J. Feierabend

Bio: J. Feierabend is an academic researcher from Ruhr University Bochum. The author has contributed to research in topics: Kinetin & Cytokinin. The author has an hindex of 13, co-authored 17 publications receiving 613 citations. Previous affiliations of J. Feierabend include University of Göttingen & Goethe University Frankfurt.

Biochemical differentiation of plastids and other organelles in rye leaves with a high-temperature-induced deficiency of plastid ribosomes.

Abstract: 1. In developing rye (Secale cereale L.) leaves the formation of plastidic ribosomes was selectively prevented in light as well as in darkness, when the seedlings were grown at an elevated temperature of 32° instead of 22° where normal development ocurred. Plastid ribosome deficient parts of lightgrown leaves were chlorotic at 32°. — 2. At both temperatures the leaves contained under all conditions (light or dark, on H2O or nutrient solution) equal or very similar amounts of total amino nitrogen. In light, the contents of total protein and dry weight were lower at 32° than at 22°, especially when the plants were grown on nutrient solution. — 3. Mitochondrial marker enzymes had normal or even higher activities in 32°-grown leaves. Respiration rates were similar for segments of leaves grown on water in light either at 32° or at 22° but by 20–30% lower for 32°-grown plants when they had been raised in darkness or on nutrient solution. In contrast to 22°-grown tissue, respiration of 32°-grown leaf segments was rather insensitive to KCN. Comparative inhibitor studies indicated the presence of both the cyanide-sensitive and the cyanide-insensitive pathway of respiration in 32°-grown leaves. — 4. Leaf microbody marker enzymes were present in leaves grown at 32°. From chlorotic parts of 32°-light-grown leaves a typical microbody fraction was isolated on sucrose densitygradients. — 5. Leaves of seedlings grown at 32° contained only very low levels of ribulosediphosphate carboxylase activity and of fraction I protein. Photosynthetic 14CO2-fixation of such leaves was only a few per cent of that observed in normal leaves, and no photosynthetic oxygen evolution was observed in chlorotic leaf segments. However, ten other soluble enzymes which are exclusively or partially localized in chloroplasts reached high activities under all conditions at 32° (Table 4). — 6. From chlorotic parts of 32°-light-grown leaves as well as from etiolated 32°-grown leaves a fraction of intact plastids was isolated and purified by sucrose gradient centrifugation which contained several soluble chloroplast enzymes. From the results we conclude that cytoplasmic protein synthesis must contribute a functional chloroplast envelope including the mechanism for the recognition and uptake of chloroplast proteins which are synthesized on cytoplasmic ribosomes.

Developmental studies on microbodies in wheat leaves : III. On the photocontrol of microbody development.

Abstract: 1. In etiolated wheat (Triticum aestivum L.) leaves, the development of the microbody enzymes catalase, hydroxypyruvate reductase, and glycolate oxidase was specifically stimulated by short treatments of the seedlings with red light, although the increases were less than observed after treatment with continuous white light. A comparison of the effects of short red and far-red exposures indicated the involvement of phytochrome. 2. Continuous far-red light treatments also enhanced the development of microbody enzymes. Catalase activity continued to increase at a high rate even after return from a prolonged far-red illumination to darkness, while the increase in the activities of glycolate oxidase and hydroxypyruvate reductase fell to the dark rates when the tissue was removed from the light. However, even at higher intensities of continuous far-red light the microbody enzymes reached only considerably lower activities than in white light. During continuous irradiation of equal quantum flux, the microbody enzymes reached higher activities in red than in far-red light, but the highest activities were observed in blue light, which had similar effects as white light. The quantitative difference between the effects of prolonged red or blue light depended also on the seed material and growing conditions. In the presence of the herbicide 3-amino-1,2,4-triazole the increase of glycolate-oxidase activity was reduced in red light but was affected much less, if at all, in blue light. 3. Continuous irradiations with all three light qualities used (red, far-red, blue) influenced the properties of the microbody particles to form a distinct band sharply confined close to an equilibrium density of 1.25 g cm-3 on sucrose gradients which was not observed in preparations from plant material raised in complete darkness. In preparations from all light-grown plants a special peak in the activity profile of malate dehydrogenase was found in the microbody fraction while it was lacking on gradients from dark-grown leaves. The heights of the activities of malate dehydrogenase as well as of the other enzymes found in the microbody fractions from plants grown in either far-red, red, or blue light differed in the same way as did the activities from total leaf homogenates. 4. Glycolate oxidation by segments of intact leaf tissue was higher with tissue from light- than from dark-grown plants, but after light treatments of different spectral quality its magnitude did not correspond to the extractable activities of glycolate oxidase.

Der Einfluß von Cytokininen auf die Bildung von Photosyntheseenzymen in Roggenkeimlingen

Abstract: 1. Factors were investigated which control the formation of photosynthetic enzymes during germination. Enzymes of the reductive pentose phosphate cycle like carboxydismutase (EC 4.1.1.39) and NADP-dependent glyceraldehydephosphate dehydrogenase (EC 1.2.1.9.) are formed in the primary leaves of dark-grown rye seedlings. The rate of their synthesis is determined by the level of cytokinins. This rate can be increased by treatment of normal seedlings with kinetin. After application of kinetin to dark-grown seedlings, the investigated enzymes finally reach the same activity as they do in untreated light-grown plants. The formation of these photosynthetic enzymes can be strongly reduced by excision of the roots early in the development, a treatment which is known to lower the supply of cytokinins. A high rate of enzyme formation can be restored by feeding kinetin to rootless seedlings. Neither adenosine nor gibberellic acid have this effect on enzyme formation. 2. Changes in the content of cytokinins preferentially influence the formation of the investigated photosynthetic enzymes. Some cytoplasmic enzymes are not affected by the decrease of the cytokinin level which is achieved by excision of the roots. At the beginning of germination only cytoplasmic enzymes are promoted by application of kinetin, whereas in later stages, after 96 hours of germination, only the formation of photosynthetic enzymes is increased. The formation of photosynthetic and cytoplasmic enzymes seem to differ in their cytokinin requirements. 3. Cytokinins seem to be necessary for the formation of enzymes of the reductive pentose phosphate cycle. However, the cytokinins do not alter the time of appearance of these enzymes. Also the suppressing action which is exerted on the formation of photosynthetic enzymes by low temperature cannot be prevented by the application of kinetin. The action of cytokinins probably does not induce the derepression of the genes, but the level of cytokinins determines the extent of the manifestation of the genes. 4. The formation of the photosynthetic enzymes is also promoted by phytochrome. Phytochrome and cytokinin act as independent factors in a multiplicative system. The rate of synthesis of these enzymes in the dark, which corresponds to the cytokinin level of the seedlings (rootless, normal or treated with kinetin) can be increased by a constant factor via the phytochrome system by continuous irradiation with far-red light. In the case of carboxydismutase this factor is nearly 2. 5. After excision of the roots carboxydismutase and NADP-dependent glyceraldehydephosphate dehydrogenase reach higher activity in red and blue light than in far-red light, under which no chlorophyll is formed. In this case formation of carboxydismutase in red and blue light seems to proceed in close correlation with chlorophyll synthesis.

Comparative analysis of the action of cytokinin and light on the formation of ribulosebisphosphate carboxylase and plastid biogenesis

Abstract: The role of cytokinin in plastid biogenesis was investigated in etiolated rye leaves (Secale cereale L.) and compared with the effect of white light. Cytokinin deficiency of the leaves was induced by early excision of the seedling roots and reversed by the application of kinetin. The cytokinin supply had a much greater influence on plastid biogenesis than on leaf growth in general. The activities of several chloroplastic enzymes were increased 200%–400% after kinetin treatment of cytokinin-depleted leaves. The activity of ribulose-1,5-bisphosphate carboxylase (EC 4.1.1.39) and the amount of fraction-I protein even showed a sevenfold increase. In cytokinin-depleted leaves the development of ribulose-1,5-bisphosphate carboxylase and NADP-glyceraldehydephosphate dehydrogenase was specifically, and markedly inhibited by actinomycin D. The inhibition was partially or even completely overcome after treatment with kinetin. However, under all conditions, RNA synthesis of the leaves, was only partially inhibited by actinomycin D. According to immunologic studies, all dark-grown leaves, in addition to the complete enzyme, contained an excess of free small subunit of ribulose-1,5-bisphosphate carboxylase that was absent in mature light-grown leaves. The most striking accumulation of free small subunit, protein occurred in cytokinin-depleted dark-grown leaves, indicating a deficiency of the plastidic synthesis of the large subunit. The capacity as well as the activity of plastidic protein synthesis was preferentially increased by cytokinin and light. Cytokinin increased, the amount of plastidic ribosomes per leaf and relative to the amount of cytoplasmic ribosomes. While the percentage of cytoplasmic ribosomes bound as polyribosomes was little affected by the cytokinin supply, the proportion of plastidic polyribosomes was increased from 11% to 18% after kinetin treatment of cytokinin-depleted leaves. In the light, the proportion of plastidic polyribosomes reached 39% of the total plastidic ribosomes.

Capacity for chlorophyll synthesis in heat-bleached 70S ribosome-deficient rye leaves.

Abstract: The leaves of young rye plants (Secale cereale L.) grown at 32° were deficient in chlorophyll and in chloroplastic rRNA as compared to those grown at 22°, which developed normally. Both chlorophyll accumulation and the formation of plastidic rRNA were largely restored at 32° when the plants were transfered several times for 1 h per day to 22°. In the chlorotic 32°-grown rye leaves the in vivo activity of δ-aminolevulinate synthetase was very low. Aminolevulinate dehydratase however, exhibited high activity in extracts from 32°-grown leaves and was localized in the plastid fraction isolated from the chlorotic leaf tissue. After application of δ-aminolevulinic acid to chlorotic parts of leaves growing at 32°, protochlorophyll(ide) was formed and accumulated in the dark. In the light, the protochlorophyll(ide) was photooxidized at 32°. The results suggest a cytoplasmic site of synthesis for the series of enzymes converting δ-aminolevulinate to protochlorophyll(ide). It is concluded that an inhibition of δ-aminolevulinate synthetase and the photooxidation of protochlorophyll(ide) or chlorophyll are responsible for the chlorosis of the leaves at 32°.

Photosynthetic Response and Adaptation to Temperature in Higher Plants

Abstract: INTRODUCTION 492 ECOLOGICAL ASPECTS OF PHOTOSYNTHETIC TEMPERATURE ADAPTATION 493 Photosynthetic Temperature Dependence in Thermally Contrasting Climates ........ 493 Photosynthetic Temperature Acclimation 497 Seasonal acclimation in natural habitats ...... ....... 497 Studies in controlled environments 499 THE MECHANISTIC BASIS FOR PHOTOSYNTHETIC RESPONSE AND ADAPTATION TO TEMPERATURE 504 Reversible Temperature Respon.ses 505 Stomata! effec� o� the . temJH!.rature response 0/ photo.rynthesis ......... ....... 505 Interacttons with /lght mtenslty 507 C, photo.rynthesis (lM photorespiration 507 C, photo.rynthesis 515 Comparison 0/ plants from contrasting thermol regimes ...... ...... 517 ["eversible Temperature Respon.ses 519 Low temperature sensitMty ....... 519 High temperature sensitivity 524 Adoptive responses in the heat stability 0/ the photosynthetic apparatus 530 CONCLUDING REMARKS 532

The presence of glutathione and glutathione reductase in chloroplasts: A proposed role in ascorbic acid metabolism.

Abstract: Both glutathione and an NADPH-dependent glutathione reductase are present in spinach (Spinacia oleracea L.) chloroplasts. It is proposed that glutathione functions to stabilise enzymes of the Calvin cycle, and it may also act to keep ascorbic acid in chloroplasts in the reduced form.

Tolerance of pea (Pisum sativum L.) to long‐term salt stress is associated with induction of antioxidant defences

Abstract: Using two cultivars of Pisum sativum L. with different sensitivity to NaCl, the effect of long-term (15 d) NaCl (70 m M) treatments on the activity and expression of the foliar ascorbate–glutathione cycle enzymes, superoxide dismutase isozymes and their mRNAs was evaluated and related to their ascorbate and glutathione contents. High-speed supernatant (soluble) fractions, enriched for cytosolic components of the antioxidant system, were used. In this fraction from the NaCl-tolerant variety (cv Granada), the activities of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), Mn-superoxide dismutase (Mn-SOD) and dehydroascorbate reductase (DHAR) increased, while CuZn-SOD activity remained constant. In the NaCl-sensitive plants (cv Challis), salinity did not produce significant changes in APX, MDHAR and GR activities. Only DHAR activity was induced in cv Challis, whereas soluble CuZn-SOD activity decreased by about 35%. Total ascorbate and glutathione contents decreased in both cultivars, but the decline was greater in NaCl-sensitive plants. This difference between the two cultivars was more pronounced when the transcript levels of some these enzymes were examined. Transcript levels for mitochondrial Mn-SOD, chloroplastic CuZn-SOD and phospholipid hydroperoxide glutathione peroxidase (PHGPX), cytosolic GR and APX were strongly induced in the NaCl-tolerant variety but not in the NaCl-sensitive variety. These data strongly suggest that induction of antioxidant defences is at least one component of the tolerance mechanism of peas to long-term salt-stress.

Antioxidant systems and o2.?/h2o2 production in the apoplast of pea leaves. its relation with salt-induced necrotic lesions in minor veins

Abstract: The present work describes, for the first time, the changes that take place in the leaf apoplastic antioxidant defenses in response to NaCl stress in two pea (Pisum sativum) cultivars (cv Lincoln and cv Puget) showing different degrees of sensitivity to high NaCl concentrations. The results showed that only superoxide dismutase, and probably dehydroascorbate reductase (DHAR), were present in the leaf apoplastic space, whereas ascorbate (ASC) peroxidase, monodehydroascorbate reductase (MDHAR), and glutathione (GSH) reductase (GR) seemed to be absent. Both ASC and GSH were detected in the leaf apoplastic space and although their absolute levels did not change in response to salt stress, the ASC/dehydroascorbate and GSH to GSH oxidized form ratios decreased progressively with the severity of the stress. Apoplastic superoxide dismutase activity was induced in NaCl-treated pea cv Puget but decreased in NaCl-treated pea cv Lincoln. An increase in DHAR and GR and a decrease in ASC peroxidase, MDHAR, ASC, and GSH levels was observed in the symplast from NaCl-treated pea cv Lincoln, whereas in pea cv Puget an increase in DHAR, GR, and MDHAR occurred. The results suggest a strong interaction between both cell compartments in the control of the apoplastic ASC content in pea leaves. However, this anti-oxidative response does not seem to be sufficient to remove the harmful effects of high salinity. This finding is more evident in pea cv Lincoln, which is characterized by a greater inhibition of the growth response and by a higher rise in the apoplastic hydrogen peroxide content, O(2)(.-) production and thiobarbituric acid-reactive substances, and CO protein levels. This NaCl-induced oxidative stress in the apoplasts might be related to the appearance of highly localized O(2)(.-)/H(2)O(2)-induced necrotic lesions in the minor veins in NaCl-treated pea plants. It is possible that both the different anti-oxidative capacity and the NaCl-induced response in the apoplast and in the symplast from pea cv Puget in comparison with pea cv Lincoln contributes to a better protection of pea cv Puget against salt stress.

Conservation and duplication of isozymes in plants.

Abstract: Many enzymes in plants have isozymes because the same catalytic reaction is often present in several subcellular compartments, most frequently the plastids and the cytosol. The number and subcellular locations of the isozymes appear to be highly conserved in plant evolution. However, gene duplication in diploid species and the addition of genomes in polyploid species have increased the number of isozymes.