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  • 1
    Electronic Resource
    Electronic Resource
    When plant teratomas turn into cancers in the absence of pathogens (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 83 (1991), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Habituated calli have long been classified as neoplasms together with tumors from different origins. The general opinion is that habituation is a reversible process with an epigenetic basis. This is probably true in most cases examined. However, we show here that there might be several degrees of habituation, which can be considered as steps of a neoplastic progression leading to cancerisation in the absence of an introduced oncogenic pathogen. Cell rejuvenation, loss of the capacity to organize meristematic centers, and loss of totipotency are proposed to define plant cancer through this neoplastic progression of a callus.Habituated tissues share many morphological and biochemical similarities with so-called vitreous shoots from micropropagation. Vitrification and hyperhydric malformations of shoots raised in vitro may be considered as steps of another neoplastic progression, which leads to cancerisation also in the absence of introduced oncogenic pathogens. In this case death of the whole organism occurs either through direct apex necrosis or indirectly, from the loss of the capacity for the primary meristems to function normally, which gives rise to completely anarchic structures. As in the animal kingdom, carcinogenesis in plants is the final result of a multistep process involving the irreversible conversion of a stem cell to a terminal-differentiation-resistant cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1991.tb02489.x
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  • 2
    Electronic Resource
    Electronic Resource
    Differential growth dependency of normal and habituated sugarbeet cell lines upon endogenous ethylene production and exogenous ethylene application (1998)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 103 (1998), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A fully habituated (auxin- and cytokinin-independent) nonorganogenic (HNO) sugarbeet (Beta vulgaris) callus produces very little ethylene as compared with a normal (N) hormone-requiring callus of the same strain. Both callus types react by growth changes to application of inhibitors of ethylene biosynthesis and ethylene action, of 1-aminocyclopropane-1-carboxylic acid (ACC) as the immediate precursor of ethylene, to transfer from light to darkness, and also to application of exogenous ethylene or an ethylene trapper. This indicates their growth dependency upon their endogenously biosynthesized ethylene and also their sensitivity to exogenous gas. However, the sensitivity was generally higher for the HNO callus producing naturally less ethylene. The weaker reaction of the HNO callus to the exogenous ethylene was attributed to its hyperhydric status (a water layer surrounding the cells). Because low ethylene production appears as a general characteristic of habituated cell lines, the causal and/or consequential relationships of this low ethylene production with other characteristics of habituated tissues (absence of exogenous hormones in the culture media, deficiency of cell differentiation, accumulation of polyamines in neoplastic tissues) are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1998.1030207.x
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  • 3
    Electronic Resource
    Electronic Resource
    A comparison between ethylene production, ACC and mACC contents, and hydroperoxide level in normal and habituated sugar beet calli (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 82 (1991), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In contrast to normal hormone, requiring sugar beet callus, habituated auxin- and cytokinin-independent callus of the same plant produces very little ethylene, contains less 1-aminocyclopropane-1-carboxylic acid (ACC) and malonyl-ACC (mACC), has a low capacity to convert ACC into ethylene and has lower levels of hydroperoxides. The low ethylene production is apparently controlled by the rate of ACC synthesis and conversion to mACC, as well as by the activity of the ethylene forming enzyme. The interactions between ethylene and polyamine metabolism are discussed, as well as the possible causal relation between the low level of ethylene and the low degree of differentiation of the habituated cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1991.tb02923.x
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  • 4
    Electronic Resource
    Electronic Resource
    The roles of calcium and manganese ions in the in vitro conversion of 1-aminocyclopropane-1-carboxylic acid to ethylene by lentil root membranes (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 79 (1990), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Ca2+ and Mn2+ activate the conversion of 1-aminocyclopropane-1-carboxylic acid (ACC) by root microsomes of Vicia lens as they do in other similar systems. The preparation of microsomes in the presence of Mn2+ greatly increases their ability to convert ACC into ethylene, without addition of Mn2+ in the reaction mixture. Ca2+ does not have this property. The effect could not be attributed to Mn2+ entrapping into membrane vesicles (sonication followed by repelleting had no effect) but, possibly, in part to Mn2+-mediated binding to microsomes of a soluble factor favouring the conversion of ACC to C2H4. Although no direct correlation could be established in vitro between ethylene-forming-enzyme (EFE) and peroxidase activities, some soluble peroxidases might be this soluble factor. Mn2+ favoured attachment to membranes of some peroxidase activity from the soluble fraction and from commercial HRP and lipoxygenase. This binding effect of Mn2+ cannot be readily distinguished from its role in the generation of a chain of free radicals and in redox mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1990.tb06738.x
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of in vitro storage at 4 °C on survival and proliferation of poplar shoots (1994)
    Springer
    Plant cell, tissue and organ culture 38 (1994), S. 65-67 
    Details
    ISSN: 1573-5044
    Keywords: cold storage ; micropropagation ; Populus tremula L. x Populus tremuloides L. ; shoot proliferation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Shoot explants of in vitro proliferating cultures of Populus tremula (L.) x Populus tremuloides (L.) were stored for three months at 4°C, in dark or light, in basal culture medium with or without 2-isopentenyladenine (2iP), and in rooting medium with naphthalene acetic acid. They were transferred to cold at different times after subculturing. One hundred percent of shoots survived all tested conditions, in spite of leaf browing and necrosis. After transfer to 24°C for 2 weeks and a normal multiplication cycle, the shoots proliferated at a rate similar to controls or at a higher rate in the case of shoots introduced into the cold 7 or 14 days after subculture and stored in dark on medium containing 2iP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034446
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  • 6
    Electronic Resource
    Electronic Resource
    Vitrification of carnation in vitro: Changes in ethylene production, ACC level and capacity to convert ACC to ethylene (1985)
    Springer
    Plant cell, tissue and organ culture 4 (1985), S. 215-223 
    Details
    ISSN: 1573-5044
    Keywords: vitrification ; in vitro culture ; ethylene ; 1-aminocyclopropane-1-carboxylic acid ; carnation ; Dianthus caryophyllus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Carnation tissue was allowed to vitrify in liquid culture and ethylene production, ACC content and capacity to convert ACC to ethylene were measured in comparison to tissue developing normally on solid medium. Flask atmospheres of liquid cultures accumulated ethylene at a higher rate during the first four days. Daily ethylene production by vitrifying material decreased later. Ethylene emission by vitrifying tissues always remained above controls when subcultured daily to fresh medium. Explants and microsomal preparations from vitrifying carnations converted ACC to ethylene at a higher degree from the first day in liquid medium. ACC level markedly increased in vitrifying tissues during the first two days of liquid culture. Raising the level of ethylene in the atmosphere of solid cultures did not induce vitrification symptoms nor did use of inhibitors of ethylene biosynthesis in liquid cultures prevent the process. The role of ethylene in vitrification is reappraised.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00040195
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  • 7
    Electronic Resource
    Electronic Resource
    The influence of ethylene on proliferation and growth of rose shoot cultures (1992)
    Springer
    Plant cell, tissue and organ culture 28 (1992), S. 175-181 
    Details
    ISSN: 1573-5044
    Keywords: axillary budding ; gaseous atmosphere ; micropropagation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ethylene accumulation in four different rose in vitro culture containers was evaluated. Multiplication rate was the highest, and axes most elongated, in the two containers where ethylene accumulation was limited. Pulse treatments of ethylene at various concentrations enhanced proliferation depending on concentration (5 ppm generally was the most favourable) and time of application, while reducing elongation of the shoots. An ethylene trap in the flask atmospheres of the cultures reduced rose shoot proliferation rate but increased elongation of the axes. Inhibitors of ethylene biosynthesis, aminoethoxyvinylglycine (AVG) and cobalt chloride (CoCl2), increased multiplication rate by providing a higher number of axes of a suitable size for subculture. The ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) had a beneficial effect on multiplication rate, although reducing longitudinal growth of the axes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00055514
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  • 8
    Electronic Resource
    Electronic Resource
    Somatic embryogenesis of Panax ginseng in liquid cultures: a role for polyamines and their metabolic pathways (2000)
    Springer
    Plant growth regulation 31 (2000), S. 209-214 
    Details
    ISSN: 1573-5087
    Keywords: Panax ginseng ; polyamines ; somatic embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A callus with embryogenic capacity was generated fromroot sections of Panax ginseng and used as aninoculum source for embryogenic liquid cultures in athree-step process: – a suspension culture of cellaggregates in the presence of an auxin/cytokininmixture, – an induction medium containing auxin only(for 5 to 30 days), – a regeneration medium containingcytokinin only (for one month). Up to 25 embryos wererecovered per 2.5 g of aggregates in these conditions.Incorporation of polyamines or their precursorsarginine and ornithine into either the induction orregeneration media increased the number of embryosproduced by up to 4 times. Inhibitors of bothbiosynthesis and biodegradation of polyamines reducedthe number of embryos. These results support earlierfindings of the role of polyamines in the process ofsomatic embryogenesis. The success of these liquidcultures opens up the possibility of producing somaticembryos of Panax ginseng in bioreactors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006344316683
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  • 9
    Electronic Resource
    Electronic Resource
    Disturbed sugar metabolism in a fully habituated nonorganogenic callus of Beta vulgaris (L.) (1993)
    Springer
    Plant growth regulation 13 (1993), S. 257-261 
    Details
    ISSN: 1573-5087
    Keywords: Beta vulgaris ; glycolysis ; hexose monophosphate pathway ; sugarbeet ; sugar metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Habituated (H) nonorganogenic sugarbeet callus was found to exhibit a disturbed sugar metabolism. In contrast to cells from normal (N) callus, H cells accumulate glucose and fructose and show an abnormal high fructose/glucose ratio. Moreover, H cells which have decreased wall components, display lower glycolytic enzyme activities (hexose phosphate isomerase and phosphofructokinase) which is compensated by higher activities of the enzymes of the hexose monophosphate pathway (glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase). The disturbed sugar metabolism of the H callus is discussed in relation to a deficiency in H2O2 detoxifying systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024846
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  • 10
    Electronic Resource
    Electronic Resource
    Low activity of amine-oxidases and accumulation of conjugated polyamines in disfavour of organogenic programs in Chrysanthemum leaf disc explants (1998)
    Springer
    Plant cell, tissue and organ culture 55 (1998), S. 85-94 
    Details
    ISSN: 1573-5044
    Keywords: budding ; callus ; polyamine anabolism ; polyamine catabolism ; rooting ; transglutaminase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Foliar discs (8 mm diameter) from expanding leaves of the middle part of vegetative shoots of Chrysanthemum morifolium Ramat raised in vitro were induced to form directly on specific media in vitro either roots or vegetative buds, or callus. The budding programme, on its specific medium, was deviated to callus formation by the addition of 2 mM β-OH-E (β-OH-ethyldrazine, an inhibitor of diamine oxidase). Conversely vegetative buds instead of callus were formed on the callus medium in the presence of 2 mM DFMO (difluoromethylornithine, an inhibitor of ornithine decarboxylase). Callus formation was characterized by high accumulation of free and particularly conjugated polyamines (PA), very low or undetectable activities of diamine- and polyamine oxidases, and transglutaminase. DFMO-deviation of callus initiation in favour of bud formation lowered the accumulation of PA and increased the activity of amine-oxidases. The high catabolism of PA in the organogenic (rooting, budding) programs was questioned as to its role in developmental processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006153806610
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