Ulrich Lüttge

Progress in Botany

In the past 55 years, enormous scientific progress was made in many fields of plant physiology and plant biochemistry. Throughout these years, our knowledge on the photosynthetic light processes, the chemical composition and H.K. Lichtenthaler (*) Botanical Institute 2 (Molecular Biology and Biochemistry of Plants), Karlsruhe Institute of Technology (KIT), University Division, Kaiserstr. 12, 76131 Karlsruhe, Germany e-mail: hartmut.lichtenthaler@kit.edu

Salinity : environment - plants - molecules

Acknowledgements. Introduction. A: Environment. 1. Global impact of salinity and agricultural ecosystems M.G. Pitman, A. Lauchli. 2. Salinity in the soil environment K.K. Tanji. 3. Salinity, halophytes and salt affected natural ecosystems S.-W. Breckle. B: Organisms. 4. Adaptation of halophilic Archaea to life at high salt concentrations A. Oren. 5. Adaptation of the haloterant alga Dunaliella to high salinity U. Pick. 6. Mangroves U. Luttge. C: Mechanisms. 7. Ultrastructural effects of salinity in higher plants H.-W. Koyro. 8. Intra- and inter-cellular compartmentation of ions - a study in specificity and plasticity G. Wyn Jones, J. Gorham. 9. Salinity, osmolytes and compatible solutes D. Rhodes, et al. 10. Sodium-calcium interactions under salinity stress G.R. Cramer. 11. Salinity and nitrogen nutrition W.R. Ullrich. 12. Pressure probe measurements of the driving forces for water transport in intact higher plants: effects of transpiration and salinity U. Zimmermann, et al. 13. Salinity, growth and phytohormones R. Munns. 14. The adaptive potential of plant development: evidence from the response to salinity G.N. Amzallag. D: Photosynthesis. 15. Influence of salinity on photosynthesis of halophytes C.E. Lovelock, M.C. Ball. 16. Performance of plants with C4-carboxylation modes of photosynthesis under salinity U. Luttge. 17. Induction of Crassulacean acid metabolism by salinity -- molecular aspects H.J. Bohnert.E: Molecules. 18. Function of membrane transport systems under salinity: plasma membrane L. Reinhold, M. Guy. 19. Function of membrane transport systems under salinity: tonoplast M. Binzel, R. Ratajczak. 20. Genetics of salinity responses and plant breeding J. Gorham, G.Wyn Jones. 21. Halotolerance genes in yeast R. Serrano. 22. The long and winding road to haloterance genes A. Maggio, et al. Index.

Seasonal shift from C3 photosynthesis to Crassulacean Acid Metabolism in Mesembryanthemum crystallinum growing in its natural environment

SummaryChanges in δ13C value, diurnal malate content, water content and Na+, K+ and Cl- content of the annual Mesembryanthemum crystallinum (Aizoaceae) were followed in a natural population on a coastal cliff at the Mediterranean Sea shore close to Caesarea (Israel). Plants germinated in the middle of the rainy season in December 1976/January 1977. Diurnal malate fluctuations in the leaves were not detected until the end of March. Later on, at the start of the dry season, pronounced diurnal changes in malate developed. This was correlated with a progressive change in δ 13C value from about -26‰ to about -16‰ which is consistent with a change from normal C3 photosynthetic CO2 fixation to a predominantly nocturnal CO2 assimilation pattern involving Crassulacean Acid Metabolism.

Day-night changes in leaf water relations associated with the rhythm of crassulacean acid metabolism in Kalanchoë daigremontiana.

A study was made of the day-night changes under controlled environmental conditions in the bulk-leaf water relations of Kalanchoë daigremontiana, a plant showing Crassulacean acid metabolism. In addition to nocturnal stomatal opening and net CO2 uptake, the leaves of well-watered plants showed high rates of gas exchange during the whole of the second part of the light period. Measurements with the pressure chamber showed that xylem tension increased during the night and then decreased towards a minimum at about midday; a significant increase in xylem tension was also seen in the late afternoon. Cell-sap osmotic pressure paralleled leaf malate content and was maximum at dawn and minimum at dusk. The relationship between these two variables indicated that the nocturnally synthesized malate was apparently behaving as an ideal osmoticum. To estimate bulk-leaf turgor pressure, values for water potential were derived by correcting the pressurechamber readings for the osmotic pressure of the xylem sap. This itself was found to depend on the malate content of the leaves. Bulk-leaf turgor pressure changed rhythmically during the day-night cycle; turgor was low during the late afternoon and for most of the night, but increased quickly to a maximum of 0.20 MPa around midday. In water-stressed plants, where net CO2 uptake was restricted to the dark period, there was also an increase in bulk-leaf turgor pressure at the start of the light period, but of reduced magnitude. Such changes in turgor pressure are likely to be of considerable ecological importance for the water economy of crassulacean-acid-metabolism plants growing in their natural habitats.

Mineral Nutrition: Divalent Cations, Transport and Compartmentation

“Heavy metals” and “trace elements” were last reviewed in this series by Lonera-gan (1982) and Fe was also covered in Luttge and Clarkson (1985). The physiology and ecophysiology of “heavy metal plants” is discussed by Ernst (1982). In this review we will discuss the membrane transport and internal compartmentation of divalent cations in the light of what has been discovered about calcium. We do this without exhaustive reference to the frequently reviewed calcium literature (Evans 1988). The divalent cations encountered by plants make up a diverse group of elements some of which have major nutrient functions, others have well-recognized roles as trace elements, others such as nickel and cobalt are suspected trace elements while others, frequently concentrated by the activities of man, are highly toxic to most plants. To introduce some cohesion into the review, we have concentrated on possible ways in which their activities in the cytoplasm might be controlled. We have excluded Fe2+ from this review because of the specialized nature of its absorption by roots.

Early Salt Stress Effects on the Differential Expression of Vacuolar H+-ATPase Genes in Roots and Leaves of Mesembryanthemum crystallinum

In Mesembryanthemum crystallinum, the salt stress-induced metabolic switch from C3 photosynthesis to Crassulacean acid metabolism is accompanied by major changes in gene expression. However, early effects of salt exposure (i.e. prior to Crassulacean acid metabolism induction) on genes coding for vacuolar transport functions have not yet been studied. Therefore, the expression of vacuolar H+-ATPase genes was analyzed in different organs of 4-week-old plants stressed with 400 mM NaCl for 3, 8, or 24 h. Partial cDNAs for the subunits A, B, and c were cloned and used as homologous probes for northern blot analysis. In control plants, the mRNA levels for the different subunits showed organ-specific differences. In fully expanded leaves, subunit c mRNA was very low but increased transiently during the light period. Plant organs also differed in their salt-stress response. In roots and young leaves, mRNA levels for all three subunits increased about 2-fold compared to control plants, whereas in fully expanded leaves only subunit c mRNA responded to salt. The results indicate that the expression of vacuolar H+-ATPase genes does not always involve a fixed stoichiometry of mRNAs for the different subunits and that the mRNA level for subunit c is particularly sensitive to developmental and environmental changes.

Separation and purification of the tonoplast ATPase and pyrophosphatase from plants with constitutive and inducible Crassulacean acid metabolism

Tonoplast vesicles were isolated from Kalanchoe daigremontiana Hamet et Pierrer de la Bâthie and Mesembryanthemum crystallinum L., exhibiting constitutive and inducible crassulacean acid metabolism (CAM), respectively. Membrane-bound proteins were detergent-solubilized with 2% of Triton X-100. During CAM induction in M. crystallinum, ATPase activity increases four-fold, whereas pyrophosphatase activity decreases somewhat. With all plants, ATPase and pyrophosphatase could be separated by size-exclusion chromatography (SEC, Sephacryl S 400), and the ATPase was further purified by diethylaminoethyl-ion-exchange chromatography. Sodium-dodecyl-sulfate electrophoresis of the SEC fractions from K. daigremontiana containing maximum ATPase activity separates several protein bands, indicating subunits of 72, 56, 48, 42, 28, and 16 kDa. Purified ATPase from M. crystallinum in the C3 and CAM states shows a somewhat different protein pattern. With M. crystallinum, an increase in ATP-hydrolysis and changes in the subunit composition of the native enzyme indicate that the change from the C3 to the CAM state is accompanied by de-novo synthesis and by structural changes of the tonoplast ATPase.

Specific regulation of SOD isoforms by NaCl and osmotic stress in leaves of the C3 halophyte Suaeda salsa L.

The halophyte Suaeda salsa L., exposed to different NaCl concentrations (100 and 400 mmol/L) and polyethylene glycol (isoosomotic to 100 mmol/L NaCl) containing nutrient solutions under normal or K+-deficient conditions for 7 days, was used to study effects of NaCl salinity and osmotic stress on chlorophyll content, chlorophyll fluorescence characteristics, malonedialdehyde (MDA) content, and superoxide dismutase (SOD) isoform activities. Photosynthetic capacity was not decreased by NaCl treatment, indicating that S. salsa possesses an effective antioxidative response system for avoiding oxidative damage. Seven SOD activity bands were detected in S. salsa leaf extracts, including an Mn-SOD and several isoforms of Fe-SOD and CuZn-SOD. It turned out that NaCl salinity and osmotic stress lead to a differential regulation of distinct SOD isoenzymes. This differential regulation is suggested to play a major role in stress tolerance of S. salsa.

Midday depression in savanna trees: coordinated adjustments in photochemical efficiency, photorespiration, CO2 assimilation and water use efficiency

High irradiances, high air temperatures and low relative humidities characterize the seasonal savannas of central Brazil, locally known as cerrados. In the present study, we investigated the implications to photoprotection of diurnal adjustments in photochemical and non-photochemical processes in five cerrado woody species that differed in photosynthetic capacity and in the duration and extension of the midday depression of photosynthesis. We also evaluated the contribution of photorespiration to minimize the danger of photoinhibition and the potential carbon costs of the operation of this mechanism in response to changes in irradiance levels. Notwithstanding the large differences in diurnal patterns of photosynthesis and in stomatal conductance, four out of the five species showed a tight common linear relationship between net CO2 assimilation rates and transpiration over the large range of environmental conditions that prevailed during typical sunny days at the end of the rainy season. Large reversible decreases in photochemical efficiency were compensated by proportional increases in non-photochemical processes related to photoprotection, irrespective of the prevailing irradiance levels and degree of stomata closure. Light response curves were used to evaluate the relative contribution of photorespiratory CO2 production to electron flow in response to changes in irradiance levels. A large percentage of the electron flow was used to drive photorespiration in light-saturated leaves. In conclusion, an efficient control of photochemical and non-photochemical quenching and adjustments in the partition of electron flow between assimilative and non-assimilative processes alleviated the danger of photoinhibition. However, the results also suggest that losses in potential carbon gain because of high photorespiratory costs could impose strong limitations on leaf carbon balance of cerrado woody species.

Über die Zusammensetzung des Nektars und den Mechanismus seiner Sekretion. I

1. Der Gehalt einiger floralen und extrafloralen Nektare an K+, Na+, Ca++ und Mg++ wurde gepruft. Zum Vergleich werden Ergebnisse von Phosphatbestimmungen und von Analysen der ninhydrinpositiven Substanzen angegeben. 2. Die molaren Verhaltnisse losl. Mg/losl. Ca und Gesamt-Mg/Gesamt-Ca wurden in verschiedenen Nektargeweben und vergleichsweise in anderen, den Nektarien moglichst benachbarten Pflanzenteilen untersucht. Das Verhaltnis losl. Mg/losl. Ca ist in den Nektarien desrs hoch. Daraus werden Ruckschlusse aus die Bedeutung des Mg++, bei der Nektarsekretion gezogen.