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  • 1
    Digitale Medien
    Digitale Medien
    Endogenous ethylene formation and the development of the alternative pathway in potato tuber discs (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 65 (1985), S. 0 
    Details
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Callus-forming discs from potato (Solanum tuberosum L. cv. Bintje) tubers grown on a nutrient medium containing an auxin and a cytokinin show both a higher ethylene formation and a higher capacity of the mitochondrial alternative pathway than nongrowing discs (on the same medium without auxin and cytokinin). Addition of 1-ami-nocyclopropane-1-carboxylic acid (ACC) to the nutrient medium of non-growing discs results in an enhancement of the ethylene formation as well as the alternative pathway capacity. In callus-forming tissue, the levels of both these parameters can be suppressed by adding aminoethoxyvinylglycine (AVG) to the nutrient medium without affecting growth. The effects on state 3-respiration of ACC (increase) and AVG (decrease) are relatively small. These results suggest that the alternative pathway capacity is controlled to a considerable extent by the endogenous ethylene formation of the tissues.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1399-3054.1985.tb02359.x
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  • 2
    Digitale Medien
    Digitale Medien
    Carbon dioxide and ethylene interactions in tulip bulbs (2002)
    Oxford, UK : Blackwell Science, Ltd
    Physiologia plantarum 114 (2002), S. 0 
    Details
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The effect of CO2 on ethylene-induced gummosis (secretion of polysaccharides), weight loss and respiration in tulip bulbs (Tulipa gesneriana L.) was investigated. A pretreatment with 1-MCP prevented these ethylene-induced effects, indicating that ethylene action must have been directed via the ethylene receptor. Treatment with 0.3 Pa ethylene for 2 days caused gummosis on 50% of the total number of bulbs of cultivar Apeldoorn, known to be sensitive for gummosis. Addition of CO2 (10 kPa) reduced the ethylene-induced gummosis to 18%. In a second experiment the influence of ethylene and CO2 on respiration and FW loss of bulbs of the cultivar Leen van der Mark was studied. A range of ethylene partial pressures (0.003–0.3 Pa) was applied continuously for 29 days. Ethylene caused a transient peak in O2 consumption rate during the first days after the start of application. The relation between O2 consumption rate and ethylene partial pressure could be described by Michaelis-Menten kinetics. Respiratory peaks were reduced by CO2. This inhibition by CO2 could not totally be due to competition with ethylene at the receptor binding-site, as was indicated by the use of an O2 consumption model. Pre-treatment of bulbs with 1-MCP and subsequent exposure to CO2 showed that CO2 could influence respiration irrespective of any interaction with ethylene. Ethylene and CO2 both stimulated weight loss. The effect of combined treatments of ethylene and CO2 on weight loss was at least as strong as the sum of the separate effects, which implies that competition between ethylene and CO2 at the receptor binding-site was unlikely.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1399-3054.2002.1140219.x
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  • 3
    Digitale Medien
    Digitale Medien
    Hydroxamate-activated peroxidases in potato tuber callus. Interaction with the determination of the cytochrome and the alternative pathways (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 70 (1987), S. 0 
    Details
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: In potato (Solatium tuberosum L. cv. Bintje and Doré) callus a very active hydrox-amate-stimulated NADH-dependent O2-uptake develops during the growth of the callus, which is caused by a peroxidase. More than 95% of the peroxidase activity is found in the 40000 g supernatant. The total activity may be as high as 1000 times the respiratory acitivity of the callus tissue. At least two fractions, obtained by Sephadex gel filtration, can be distinguished showing this peroxidase activity, one of about 15 kDa and one 〉 50 kDa.The main properties of both fractions are:a) Hydroxamate at 0.2–0.5 mM gives half-maximal stimulation. Maximal stimulation is observed with 1–3 mM benzhydroxamate (BHAM) and 1–15 mM salicylhydroxamate (SHAM). Higher concentrations, especially of BHAM, give less or no stimulation.b) Hydroxamates are not consumed during the reaction.c) Both NADH and NADPH can serve as the electron donor for the reaction. The affinity for NAD(P)H is very low (Km near 10 mM). In the absence of hydroxamates NAD(P)H is only slowly oxidized, with an even lower affinity.d) The peroxidase can carry out two reactions: an O2-consuming and a H2O2-consuming reaction. In both reactions one NAD(P)H is consumed. In the first reaction H2O2 is formed which can be consumed in the second reaction, resulting in an overall stoichiometry of 2 NADH consumed for each O2 molecule and in the production of H2O.e) The reaction is completely blocked by cyanide, superoxide dismutase (EC 1.15.1.1) and (excess) catalase (EC 1.11.1.6), but not by antimycin A or azide. This peroxidase-mediated O2-uptake might interfere with respiratory measurements. In experiments with isolated mitochondria this interference can be prevented by the addition of catalase to the reaction mixture. The use of high concentrations of hydroxamate is not allowed because of inhibitory effects on the cytochrome pathway. In intact callus tissue hydroxamates only stimulate O2-uptake in the presence of exogenous NADH. In vivo the peroxidase does not appear to function in O2-uptake, probably because of its localization (at least partly in the cell wall) and/or its low affinity for NADH. The use of hydroxamates in the determination of cytochrome and alternative pathway activity is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1399-3054.1987.tb08693.x
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  • 4
    Digitale Medien
    Digitale Medien
    The regulation of respiration and growth of potato tuber callus by endogenous ethylene. Suppression of ethylene action by 2,5-norbornadiene (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 70 (1987), S. 0 
    Details
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The growth (fresh and dry weight increase) of potato tuber (Solanum tuberosum L. cv. Bintje) callus discs was stimulated by incubation in air with 500 ppm 2,5-norbornadiene (NBD, a competitive inhibitor of ethylene action) and inhibited by incubation in air with 4 000 ppm NBD. Ethylene formation by the callus was stimulated by NBD. The development of the alternative pathway, measured in isolated mitochondria was inhibited by NBD in a concentration-dependent way. The alternative pathway capacity, measured in vivo, was inhibited by 4 000 ppm NBD, but not by 500 ppm. Uninhibited in vivo respiration, which consists of cytochrome path activity and alternative path activity, was stimulated by the treatment with 500 ppm NBD. The main contribution to this stimulation was made by the cytochrome pathway. In 4 000 ppm NBD-treated callus, uninhibited respiration seemed to be unaffected as a consequence of an inhibited cytochrome path activity, which was compensated by a stimulated alternative path activity. Both in 500 and 4 OIK) ppm NBD-treated callus the alternative path activity in vivo was stimulated.The regulatory role for endogenous ethylene in potato tuber callus is discussed in relation to: 1) The induction of respiratory pathways, 2) the supply of reduction equivalents in vivo and 3) growth.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1399-3054.1987.tb04324.x
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  • 5
    Digitale Medien
    Digitale Medien
    The effects of abscisic acid on growth and respiratory characteristics of potato tuber tissue discs (1988)
    Springer
    Plant growth regulation 7 (1988), S. 101-116 
    Details
    ISSN: 1573-5087
    Schlagwort(e): potato ; callus ; respiration ; abscisic acid ; mitochondria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Incubation of potato tuber tissue discs on B5 medium supplemented with 1-naphtyl-acetic acid (NAA) led to callus formation, irrespective of the presence of kinetin; without NAA no callus formation occurred. Incubation in the presence of abscisic acid (ABA) reduced the increases in fresh weight and dry weight both in callus-forming and in non-callus-forming tissue. Mitochondrial respiration was lowered by ABA as well. The induction of the alternative, CN-resistant pathway was inhibited by the presence of ABA, especially in mitochondria from non-callus-forming tissue. The in vivo respiration of the callus-forming tissue was higher than that of the non-callus-forming tissue. Total respiration, cytochrome pathway activity and the capacity of the alternative pathway were all lowered in callus-forming tissue by treatment with ABA. The in vivo activity of the alternative pathway was low in all tissue types, especially after ABA-treatment. The slight stimulation by hydroxamates of the oxygen uptake of callus-forming tissue incubated on medium with NAA and ABA indicates the involvement of a hydroxamate-activated peroxidase in the oxygen uptake of this tissue; this peroxidase seemed not to participate in the oxygen uptake of the other tissues types. In non-callus-forming tissue the oxygen uptake of ABA-treated tissue was very low and almost completely resistant to the combined addition of inhibitors of both the cytochrome and the alternative pathway, indicating that the in vivo activity of the mitochondria in the oxygen uptake of the tissue was very low. The possible causes for this ABA-effect are discussed. In non-callus-forming tissue the treatment with ABA creates a situation which is comparable with that observed in intact potato tubers. This situation is characterized by a tissue respiration lower than that of the isolated mitochondria and an alternative pathway capacity that is low or absent.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00025205
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