The role of the actin cytoskeleton in somatic embryo development was investigated using latruncul... more The role of the actin cytoskeleton in somatic embryo development was investigated using latrunculin B and cytochalasin D. Brief treatments (1h) with either drug at the start of maturation fragmented the actin in suspensor cells and/or depolymerized actin filaments in meristematic cells. The drugs targeted different cells: latB primarily affected the suspensor cells, but cchD damaged both suspensor and meristematic cells. Lethal damage to the meristematic and suspensor cells was observed when the drugs were applied throughout the maturation period, although the severity of this effect depended on their concentrations. The drugs' effects on the yield of mature somatic embryos were investigated by applying them to embryo cultures throughout the maturation period or for one week at three different points in the maturation process: immediately prior to the start of maturation, during the first week of maturation, and during the fourth week of maturation. The strongest effects were observed when the drugs were applied at the start of maturation. Under these conditions, latB destroyed the suspensors, eliminating the underdeveloped embryos that depend on them. This accelerated the development of embryos that were capable of separating from the suspensors. Thus, while the total number of embryos at the end of the maturation period was lower than in untreated control cultures, the surviving mature embryos were of high quality. cchD treatment at the start of maturation strongly inhibited embryo development. Drug treatment at the end of the maturation period did not significantly affect embryo development: latB caused no change in the yield of somatic embryos, but cchD treatment increased the number of malformed embryos compared to untreated controls.
Liquid Culture Systems for in vitro Plant Propagation, 2005
Embryogenic cultures of Norway spruce (Picea abies) were cultivated either on solidified media, i... more Embryogenic cultures of Norway spruce (Picea abies) were cultivated either on solidified media, in liquid media, or on polypropylene membrane rafts (LifeRaft). The cultivation on rafts was found to be the most successful way: the number of developed somatic embryos increased, synchronization of the development was enhanced, and the time necessary for embryo development and maturation was shortened. It was
During ageing of bean (Phaseolus vulgaris L.) cotyledons in plants with modified life span the ti... more During ageing of bean (Phaseolus vulgaris L.) cotyledons in plants with modified life span the time-course of four cytokinins, ethylene, and the end products of free radical attack, lipofuscin-like pigments (LFP), were studied. UV irradiation shortened cotyledon life span, while epicotyl decapitation prolonged it. In controls, LFP increased at the senescence onset but at the end of life span it
A soil-plant transfer study was performed using soil from a former uranium ore processing factory... more A soil-plant transfer study was performed using soil from a former uranium ore processing factory in South Bohemia. We present the results from greenhouse experiments which include estimates of the time required for phytoremediation. The accumulation of (226)Ra by different plant species from a mixture of garden soil and contaminated substrate was extremely variable, ranging from 0.03 to 2.20 Bq (226)Ra/g DW. We found differences in accumulation of (226)Ra between plants from the same genus and between cultivars of the same plant species. The results of (226)Ra accumulation showed a linear relation between concentration of (226)Ra in plants and concentration of (226)Ra in soil mixtures. On the basis of these results we estimated the time required for phytoremediation, but this appears to be too long for practical purposes.
Plant enzymes participating in degradation of nitroaromatic compounds have not been biochemically... more Plant enzymes participating in degradation of nitroaromatic compounds have not been biochemically characterized in details so far. From suspension culture of soapwort (Saponaria officinalis L.) we isolated a novel plant oxidoreductase involved in degradation of trinitrotoluene (TNT). The enzyme catalyses first steps of reduction of TNT nitro groups in the presence of NAD(P)H under anaerobic conditions. The enzyme is monomeric with molecular mass 29 kDa, its two isoforms have pI 4.8 and 5.1. According to the spectral and activation analysis the enzyme contains flavinmono-nucleotide as a prosthetic group. The structure properties suggest an evolutional relationship to oxophytodienoate reductase. The N-terminal amino acid sequence shows homology to family of Old Yellow Enzyme (E.C. 1.6.99.1).
The role of the actin cytoskeleton in somatic embryo development was investigated using latruncul... more The role of the actin cytoskeleton in somatic embryo development was investigated using latrunculin B and cytochalasin D. Brief treatments (1h) with either drug at the start of maturation fragmented the actin in suspensor cells and/or depolymerized actin filaments in meristematic cells. The drugs targeted different cells: latB primarily affected the suspensor cells, but cchD damaged both suspensor and meristematic cells. Lethal damage to the meristematic and suspensor cells was observed when the drugs were applied throughout the maturation period, although the severity of this effect depended on their concentrations. The drugs' effects on the yield of mature somatic embryos were investigated by applying them to embryo cultures throughout the maturation period or for one week at three different points in the maturation process: immediately prior to the start of maturation, during the first week of maturation, and during the fourth week of maturation. The strongest effects were observed when the drugs were applied at the start of maturation. Under these conditions, latB destroyed the suspensors, eliminating the underdeveloped embryos that depend on them. This accelerated the development of embryos that were capable of separating from the suspensors. Thus, while the total number of embryos at the end of the maturation period was lower than in untreated control cultures, the surviving mature embryos were of high quality. cchD treatment at the start of maturation strongly inhibited embryo development. Drug treatment at the end of the maturation period did not significantly affect embryo development: latB caused no change in the yield of somatic embryos, but cchD treatment increased the number of malformed embryos compared to untreated controls.
Liquid Culture Systems for in vitro Plant Propagation, 2005
Embryogenic cultures of Norway spruce (Picea abies) were cultivated either on solidified media, i... more Embryogenic cultures of Norway spruce (Picea abies) were cultivated either on solidified media, in liquid media, or on polypropylene membrane rafts (LifeRaft). The cultivation on rafts was found to be the most successful way: the number of developed somatic embryos increased, synchronization of the development was enhanced, and the time necessary for embryo development and maturation was shortened. It was
During ageing of bean (Phaseolus vulgaris L.) cotyledons in plants with modified life span the ti... more During ageing of bean (Phaseolus vulgaris L.) cotyledons in plants with modified life span the time-course of four cytokinins, ethylene, and the end products of free radical attack, lipofuscin-like pigments (LFP), were studied. UV irradiation shortened cotyledon life span, while epicotyl decapitation prolonged it. In controls, LFP increased at the senescence onset but at the end of life span it
A soil-plant transfer study was performed using soil from a former uranium ore processing factory... more A soil-plant transfer study was performed using soil from a former uranium ore processing factory in South Bohemia. We present the results from greenhouse experiments which include estimates of the time required for phytoremediation. The accumulation of (226)Ra by different plant species from a mixture of garden soil and contaminated substrate was extremely variable, ranging from 0.03 to 2.20 Bq (226)Ra/g DW. We found differences in accumulation of (226)Ra between plants from the same genus and between cultivars of the same plant species. The results of (226)Ra accumulation showed a linear relation between concentration of (226)Ra in plants and concentration of (226)Ra in soil mixtures. On the basis of these results we estimated the time required for phytoremediation, but this appears to be too long for practical purposes.
Plant enzymes participating in degradation of nitroaromatic compounds have not been biochemically... more Plant enzymes participating in degradation of nitroaromatic compounds have not been biochemically characterized in details so far. From suspension culture of soapwort (Saponaria officinalis L.) we isolated a novel plant oxidoreductase involved in degradation of trinitrotoluene (TNT). The enzyme catalyses first steps of reduction of TNT nitro groups in the presence of NAD(P)H under anaerobic conditions. The enzyme is monomeric with molecular mass 29 kDa, its two isoforms have pI 4.8 and 5.1. According to the spectral and activation analysis the enzyme contains flavinmono-nucleotide as a prosthetic group. The structure properties suggest an evolutional relationship to oxophytodienoate reductase. The N-terminal amino acid sequence shows homology to family of Old Yellow Enzyme (E.C. 1.6.99.1).
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Papers by Martin Vágner