibit a cross- resistance what implies that the underlying mechanisms for resistance against different stress factors have common characteristics. These mechanisms are complex and their unraveling can only take place through long term and multidisciplinary research.

Researcher(s)

• Promoter: Prinsen Els
• Promoter: Van Onckelen Harry
• Co-promoter: Laukens Kris
• Co-promoter: Witters Erwin

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

This research project combines the expertise and analytical infrastructure available in two different research laboratories. The main aim of the consortium is replacing the old GC-MS infrastructure by a new generation GC-MS/MS instrument, enabling further identification. This infrastructure will be used for developing new methods for the identification and analysis of stress-related components, with a potential use as markers for stress. At the scientific level, the research domains are strictly separated ((1) stress response in plants and (2) oxidative stress in chronical diseases), however, the stress response and the methodology are in common.

Researcher(s)

• Promoter: Prinsen Els
• Co-promoter: Manuel Y Keenoy Begona

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

This project aims the study of the effects of a range of abiotic factors (level of mineral nutrition and water) as well as inoculation of plants with cytokinin producing microorganisms on dynamics of cytokinin content and metabolism in plants. We plan to test a hypothesis that (1) long-term effect of unfavorable environment leads to a deficit in cytokinins limiting growth of plants when they return to optimal conditions and that (2) inoculation of plants, which have experienced detrimental effect of the environment, with cytokinin producing microorganisms might compensate this deficit of cytokinins and in this way to accelerate growth and increase productivity of plants.

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Microorganisms present in the rhizosphere secrete phytohormones. Although plants synthesize their own phytohormones, also phytohormones present in the rhizosphere penetrate into the plant. In this research project, we will analyze a Bacillus subtilis strain, characterized to be a high cytokinin producer. This rhizosphere bacterium induces growth and development of the plant as well as increases the plant's resistance toward drought, heavy metals and infection diseases.

Researcher(s)

• Promoter: Prinsen Els
• Fellow: Arkhipova Tatyana

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Prinsen Els
• Promoter: Van Onckelen Harry
• Promoter: Vissenberg Kris

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

In the present study, we propose a detailed analysis of the function of the Arabido~is PPR-Iike 1 protein. Our preliminary data indicate that this protein might operate as an integrator of multiple pathways. The PPR-Iike1 gene encodes a pentatricopeptide repeat (PPR) protein. The PPR motif has recently been described and found to be occurring in one of the largest Arabido~is gene families (Small and Peeters, 2000). So far, very little is known about the function of this motif, but it is clearly related to the widespread TPR (tetratricopeptide repeat) protein-binding motif. The latter is present in the SPY protein, a negative regulator of gibberellin action in Arabido~is, and has recently been shown to participate in protein-protein interactions essential for the proper functioning of SPY (Tseng etal. , 2001; Izhaki et al. , 2001 ). Like TPR, the PPR motif is predicted to consist of two a-helices and thereby may have protein-binding propel1ies. To date, several PPR-containing genes have been cloned, and all these PPR proteins were found to be targeted into either the mitochondria or the chloroplasts. Their function appears rather diverse. For instance, Arabidopsis HCF152 is involved In processing of chloroplast psbB-psbT -psbH-petB-petD RNAs as a homodimer with RNA- binding properties (Meierhoff et al., 2003; Nakamura et al., 2003). Likewise, maize CRP1, is involved in chloroplast petD RNA processing and petD and petA translation (Fisk et al., 1999). Petunia Rf is mitochondrially targeted and capable of restoring fertility to cytoplasmic male-sterile plants (Bentolila et al., 2002). Two radish male fertility restorer genes Orf687 and Rfo also encode PPR proteins (Koizuka et al., 2003; Brown et al., 2003). Because of the prevalence of the huge number of different PPR genes in Arabidopsis genome, one can hypothesize that the functions of these PPR proteins could be rather divergent.

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

This project envisages identifying components of the signal transduction cascades during oxidative stress in plants by means of an integrated immunological and proteomic approach. During its development a plant is continuously exposed to various kinds of stress. Its ability to react to these changes in a fast and appropriate manner is essential for its survival. Very often, changes in hormone homeostasis play an important role. Our knowledge regarding the role of plant growth regulators such abscisic acid (ABA), ethylene, jasmonic acid (JA) and salicylic acid (SA) as important signal molecules in stress responses is already substantial. Stress induced auxin and cytokinin action has been described in a restricted set of stress phenomena. Various studies point to oxidative stress as a central component in many cellular responses (Desikan et al., 2001; Neill et al., 2002). Oxidative stress results from an imbalance in the production and metabolism of reactive oxygen species (ROS). ROS are produced as a response to exposure to biotic and abiotic stress and act as a signal that triggers a variety of molecular, biochemical and physiological events. Nitrogen monoxide (NO) is very often an important component in the underlying signal transduction cascades. NO, a gaseous free radical, can interact with ROS in a number of ways and as such influences the response to biotic and abiotic stress factors (Delledonne et al., 1998; Neill et al., 2002; Neill et al., 2003). As is the case in animal models, cyclic GMP and cyclic ADPR are put forward as signal molecules in the plant NO signal transduction system. Cyclic GMP is produced in plants as a response to NO application (Pfeiffer et al., 1994) and in turn cADPR synthesis is thought to be induced by cGMP. Both have been shown to mimic certain functions of NO (Durner et al., 1998), and a specific inhibitor of guanylyl cyclase (ODQ) inhibits Arabidopsis thaliana NO-induced cell death. A membrane permeable cGMP-analog, 8-Br-cGMP, eliminates this inhibitory effect (Clarke et al., 2000). In animal systems, stress induced cADPR synthesis is activated via cGMP-dependent protein kinase. Until now, the existence of such a protein in higher plants has not been reported yet. The recent isolation of the gene for a putative cyclic nucleotide dependent protein kinase in our lab is a convincing candidate for this function. In its promoter region a considerable number of stress-regulated elements are found, such as the ABA-response element (ABRE), the "heat shock"-response element, the ABRE related "GC-repeat" (Litis et al., 1992) and the cold and water stress regulated dehydration (DRE)/"C-repeat"-response elements (Baker et al., 1994). The additional presence of a salicylic acid regulated promoter element (TCA), a wound induced response element, (WUN) (Pastuglia et al., 1997), and of the "TC-rich repeat", a stress and defence induced response element (Klotz en Lagrimini 1996), strengthens our proposition for a stress related function of this putative cyclic nucleotide dependent protein kinase.

Researcher(s)

• Promoter: Prinsen Els
• Promoter: Van Onckelen Harry
• Co-promoter: Laukens Kris
• Co-promoter: Roef Luc
• Co-promoter: Witters Erwin

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

A lot of physiological processes are carried out by protein complexes. Complex formation between cyclin dependent kinases with varying regulatory cyclins is considered the major driving forces of the cell cycle. The formation and activity of such complexes is strongly regulated by different parameters such as the participating components, phosphorylation/dephosphorylation events, interaction with inhibitory (eg. KIP-related protein) and activating (CDK subunit protein) proteins. Complementary to genomical data, achieved by cDNA-AFLP and microarrays, a proteome technical analysis of these cell cycle related complexes is necessary that can give information about the dynamical changes of their activity and structure.The goal of this study is to optimise a bioanalytical method for the purification and isolation of protein complexes in order to study their dynamics during the cell cycle. This can reveal new complexes or constituents, active during a certain phase of the cell cycle. As model species, the highly synchronisable Nicotiana tabacum cv. Bright Yellow-2 (BY-2) or an Arabidopsis thaliana cell suspension culture is used. Samples from different phases are ground in liquid nitrogen or sonicated, and a fraction of a whole cell lysate is subjected to non-denaturing `Blue native polyacrylamide gelelectrophoresis (BN-PAGE)'(Schägger et al., 1991). In this first dimension, protein complexes are separated on the basis of their size. To exclude co-migration of several complexes, a second native dimension (ionexchange 'FPLC) will be incorporated. Samples are subsequently subjected to a denaturing second dimension, SDS-PAGE, in which the complexes will break up into their constituents. With this strategy, the dynamics of the complexes can by followed accurately during their progression through the cell cycle. Together with the TAP-technology group of dr. Geert De Jaeger, the cell cycle interactome will be studied and this can reveal new players during the cell cycle. Post-translational modifications like phosphorylation and glycosylation are important for the activity, stability and formation of protein complexes and will be studied.Identification of protein complexes with changes in abundancy or/and modifications is done by mass spectromectric analysis.

Researcher(s)

• Promoter: Prinsen Els
• Promoter: Van Onckelen Harry
• Co-promoter: Witters Erwin
• Fellow: Remmerie Noor

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Prinsen Els
• Promoter: Van Onckelen Harry
• Fellow: Swiatek Agnieszka

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Since the use of the chemical growth regulator CCC has been omitted for pear, the optimal balance between vegetative and generative growth of pear trees is impaired. Fruitsetting is the best controller of vegetative growth. Therefore, there is a trend to control fruitsetting via Gibberellin treatment. A new growth retardant, Prohexadione-Calcium, a blocker of the GA biosynthesis, has been developed. Systematic treatment by this GA blocker of exogenous GA's blindly interferes with the natural hormone homeostasis of the trees. This might induce severe risks in the predictability of flower bud induction. This project aims the analysis of (1) fruitsetting, (2) the molecular-physiological background and (3) the phytohormone balance after treatment with GA3, GA4/7 and Prohexadione Calcium on 4-year old Conference pear trees.

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Each plant starts from a minimal embryo. Plant growth is the result of a defined process where each tissue generates new cells, which on their turn expand and differentiate. This research community will focus on the role of phytohormones on cell division, cell expansion, root development, flower induction, apical dominance, dormancy, UV tolerance and photosynthesis. The research community groups 14 research units from 12 different universities/research institutes.

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Bacterial leaf nodulation is a model of exceptional collaboration of bacteria and higher plants. The presence of the endosymbiont is absolutely required to ascertain survival of the host. Several possible factors might be involved in leaf nodulation, including nitrogen fixation and production of plant growth promoting substances by the bacteria. By looking for the presence of bacterial genes encoding nitrogen fixation and/or hormone synthesis, we will provide this research with a genetic basis to evaluate the extend to which these two organisms mutually interact.

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Prinsen Els
• Promoter: Van Onckelen Harry

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Abscisic acid is a phytohormone that, besides ethylene and jasmonate, plays an important role in the interaction between plants and pathogenic micro-organisms. Research at the RUG has shown that ABA mutants of tomato are much more resistant to Botridis cinerea and Sclerotinia sclerotiorum than WT plants, but they do not show a changed susceptibility to the biotrophic pathogen Oidium lycopersici. The hypothesis that we want to test in this project is that certain broad spectrum pathogens interfere with a decrease in ABA after infection by producing ABA or stimulating ABA production by the host (or suppress ABA breakdown by the host). Because of this, defence reactions of the plant are suppressed. This could explain why interactions with these pathogens are generally compatible. We want also to study whether broad spectrum AM use similar mechanisms to suppress plant defense.

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Auxins, specifically indole-3-acetic Acid (IAA), are synthesized by plants, fungi and bacteria. The physiological role as well as the signal transduction cascade in plants has been studies intensively yet. However, auxin biosynthesis is poorly understood. This project aims to understand the IAA biosynthesis by Azospirillum brasilense. The experimental plan has 3 levels: (1) Regulation of ipdC expression, (2) biochemical analsis of purified IPyA-decarboxylase and (3) Quantitative analysis of IAA- metabolites and mRNA's, corresponding with IPyP-decarboxylase and regulatory proteins involved in ipdC gene expression, of cells grown under strictly controlled conditions.

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

The objective of the IUAP proposal "Growth and development of higher plants" is to understand how plant roots develop and interact with the environment. To this end 14 research groups from 6 universities and 1 research institute will join forces and integrate their respective expertises in genomics, proteomics, map-based cloning of mutants, morphology, hormone analysis, physiology and bio-informatics.

Researcher(s)

• Promoter: Van Onckelen Harry
• Co-promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Broomrapes (Orobanche spp.) are obligate root parasites of many crops. Parasitism by the root parasites often results in severe yield losses. The seeds of those parasites germinate only in response to specific chemical signal(s) released from the host plant roots. Orobanche ramosa and O. cumana seeds germinate in the presence of their respective host tobacco and sunflower. A determination of the germination stimulants released from sunflower and tobacco roots is of great importance from a theoretical and practical point of view. The aim of this study is to clarify the correlation between the dynamic in quantity of plant hormones during the infection process and their role for triggering the defense reaction of the host plant. Determination of the nature of the plant host specific substances responsible for provoking the parasite seed germination will be our main goal. These experiments will give an opportunity to study the interactions between hosts and parasites and to go in more details by biochemical investigations of the chemical signals between tobacco and sunflower from one side and the Orobanche spp. from the other side.

Researcher(s)

• Promoter: Prinsen Els
• Fellow: Slavov Slavtcho Bonev

Research team(s)

Project type(s)

• Research Project

Abstract

The production of trangenic plants involves two critical steps: (1) the introduction and stable integration of foreign DNA in somatic cells and, (2) the formation of shoots or embryos from these cells i.e. in vitro regeneration This study should lead to the isolation of a gene that is involved in conferring in vitro regeneration capacity. In addition, the use of NlLs allows for an unbiased examination of the regeneration competent genotype. At the UIA, we will focuss on the hormonal involvement in this regeneration competence. Introduction of the L. peruvianum Rg-1 allel in recalcitrant genotypes of different species through transgenesis may release regeneration capacity in these genotypes, with obvious benefits for transgenic plant production and micropropagation.

Researcher(s)

• Promoter: Prinsen Els
• Co-promoter: Van Onckelen Harry

Research team(s)

Project type(s)

• Research Project

Abstract

About the role of plant hormones in nodulation no direct data are available but it seems plausible that auxins and especially cytokinins are involved in the nodulation proces. It is not known whether this occurs via altered hormone balances or via altered hormone susceptibilities. Moreover, it can not be excluded that bacterial production of plant hormones could contribute to certain aspects of nodule development. The aim of the present project on the Azorhizobium caulinodans-Sesbania rostrata symbiosis is to answer the following questions : (i) Nod-factor producing bacteria do they induce a local redistribution in the endogenous auxin-cytokinin balance and (ii) how does bacterial phytohormone synthesis contributes in nodule development?

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Clubroot is a gal!-forming pathogen of brassicas which can have devastating effects on crop yield. The aim of this project is to measure the changes in the amounts and ratios of the diffe.rent forms of plant hormones during clubroot infection and subsequent gal! formation. This information is critica' to an understanding of (a) how alterations in plant hormones lead to gal! formation in the susceptible cultivar and (b) to the basis of tolerance to clubroot.

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

The symbiotic relationship between bacteria and tropical Rubiaceae belonging to the genera Sericanthe, Pavetta, Psychotria, Pachystigma and Fadogia is obligate in the development of the host. The symbiosis is visible through small leaf galls which are colonised by bacteria. This research project will focus on the role of bacterial hormone metabolism in Psychotria kirkii and P. Calvia in relation to development of the host plant, flower induction and bacterial colonisation.

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

Project type(s)

• Research Project

Abstract

About the role of plant hormones in nodulation no direct data are available but it seems plausible that auxins and especially cytokinins are involved in the nodulation proces. It is not known whether this occurs via altered hormone balances or via altered hormone susceptibilities. Moreover, it can not be excluded that bacterial production of plant hormones could contribute to certain aspects of nodule development. The aim of the present project on the Azorhizobium caulinodans-Sesbania rostrata symbiosis is to answer the following questions : (i) Nod-factor producing bacteria do they induce a local redistribution in the endogenous auxin-cytokinin balance (ii) what is the role of the endogenous gibberellin metabolism during nodulation and (iii) how does bacterial phytohormone synthesis contributes in nodule development?

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

Project type(s)

• Research Project

Abstract

Bacteria of the nitrogen-fixing genus Azospirillum produce phytohormones. This excretion of phytohormones by plant associated bacterie may promote plant growth and improve crop yield. This project has four main objectives:(l) characterization of pathways involved in auxin metabolism in Azospirillum brasilense; (2) characterization of precursors of the tryptophan--independent pathway; (3) interregulation and interaction between different auxin metabolic pathways; (4) analysis of the functional relevance of microbial phytohormone synthesis upon the interaction with the hostplant.

Researcher(s)

• Promoter: Prinsen Els
• Fellow: Van Laer Stijn

Research team(s)

Project type(s)

• Research Project

Abstract

The research topics on plant developmental physiology can be summarised as followed (i) the role of phytohormones in the signal transduction cascade in plant-bacterium interactions, (ii) the role of phytohormones during biotic stress and (iii) the signal transduction cascade and mode of action of auxins and cytokinins.

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

Project type(s)

• Research Project

Abstract

A panoplia of microorganisms are associated with higher plants. The interactions can be very diverse going from associated to intimate and from benificial to pathogenic. In this Research Community, Plant-microbe interactions are studied multidisciplinary : (i) ecological aspects, (ii) molecular mechanisms of the mode of recognition, (iii) changes in behaviour en/or gene expression of both partners. This research community is the follow up of a research community called 'Molecular aspects of Plant-Microbe Interactions' directed by prof. Dr. J. Vanderleyden (KUL).

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

• Integrated Molecular Plant Physiology Research (IMPRES)

Project type(s)

• Research Project

Abstract

Bacteria of the nitrogen-fixing genus Azospirillum produce phytohormones. This excretion of phytohormones by plant associated bacterie may promote plant growth and improve crop yield. This project has four main objectives:(l) characterization of pathways involved in auxin metabolism in Azospirillum brasilense; (2) characterization of precursors of the tryptophan--independent pathway; (3) interregulation and interaction between different auxin metabolic pathways; (4) analysis of the functional relevance of microbial phytohormone synthesis upon the interaction with the hostplant.

Researcher(s)

• Promoter: Prinsen Els
• Fellow: Van Laer Stijn

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

Project type(s)

• Research Project

Abstract

Although auxins and cytokinins control nearly all aspect of plant growth and development, little is know about the underlying mechanisms of signal transduction and mode of action. This research project aims to elucidate the phytohormone signal transduction cascade of auxines and cytokinins addressing the following questions:(1 )What is the auxin cofactor ? (2) Do IAA metabolites IAN, IEt, and IAA-conjugates work as auxins and what is their function in the IAA signal transduction cascade ? (3) Are the rolA and rolB gene products functionally related with the auxin and/or cytokinin signal transduction cascade? (4) Have coniferylalcohol, dihydroconiferylalcohol, their dimers or glucosides a key function in auxin or cytokinin action? (5) Have the auxin and cytokinin signal transduction pathway a common foundation ? (6) Is there an interrelation between the ENOD40 peptide and auxins and/or cytokinins ? (7) Where in the auxin and cytokinin signal transduction pathway can we locate axi and cyi ? (8) Where in the auxin and cytokinin signal transduction pathway can we locate lipochitooligosaccharides ?

Researcher(s)

• Promoter: Van Onckelen Harry
• Fellow: Prinsen Els

Research team(s)

Project type(s)

• Research Project

Abstract

Bacteria of the nitrogen-fixing genera Azospirillum and Rhizobium live in association and symbiosis respectively with roots of many plants. Like most rhizosphere bacteria, members of these bacterial genera produce phytohormones. This excretion of phytohormones by associated bacteria may promote plant growth and improve crop yield. Azospirillum and Rhizobium are chosen as case models due to their different ecological niche (root surface rep. intracellular) which possibly iffluences the regulation of auxin biosynthesis. The research project presented here has three rnain objectives:(i) characterisation of pathways involved in auxin metabolism; (ii) inter-regulation and interaction between different auxin metabolic pathways; (iii) analysis of the functional relevance of microbial (iii) phytohormone synthesis upon the interactions with the host.

Researcher(s)

• Promoter: Prinsen Els

Research team(s)

Project type(s)

• Research Project

Abstract

The excretion of phytohormones by associated bacteria may promote plant growth and improve crop yield. This project has hree objectives : (1) characterization of pathways involved in auxin metabolism (2) inter-regulation and interaction between different auxin metabolic pathways (3) analysis of the functional relevance of microbial phytohormone synthesis upon the interactions with the host.

Researcher(s)

• Promoter: Van Onckelen Harry
• Fellow: Prinsen Els

Research team(s)

Project type(s)

• Research Project