Burkhard Sattelmacher

Significance of nickel for plant growth and metabolism

Ni is the most recent candidate to be added to the list of 13 essential mineral elements for higher plants although failure to complete the life cycle in the absence of Ni has only been demonstrated in a few plant species. Ni is considered an essential element primarily because of its function as an irreplaceable component of urease which is responsible for the hydrolysis of urea N, and which seems to be the only proven nutritional function of Ni in higher plants. For production of full urease activity and growth on urea N a critical deficiency level of around 100 μg kg—1 DW seems appropriate, while plants depending on mineral N may have a lower Ni requirement. Ni has also other effects on plant growth, of which the phytosanitary action is possibly most significant in the field. The incorporation of Ni into urease apoprotein requires the active participation of several accessory proteins, and mutations in genes coding the accessory proteins as well as the urease apoprotein have been exploited to characterise aspects of urease activation. The mobility of Ni within the plant, as compared to other heavy metals, is usually high, although little is known of the uptake mechanisms and the form of transported Ni under Ni-deprived conditions. This as well as other effects of Ni that cannot be related to its structural component of urease, remain to be elucidated. Die Bedeutung von Nickel fur das Wachstum und den Stoffwechsel von Pflanzen Ni ist der jungste Kandidat fur die Liste der bisher 13 essentiellen mineralischen Nahrelemente hoherer Pflanzen, obwohl der Beweis fur seine Notwendigkeit zur Vollendung des Lebenszyklus einer Pflanze erst bei wenigen Arten gelang. Die Essentialitat von Ni begrundet sich insbesondere auf dessen Funktion als unersetzlicher Bestandteil des Enzyms Urease, welches die Hydrolyse von Harnstoff katalysiert. Dies ist die bislang einzige nachgewiesene Funktion von Ni in der hoheren Pflanze. Hinsichtlich des Wachstums harnstoffernahrter Pflanzen und der Ureaseaktivitat konnte ein kritischer Gehalt von etwa 100 μg kg—1 TM abgeleitet werden, wahrend Pflanzen, die mineralischen N erhalten, einen wesentlich geringeren Ni-Bedarf haben. Ni hat noch weitere Effekte auf das Pflanzenwachstum, von denen die phytosanitaren Wirkungen unter Feldbedingungen sicherlich die wichtigsten sind. Der Einbau von Ni in die Ureaseapoproteine erfordert die aktive Beteiligung mehrerer akzessorischer Proteine und Mutationen der Gene, die diese akzessorischen Proteine und die Ureasestrukturgene kodieren, wurden erfolgreich zur Aufklarung zahlreicher Aspekte der Ureaseaktivierung eingesetzt. Die innerpflanzliche Mobilitat von Ni ist, verglichen mit anderen Schwermetallen, normalerweise relativ hoch, doch liegen nur wenige Informationen uber die Ni-Aufnahme und transportierten Ni-Spezies bei niedrigem Ni-Angebot vor. Diese und andere Aspekte der Ni-Ernahrung, die nicht auf dessen strukturelle Bedeutung in der Urease zuruckgefuhrt werden konnen, harren ihrer Untersuchung.

Interaction between root growth and mineral nutrition

Abstract The close interrelationships between root growth and mineral nutrient supply on the one hand, and root parameters and genotypic differences in mineral nutrient efficiency on the other, are demonstrated using three examples from maize.

Apoplastic Ion Concentration of Intact Leaves of Field Bean (Vicia faba) as Influenced by Ammonium and Nitrate Nutrition

Summary In order to differentiate between free and exchangeable apoplastic cations, intact leaves of Vicia faba were vacuum infiltrated with solutions differing in cation exchange strength (water and 50 mol · m -3 BaCl 2 ). Apoplastic washing fluids were subsequently obtained by careful centrifugation. While for the bivalent cations Ca 2+ and Mg 2+ it was possible to differentiate between a free and bound fraction this was not the case with K + . Concentration of free apoplastic Ca 2+ and K + varied between 0.3–0.8 mol· m -3 and 1.3–4.5 mol · m -3 , respectively. Total apoplastic Ca 2+ accounted for up to 40 % of total leaf Ca 2+ content while just 1–8 % of total leaf Mg 2+ and K + content were found in this compartment. Surprisingly, the N-form revealed little influence on apoplastic ion concentration. Independently from the form of N-nutrition, NH 4 + was not found in the leaf apoplast while NO 3 - concentration was rather low (0.01–0.03 mol · m -3 ). The pH of the intercellular washing fluid (PH 6.1) remained unaffected by the N-form.

Cytoplasmic Ca2+-H+-exchange buffers in green algae

SummaryFluorescence ratio imaging was used for simultaneous measurement of cytosolic pHc and pCac inChara corallina, Nitella flexilis, andEremosphaera viridis. In some experiments the electrical membrane potential was also recorded. The first hint of coupling between changes in pHc and pCac was found in characean cells when the influence of butyrate on cytosolic streaming was studied by laser-Doppler-anemometry (LDA). The observed butyrate-induced cessation of cytosolic streaming supports the assumption that changes in pHc cause changes in pCac. This hypothesis was tested by simultaneously loading cells with Fura-2-dextran and BCECF-dextran. The addition of butyrate revealed strong coupling between pCac and pHc although this only occurred when the difference between pHc and pCac was less than 0.4 units (± 0.24, n=7). The measured relationship between the changes in pCac and pHc could be fitted by a cytoplasmic buffer exchange process. Protons imported by butyrate into the cytoplasm are able to displace Ca++ ions from cytoplasmic buffer sites. Three dissociation constants of the cytoplasmic buffer were pK1=6.2, pK2=7.1 for proton buffering, and pKca=6.7 for Ca++ ion buffering. Other possible mechanisms, such as butyrate-induced Ca++ influx through the plasmalemma and Ca++ release from internal stores are discussed. They are not necessary to explain the observed coupling but cannot be excluded from the process. Using the butyrate technique, the cytosolic in vivo proton buffer capacities ofN. flexilis, C. corallina, andE. viridis were determined as βi=30 mM · H+/pH-unit, βi=46 mM · H+/pH-unit, and βi=90 mM · H+/pH-unit, respectively. The values obtained in vivo are greater than those found previously using extraction methods. This can be explained in terms of pump activity and exchange with cell organelles, i.e., the vacuole. The high value of βi found inEremosphaera reflects adaptation to its habitat.

31P nuclear magnetic resonance evidence for differences in intracellular pH in the roots of maize seedlings grown with nitrate or ammonium

Summary 31 P nuclear magnetic resonance (NMR) spectroscopy was used to measure the cytoplasmic and vacuolar pH values in maize ( Zea mays ) root tissues from seedlings grown in nutrient solutions at different pH values with either nitrate or ammonium as the source of nitrogen. The nitrogen form had little effect on intracellular pH at pH 6, but differences were found at pHs 4 and 8 with the largest effects occurring in root tips with ammonium supply. Intracellular pH in roots was regulated more tightly in the nitrate grown plants than in the ammonium grown plants and it was concluded that the influx of free ammonia at pH 8 and the unfavourable energetics of H + excretion at low external pH were responsible for this difference.

The Apoplast of Higher Plants: Compartment of Storage, Transport and Reactions

DEDICATION IN MEMORY OF BURKHARD SATTELMACHER: Walter Horst Preface: Burkhard Sattelmacher and Walter Horst FOREWORD:THE PLANT-LEAF APOPLAST: D.T. Clarkson Section 1: CELL WALL - ION INTERACTIONS - SIGNIFICANCE FOR NUTRITION OF PLANTS AND THEIR STRESS TOLERANCE CELL WALL - ION INTERACTIONS: N. Carpita BORON IN THE APOPLAST OF HIGHER PLANTS: M.A. Wimmer and H.E. Goldbach SILICON IN PLANT NUTRITION: H. Wiese, M. Nikolic and V. Romheld SIGNIFICANCE OF THE ROOT APOPLAST FOR ALUMINIUM TOXICITY AND RESISTANCE OF MAIZE: W.J. Horst, M. Kollmeier, N. Schmohl, M. Sivaguru, Y. Wang, H.H. Felle, R. Hedrich, W. Schroder and A. Stass SIGNIFICANCE OF POLYAMINES FOR PECTIN-METHYLESTERASE ACTIVITY AND THE ION DYNAMICS IN THE APOPLAST: J. Gerendas Section 2: THE ROOT APOPLAST - IMPLICATION FOR ION ACQUISITION AND SHORT-DISTANCE TRANSPORT THE APOPLAST: A KINETIC PERSPECTIVE: A. Glass, THE APOPLAST OF ECTOMYCORRHIZAL ROOTS - SITE OF NUTRIENT UPTAKE AND NUTRIENT EXCHANGE BETWEEN THE SYMBIOTIC PARTNERS: H. Bucking, R. Hans and W. Heyser CHEMICAL COMPOSITON OF APOPLASTIC TRANSPORT BARRIERS IN ROOTS:L. Schreiber, R. Franke and K. Hartmann APOPLASTIC WATER TRANSPORT IN ROOTS: E. Steudle and K. Ranathunge Section 3: ION UPTAKE FROM AND LOADING INTO THE APOPLAST: CHARACTERISATION OF CHANNEL PROPERTIES AND RELEVANCE FOR THE NUTRITION OF PLANTS LONG DISTANCE TRANSPORT IN PLANTS: TOWARDS ANALYSES OF REGULATORY INTERACTIONS BETWEEN MEMBRANE TRANSPORT SYSTEMS AND CELL WALL IONIC ATMOSPHERE IN VASCULAR TISSUES: H. Sentenac THE ROLE OF POTASSIUM IN WOOD FORMATION OF POPLAR: J. Fromm and R. Hedrich TRANSPORT CHARACTERISTICS OF ION CHANNELS AS INFLUENCED BY APOPLASTIC PROPERTIES: P. Ache and R. Deeken ION UPTAKE FROM THE XYLEM INTO THE SYMPLASM OF THE MAIZE LEAF: M. Abshagen-Keunecke and U.-P. Hansen LOADING OF IONS INTO THE XYLEM OF THE ROOT: B. Kohler and K. Raschke Section 4: THESIGNIFICANCE OF THE APOPLAST AS A COMPARTMENT FOR LONG-DISTANCE TRANSPORT NEW TOOLS TO EXPLORE THE APOPLAST: F.W. Bentrup ON-LINE MEASUREMENTS OF ION RELATIONS IN THE XYLEM SAP OF INTACT PLANTS: L.H. Wegner, H. Schneider and U. Zimmermann DYNAMIC AND NUTRIENT FLUXES IN THE XYLEM: F. GILMER and U. Schurr RELATIONSHIP BETWEEN APOPLASTIC NUTRIENT CONCENTRATIONS AND THE LONG-DISTANCE TRANSPORT OF NUTRIENTS IN THE RICINUS COMMUNIS L. SEEDLING: E. Komor, G. Orlich and H. Bauer-Ruckdeschel LONG-DISTANCE WATER TRANSPORT UNDER CONTROLLED TRANSPIRATIONAL CONDITIONS: MINIMAL-INVASIVE INVESTIGATIONS BY MEANS OF PRESSURE PROBES AND NMR IMAGING: H. Schneider, L.H. Wegner, A. Haase and U. Zimmermann CHANGES IN COMPOSITION OF THE XYLEM SAP AS WELL AS IN ION FLUXES IN POPULUS TREMULA X ALBA L. XYLEM IN DEPENDENCE ON EXOGENOUS FACTORS: S. Siebrecht, G. Fiebelkorn and R. Tischner Section 5: ION RELATIONS IN THE APOPLAST OF LEAVES ION DYNAMICS IN THE APOPLAST OF LEAF CELLS: Z. Rengel PROBING APOPLASTIC ION RELATIONS IN VICIA FABA AS INFLUENCED BY NUTRITION AND GAS EXCHANGE: H.H. Felle and S. Hanstein THE ROLE OF THE LEAF APOPLAST IN MANGANESE TOXICITY AND TOLERANCE IN COWPEA (VIGNA UNGUICULATA L. WALP): M.M. Fecht-Christoffers, P. Maier, K. Iwasaki, H.P. Braun and W.J. Horst INTERACTION BETWEEN PHLOEM TRANSPORT AND APOPLASTIC SOLUTE CONCENTRATIONS: G. Lohaus INVESTIGATIONS OF THE MECHANISMS OF LONGDISTANCE TRANSPORT AND ION DISTRIBUTION IN THE LEAF APOPLAST OF VICIA FABA L.: W. Merbach, D. Luttschwager and K. Huve THE DYNAMICS OF IRON IN THE LEAF APOPLAST: M. Nikolic and V. Romheld SELF-REPORTING ARABIDOPSIS THALIANA EXPRESSING pH- AND [CA2+]- INDICATORS UNVEIL APOPLASTIC ION DYNAMICS: C. Plieth, D. Gao, M.R. Knight, A.J. Trewavas and B. Sattelmacher Section 6: THE APOPLAST COMPARTMENT FOR PLANT-MICROBE INTERACTIONS CONSTRAINTS FOR ENDOPHYTIC BACTERIA: T. Hurek THE APOPLAST OF NORWAY SPRUCE (PICEA

Influence of Nitrogen and Potassium Supply on Contents of Acrylamide Precursors in Potato Tubers and on Acrylamide Accumulation in French Fries

ABSTRACT Fried potato products may accumulate substantial amounts of acrylamide due to high precursor contents, namely reducing sugars and asparagine. In a two-factorial experiment increasing N supply, increased the contents of reducing sugars in most cases, and resulted in higher contents of free amino acids. α -amino-N, which was tightly correlated with the contents of free amino acids, can be regarded a suitable rapid test for free asparagine for a given variety. Increasing K addition always raised the citrate contents, but lessened the contents of reducing sugars. Selected treatments were processed into French fries. Highest acrylamide contents were observed in tubers grown with high N and inadequate K supply, which also contained the highest contents of precursors. The experiment clearly demonstrates that nutrient supply has significant impact on the contents of acrylamide precursors and thus for the acrylamide formation during frying.

Influence of Nitrogen Nutrition on Tuber Quality of Potato with Special Reference to the Pathway of Nitrate Transport into Tubers

Abstract The influence of nitrogen (N) nutrition on tuber quality of potato (Solanum tuberosum L.), i.e., specific gravity, starch, nitrate, and protein content as well as ascorbic acid content was investigated in a pot experiment. As expected, specific gravity and starch content decreased with increasing fertilizer rates. Protein and especially nitrate content were positively related to nitrogen fertilization, while the effect on l-ascorbic acid content was relatively small. Only at the highest N level, which led to drastic yield depressions (3.8 g N pot−1), l-ascorbic acid content was significantly reduced. Since is considered phloem-immobile and xylem transport into the tubers is restricted (because of the tubers low transpiration rate), the pathway of nitrate translocation into the tubers is unclear. For Ca2+, a direct uptake from the soil solution by the tuber surface is well documented. In order to check whether this pathway may also be of importance for , potato plants were cultivated in solution culture. The growing tubers were wrapped with paper tissue soaked with Ca(15NO3)2-labelled tuber medium, while contact of the tubers with the nonlabeled liquid growth medium was strictly avoided. 15N-content of tubers was measured on a mass spectrometer. The experiment demonstrated that with high concentration at the tuber surface, up to 40% of total tuber content can be taken up through the tuber skin.

Response of Lowland and Aerobic Rice to Ammonium and Nitrate Supply During Early Growth Stages

ABSTRACT Decreasing fresh water availability has intensified the search for alternative rice cultivation systems with reduced water input, but most evidence suggests negative effects on growth of lowland (LL) rice cultivars. Yield in such production systems may be improved by selection of adapted aerobic ‘Han Dao’ (HD) rice cultivars. Lowland and HD rice were compared under sole nitrate or ammonium supply as well as under mixed supply of both nitrogen (N) forms during the seedling and tillering stage; pronounced differences were found in response to the supplied N form. Shoot dry mass (DM) of HD was significantly lower than that of LL under sole and predominant ammonium supply, whereas LL showed the opposite trend, with significantly lower shoot DM under sole-nitrate supply. Nitrogen concentration of LL rice under sole-nitrate supply was significantly lower compared with other treatments at tillering stage. Han Dao rice had a significantly higher potassium (K) concentration than LL rice under sole-nitrate supply, while the opposite result was observed under sole-ammonium supply. At seedling stage, the portion of N that was taken up from nitrate-N varied from 30% to 40% in HD and LL rice in treatments 75N/25A and 50N/50A, while at both growth stages, predominant ammonium supply resulted in a lower portion (20%) of nitrate-derived N in LL than in HD rice. The portion of nitrate-derived N increased at tillering stage (from 40% to 70%). These results further illustrate a synergistic effect of co-provision of nitrate and ammonium on total N fluxes compared with supply of sole nitrate or sole ammonium. It was concluded that the interaction between N form and tiller formation during early growth stages deserves strong attention for the identification of aerobic rice cultivars.

Light-induced cytosolic calcium transients in green plant cells. ll. The effect on a K+ channel as studied by a kinetic analysis in Chara corallina

Abstract. The fluorescent dye chlorotetracycline was used to study the relationship between the light-induced decrease in cytosolic free calcium concentration, [Ca2+]c, and its effect on ion transport at the plasma membrane in the giant cells of Chara corallina Klein ex Willd. A kinetic analysis of the simultaneously measured light-induced changes in membrane potential and in [Ca2+]c led to the same time constant of about 40 s. The reversal potential of the light effect on membrane potential was in agreement with the dominant role of a K+ channel in the plasma membrane. Thus, the experiments reported here provide evidence for the following light-driven signal transduction chain from the chloroplasts to K+ transport of the plasma membrane: (i) light causes an uptake of Ca2+ into the chloroplasts, (ii) this causes a decrease in cytosolic [Ca2+]c, (iii) this leads to a decrease in the activity of a K+ channel. The results also initiated a re-analysis of previously published data of the light effect on the velocity of cytosolic streaming and supported the hypothesis that Ca2+ fluxes coming out of the chloroplasts upon darkening cause a Ca2+-induced phosphorylation of myosin, which slows down cytoplasmic streaming.