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Introduction
My research was focused on investigating the physiological processes underlying the mechanism of adaptation of plants to the environment. The regulatory aspects of the sulfur uptake and assimilation in plants in relation to the metabolic requirement for growth and the signals therein involved were investigated at various physiological conditions.
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Publications
Publications (243)
In crops such as maize (Zea mays) sulfur is essential for physiological functioning and cell signaling. We assume that GSH precursors cysteine and γ-glutamylcysteine (γ-EC) are directly involved in the regulation of plant sulfur metabolism. Chloroplasts (chl) and the cytosol (cy) are key locations of sulfur metabolism and GSH synthesis in maize cel...
Brassica species contains sulfur-containing secondary compounds including glucosinolates which might protect plants from pathogens. In the present investigation, the first leaves of Brassica rapa were grown in different situations such as sulfate-sufficient and deprived conditions, and infected with two types of fungi namely, Alternaria brassicicol...
Chapter 6 of Marschner's Mineral Nutrition of Plants, Fourth Edition. This book presents sections on the uptake and transport of nutrients in plants, root-shoot interactions, the role of mineral nutrition in yield formation, stress physiology, water relations, functions of mineral nutrients and contribution of plant nutrition to nutritional quality...
Nutrient deficiency is known to constrain plant growth in numerous ways, but how it impacts floral displays and pollination success remains unclear. Here we investigate how insufficient availability of sulphur-a vital plant nutrient that is a limiting factor in natural and agricultural regions throughout the world-influences the production of flora...
To study the regulation of sulfate metabolism in barley (Hordeum vulgare), seedlings were exposed to atmospheric hydrogen sulfide (H 2 S) in the presence and absence of a sulfate supply. Sulfate deprivation reduced shoot and root biomass production by 60% and 70%, respectively, and it affected the plant's mineral nutrient composition. It resulted i...
Main conclusion:
Stomatal aperture in maize is not affected by exposure to a subtoxic concentration of atmospheric H2S. At least in maize, H2S, thus, is not a gaseous signal molecule that controls stomatal aperture. Sulfur is an indispensable element for the physiological functioning of plants with hydrogen sulfide (H2S) potentially acting as gaso...
Throughout the world anthropogenic activity has resulted in enhanced soil nickel (Ni2+) levels, which may negatively affect plant productivity. The physiological background of Ni2+ phytotoxicity is still largely unclear. Ten-day exposures of Brassica rapa seedlings to 1, 2 and 5 μM NiCl2 resulted in strongly enhanced tissue Ni levels, a decreased b...
In polluted areas, plants may be exposed to supra‐optimal levels of the micronutrient molybdenum. The physiological basis of molybdenum phytotoxicity is poorly understood. Plants take up molybdenum as molybdate, which is a structural analogue of sulphate. Therefore, it is presumed that elevated molybdate concentrations may hamper the uptake and sub...
Hydrogen sulfide (H2S) is an air pollutant present at high levels in various regions. Plants actively take up H2S via the foliage, though the impact of the gas on the physiological functioning of plants is paradoxical. Whereas elevated H2S levels may be phytotoxic, H2S levels realistic for polluted areas can also significantly contribute to the sul...
Salinity stress in Brassica, often only associated with osmotic effects and the toxicity of Na+, was more severe when applied as Na2SO4 than as NaCl, indicating that SO42- ions had toxic effects as well. Application of 10 mM calcium in the form of CaCl2 in the growth medium of plants only slightly ameliorated growth impairment by NaCl and KCl, but...
Seedlings of Brassica rapa were exposed to increasing concentrations of NaCl,
Na2SO4, KCl and K2SO4 to study the effect on glucosinolate content, composition
and expression of genes of the glucosinolate biosynthetic pathway and associated
transcription factors. Growth was inhibited stronger by sulphate salts and strongest
by Na2SO4. Aliphatic, indo...
Seedlings of Brassica rapa were exposed to increasing concentrations of NaCl, Na2SO4, KCl and K2SO4 to study the effect on glucosinolate content, composition and expression of genes of the glucosinolate biosynthetic pathway and associated transcription factors. Growth was inhibited stronger by sulphate salts and strongest by Na2SO4. Aliphatic, indo...
This proceedings volume contains a selection of invited and contributed papers of the 10th International Workshop on Sulfur Metabolism in Plants, which was held in Goslar, Germany September 1-4, 2015. The focus of this workshop was on the fundamental, environmental and agricultural aspects of sulfur in plants, and presents an overview of the progre...
Dimethylsulfoniopropionate (DMSP) is a secondary sulfur compound that is present in high levels in several marine algal species and some higher plant species. DMSP has also been detected in low levels in some other plant species, though its overall occurrence within the plant kingdom remains unclear. The physiological function of DMSP in saline alg...
Plants in coastal salt marshes have to deal with salinity, anoxia and excessive reduced sulfur at the same time. Sulfur metabolism is presumed to have significance in plant stress-tolerance. In order to obtain more insight into the physiological significance of sulfur metabolism in plant responses to multiple abiotic stress factors, the glycophyte...
The activated methyl cycle is a central metabolic pathway used to generate (and recycle) several important sulfur-containing metabolites including methionine, S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) and enable methylation. We have developed a precise and sensitive method for the simultaneous measurement of several sulfur metabol...
Proton-selective microelectrodes were used to determine sulfate uptake by roots of intact plant seedlings. The response of H+ fluxes to sulfate addition showed to be a good proxy for sulfate uptake by the sulfate/H+ co-transport system. H+ influx and increase in root surface pH was much higher in sulfate-deprived seedlings than in seedlings grown w...
Manganese (Mn) is an essential plant nutrient, though at elevated levels in plant tissues it may become toxic. The physiological basis for phytotoxicity is largely unclear. Exposure of Brassica rapa to elevated levels of Mn2+ in the nutrient solution resulted in decreased biomass production at ≥ 20 µM and chlorosis. The Mn content in the shoot incr...
The atmospheric CO2 concentration ([CO2]) is increasing and predicted to reach ∼550 ppm by 2050. Increasing [CO2] typically stimulates crop growth and yield, but decreases concentrations of nutrients, such as nitrogen ([N]), and therefore protein, in plant tissues and grains. Such changes in grain composition are expected to have negative implicati...
Background and aimsIt remains uncertain whether a higher toxicity of either NaCl or Na2SO4 in plants is due to an altered toxicity of sodium or a different toxicity of the anions. The aim of this study was to determine the contributions of sodium and the two anions to the different toxicities of chloride and sulfate salinity. The effects of the dif...
In different ecosystems herbivores highly prefer particular plant species. This is often explained in a stoichiometric framework of nutrient-based plant adaptations to herbivory. We hypothesize that such super-palatability can also arise as an evolutionary by-product of osmoregulatory adaptations of plants to stressful environmental conditions, as...
The title ‘Phosphorus in Agriculture: 100 % Zero’ is synonymous for make-or-break. And it stands up to the promise. This book sends an important message as it delivers background information, intrinsic hypotheses, validation approaches and legal frameworks, all for balanced phosphorus fertilization in agriculture. This implies firstly that the phos...
Sulfur deficiency in plants has severe impacts on both growth and nutrient composition. Fumigation with sub-lethal concentrations of H2S facilitates the supply of reduced sulfur via the leaves while sulfate is depleted from the roots. This restores growth while sulfate levels in the plant tissue remain low. In the present study this system was used...
Exposure of plants to elevated CO2 (eCO2) has a number of physiological effects, including increased photosynthetic carbon fixation and decreased stomatal conductance, resulting in greater growth and yield and also improved water use efficiency. Therefore, eCO2 is considered to ameliorate the adverse effects of drought. To test this assumption in e...
Rising atmospheric CO2 concentrations (e[CO2 ]) are presumed to have a significant impact on plant growth and yield and also on mineral nutrient composition, and therefore on nutritional quality of crops and vegetables. To assess the relevance of these effects in future agroecosystems it is important to understand how e[CO2 ] interacts with other e...
Increasing soil salinity is a major threat to crop production in many agricultural areas throughout the world. Although sodium chloride (NaCl) is one of the most abundant salts in soils, others viz. sulfate salts may also be present in high concentrations in some soil types. Sulfate salts, e.g. Na2SO4, are still widely under-represented amongst sal...
This proceedings volume contains a selection of invited and contributed papers of the 9th International Workshop on Sulfur Metabolism in Plants, which was hosted by the Albert-Ludwigs-University Freiburg and held at Schloss Reinach, Freiburg-Munzigen, Germany from April 14-17, 2014.
The focus of this workshop was on molecular physiology and ecophys...
The impact of sulfate deprivation and atmospheric H2S and SO2 nutrition on the content and composition of glucosinolates was studied in Brassica juncea and B. rapa. Both species contained a number of aliphatic, aromatic and indolic glucosinolates. The total glucosinolate content was more than 5.5-fold higher in B. juncea than in B. rapa, which coul...
Sulfide is the endproduct of assimilatory sulfate reduction in chloroplasts. It is then used by O-acetylserine(thiol)lyase (OAS-TL) to produce cysteine, the source of reduced sulfur in plants. While its formation in chloroplasts is essential for plant metabolism, sulfide is also a potent toxin mainly targeting respiration in mitochondria. Here, the...
Brassica juncea seedlings contained a twofold higher glucosinolate content than B. rapa and these secondary sulfur compounds accounted for up to 30% of the organic sulfur fraction. The glucosinolate content was not affected by H2S and SO2 exposure, demonstrating that these sulfur compounds did not form a sink for excessive atmospheric supplied sulf...
Knowledge on the underlying physiological processes and variables which bias their contribution to nutrient use efficiency (NUE) is crucial to develop strategies for improvement in agroecosystems. This chapter aims to contribute to the understanding of the physiological basis of NUE to develop strategies for improvement by modern breeding, but also...
Nutrient Use Efficiency in Plants: Concepts and Approaches is the ninth volume in the Plant Ecophysiology series. It presents a broad overview of topics related to improvement of nutrient use efficiency of crops.
Nutrient use efficiency (NUE) is a measure of how well plants use the available mineral nutrients. It can be defined as yield (biomass) p...
Zinc (Zn) is a plant nutrient; however, at elevated levels it rapidly becomes phytotoxic. In order to obtain insight into the physiological background of its toxicity, the impact of elevated Zn2+ concentrations (1 to 10 μM) in the root environment on physiological functioning of Chinese cabbage was studied. Exposure of Chinese cabbage (Brassica pek...
Glucosinolates are secondary sulfur compounds, especially found in Brassicaceae, which may function in plant defense against insects, herbivory and pathogens and have anti-carcinogenic properties. The content of the glucosinolates varies strongly between species, cultivars, developmental stage and may be
affected by the plant sulfur supply/status....
Copper and zinc are essential nutrients for the plants; however, they become rapidly phytotoxic at elevated concentrations in the root environment. Exposure of Chinese cabbage to elevated Cu2+ (≥ 2 μM) or Zn2 + concentrations (≥ 5 μM) resulted in leaf chlorosis and subsequently in a loss of photosynthetic activity and a strongly reduced biomass pro...
The knowledge about the response of the sulfate uptake system of plants to sulfate deficiency on the level of gene expression has increased a lot during the last decades. However, there is still a need for a deeper understanding of the bio- and electro- chemical processes involved in plant adaptation to sulfate deficiency. Ion-selective microelectr...
The toxicity of high copper (Cu) concentrations in the root environment of Chinese cabbage (Brassica pekinensis) was little influenced by the sulphur nutritional status of the plant. However, Cu toxicity removed the correlation between sulphur metabolism-related gene expression and the suggested regulatory metabolites. At high tissue Cu levels, the...
Biomass production, dry matter content, specific leaf area and pigment content of Chinese cabbage were all quite similar, when plants were grown in the absence or presence of UV-A + B (2.2 mW cm−2). Elevated Cu2+ concentrations (2–10 μM) in the root environment and UV radiation had negative synergistic effects for Chinese cabbage and resulted in a...
http://www.sciencedirect.com/science/journal/00988472/88
Sulphur-containing metabolites play an important role in metabolism and homeostasis. Determination of these metabolites is challenging owing to their low concentrations and the interference in mass spectrometry analysis.
To develop a sensitive and accurate method based on liquid chromatography, electrospray ionisation, tandem mass spectrometry (LC-...
Nitrogen and sulfur are essential for crop growth and quality, because both are needed for amino acid and protein synthesis. The organic N/S ratio on a molar basis is usually about 20. Plants, therefore, must have mechanisms to coordinate sulfur and nitrogen uptake and assimilation so that appropriate proportions of sulfur containing and other amin...
Leaf discs from sulfur-sufficient and sulfur-deprived Chinese cabbage plants
were incubated at various levels of sulfate (ranging from 0 - 40 mM) for 24 h in the
light. Sultr4;1 was the sole constitutively expressed sulfate transporter present in sulfatesufficient
leaf discs and its expression was enhanced upon incubation at ≤ 8 mM and
decreased at...
If Chinese cabbage was grown hydroponically at various sulfate concentrations
ranging from 5 to 100 μM in the root environment, it was able to maintain its growth even at 5
and 10 μM, concentrations close to the Km of the Group 1 high affinity sulfate transporters. The
sulfate uptake capacity of the roots was up-regulated at ≤ 25 μM sulfate, howeve...
Plants are able to use gaseous sulfurous air pollutants as a sulfur source for growth, especially under circumstances where the sulfur supply to the roots is limited. In Eucalyptus camaldulensis seedlings there was a direct interaction between atmospheric H2S exposure and the uptake of sulfate by the root. At an ample sulfate supply, exposure of E....
Exposure of Chinese cabbage (Brassica pekinensis) to enhanced Cu2+ level (4 μM) resulted in a reduced plant biomass production and an increased shoot to root ratio at both sulfate-sufficient and sulfate-deprived conditions. However, sulfate deprivation had a more rapid negative affect on plant biomass production than an enhanced Cu2+ level, The exp...
Reduced sulfur is necessary for synthesis of various essential compounds in the plant cell including cysteine and glutathione. For this reason sulfide is continuously produced in plastids as intermediate of the assimilatory sulfate reduction pathway. Varying demand for sulfide during development and in response to external stress challenges a plant...
An analytical method was developed for the accurate quantification of the contents of sulfur metabolites of plant tissues based on liquid chromatography – electrospray ionization – tandem mass spectrometry (LC-ESI-MS/MS). 34S-Labeled sulfur metabolites were biosynthesized in Arabidopsis thaliana from 34S-SO
42− and used as internal standards for th...
In higher plants, biosynthesis of cysteine is catalysed by OAS-TL [O-acetylserine(thiol)lyase], which replaces the activated acetyl group of O-acetylserine with sulfide. The enzyme is present in cytosol, plastids and mitochondria of plant cells. The sole knockout of mitochondrial OAS-TL activity (oastlC) leads to significant reduction of growth in...
Exposure of Chinese cabbage (Brassica pekinensis) to enhanced Cu(2+) concentrations (1-10 mu M) resulted in leaf chlorosis, a loss of photosynthetic capacity and lower biomass production at >= 5 mu M. The decrease in pigment content was likely not the consequence of degradation, but due to hindered chloroplast development upon Cu exposure. The Cu c...
http://onlinelibrary.wiley.com/doi/10.1111/plb.2009.11.issue-s1/issuetoc
Throughout the world, natural and agro-ecosystems are at risk from sulfurous air pollutants. However, establishing cause–effect relationships for these air pollutants, and determining acceptable atmospheric concentrations of them, are complicated by their paradoxical effects on plant functioning. Sulfurous air pollutants can act as both toxin and n...
Both activity and expression of sulfate transporters and APS reductase in plants are modulated by the sulfur status of the plant. To examine the regulatory mechanisms in curly kale (Brassica oleracea L.), the sulfate supply was manipulated by the transfer of seedlings to sulfate-deprived conditions, which resulted in an up to 3-fold increase in the...
Nutrient-sufficient and nitrate- or sulfate-deprived plants of Brassica oleracea L. were exposed to 4 microl l(-1) NH3 (2.8 mg m(-3)), and effects on biomass production and allocation, N-compounds and root morphology investigated. Nitrate-deprived plants were able to transfer to atmospheric NH3 as nitrogen source, but biomass allocation in favor of...
Sustainable development is development that meets the needs of the present withoutcompromising the ability of future generations to meet their own needs”. One importantaspect of sustainable development in agriculture is the responsible management ofnatural resources of which soils and water bodies are the most endangered ones. Amajor threat for soi...
The activity and expression of sulfate transporters and adenosine 5′-phosphosulfate (APS) reductase (APR) in plants are modulated by the plant sulfur status and the demand for growth. To elucidate regulatory mechanisms in Chinese cabbage [Brassica pekinensis (Lour.) Rupr.], the interactions between atmospheric H2S and sulfate nutrition and the impa...
Sulfur is essential for plant growth and functioning. Sulfate taken up by the roots is the primary sulfur source for growth,
but additionally plants are able to utilize absorbed sulfur gases by the shoot. Prior to its assimilation sulfur needs to
be reduced and cysteine is the primary precursor or sulfur donor for other plant sulfur metabolites. Su...
The uptake and distribution of sulfate in BRASSICA OLERACEA, a species characterised by its high sulfate content in root and shoot, are coordinated and adjusted to the sulfur requirement for growth, even at external sulfate concentrations close to the K (m) value of the high-affinity sulfate transporters. Plants were able to grow normally and maint...
Combining an ecosystems approach with new insights at the molecular and biochemical level, this book presents the latest findings on how plants respond, physiologically, to sulphur in their environment. It explores key areas – such as biotic and abiotic interactions, adaptations to fluctuating supply, and sulphur’s role in plant metabolic networks...
Presentation at 12th Int. Rapeseed Congress, Wuhan, P.R. China, 26 – 30. March 2007
Silvia Haneklaus 1, Elke Bloem 1, Luit J. De Kok 2, Zhihui Yang 3, Shiping Wang 4, Ewald Schnug 1
1 Institute of Plant Nutrition and Soil Science, Federal Agricultural Research Centre (FAL), Bundesallee 50, D-38116 Braunschweig, Germany
2 Laboratory of Plant Phy...
The reduction of adenosine 5′-phosphosulphate (APS) by APS reductase (APR) is considered to be one of the rate-limiting steps
in the assimilation of sulphur in plants. In order to identify the mechanisms of regulation of this enzyme, the impact of
atmospheric H2S exposure on mRNA expression, protein level, and activity of APR was studied in two spe...