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PubMed2005

Assessment of the genotoxicity of 137Cs radiation using Vicia-micronucleus, Tradescantia-micronucleus and Tradescantia-stamen-hair mutation bioassays.

Since the middle of the 20th century, ionizing radiations from radioactive isotopes including 137Cs have been investigated to determine their genotoxic impact on living organisms. The present study was designed to compare the effectiveness of three plant bioassays to assess DNA damage induced by low doses of 137Cs: Vicia-micronucleus test (Vicia-MCN), Tradescantia-micronucleus test (Trad-MCN) and Tradescantia-stamen-hair mutation test (Trad-SH) were used. Vicia faba (broad bean) and Tradescantia clone 4430 (spiderwort) were exposed to 137Cs according to different scenarios: external and internal (contamination) irradiations. Experiments were conducted with various levels of radioactivity in solution or in soil, using solid or liquid 137Cs sources. The three bioassays showed different sensitivities to the treatments. Trad-MCN appeared to be the most sensitive test (significative response from 1.5 kBq/200 ml after 30 h of contamination). Moreover, at comparable doses, internal irradiations led to larger effects for the three bioassays. These bioassays are effective tests for assessing the genotoxic effects of radioactive 137Cs pollution.

Biological Assay↗
PubMed1999

Assessment of the genotoxicity of mine-dump material using the Tradescantia-stamen hair (Trad-SHM) and the Tradescantia-micronucleus (Trad-MCN) bioassays.

The Tradescantia-stamen hair (Trad-SHM) and -micronucleus (Trad-MCN) bioassays were used to determine the genotoxicity of two eluates derived from mine tailings. The goal was to test the suitability of the Tradescantia bioassays as screening tools for this kind of waste material. Leachates obtained using the current standard German leaching test methods (S4 eluate) as well as leachates obtained using a new eluation method (pHstat4) were tested and compared. Concentration of heavy metals in the pHstat4 eluate were much higher than in the S4 eluate. The chemical analysis corresponded well with the results of the bioassays. Exposure to solutions containing more than 1% pHstat4 eluate caused a significantly higher number of micronuclei. The Trad-SHM bioassay also showed an increased pink mutation rate when plants were exposed to 8 or 16% eluate solutions. In contrast, the S4 eluate only caused increased mutation rates when solutions containing more than 32% eluate were used. The low pH of the pHstat4 eluate was not responsible for the genotoxicity observed using both bioassays, as indicated by the lack of significant mutation rates in the nitric acid controls. This demonstrates that the Tradescantia bioassays can be used as tools to assess the genotoxic potential of environmental samples with a wide range of pH values, without the need for sample modification.

Biological Assay↗
PubMed2002

Pollen mother cells of Tradescantia clone 4430 and Tradescantia pallida var. purpurea are equally sensitive to the clastogenic effects of X-rays.

The Tradescantia micronucleus test is a sensitive bioassay for mutagenesis that may be employed both under field and laboratory conditions. This test has been standardized mostly on the basis of the results obtained with clone 4430. However, this clone is not well adapted to tropical weather, frequently showing problems with growth and flowering. In addition, it is attacked by parasites and insects, a fact that limits its use in field studies aiming at the biomonitoring of air pollution. In the city of São Paulo, Tradescantia pallida (Rose) Hunt. var. purpurea Boom is widely distributed as an ornamental plant in gardens and along roadsides and streets, mostly because of its natural resistance and its easy propagation. In this report, we present dose-response curves indicating that the sensitivity of T. pallida and clone 4430 to X-radiation (1, 10, 25 and 50 cGy) is similar. The results confirm our previous suggestion that T. pallida represents a good alternative for in situ mutagenesis testing in tropical regions, especially biomonitoring studies in which the exposure conditions may not be fully controllable.

Clone Cells↗
PubMedDate not supplied

Evaluation of genotoxic activity of maleic hydrazide, ethyl methane sulfonate, and N-nitroso diethylamine in Tradescantia.

OBJECTIVE: To assess the genotoxic activity of N-nitroso diethylamine (NDEA), maleic hydrazide (MH), and ethyl methane sulfonate (EMS) using two systems: the comet assay on nuclei from Tradescantia, and the pink mutation test on Tradescantia staminal hairs (clone 4430). MATERIAL AND METHODS: Tradescantia cups was obtained from Laboratorio de Citogenética y Mutagénesis del Centro de Ciencias de la Atmósfera de la Universidad Nacional Autónoma de México and treated with: N-nitroso diethylamine (NDEA) at 1, 5, 10 mM, maleic hydrazide (MH) at 1, 5, 10 mM and ethyl methane sulfonate (EMS) at 15, 30 and 45 mM; and used in both pink mutation assay and comet assay using cellular nuclei from Tradescantia staminal hairs. The observation of staminal hair was realized along eight days (6-14) after treatment), flowers produced day 14 after treatment were utilized done according to Underbrink. In previous reports on plants, were comet assay was used, breaking cellular wall and separating by centrifugation gradient are necessary. Here, nuclei from staminal hairs were obtained by squashing the cells (is not necessary to utilize to break special procedure cellular wall), collected using a nylon mesh of 80 Mm and next the comet assay was applied. Student's T test was the statistical test used for analyzing the comet assay data. RESULTS: Both assays showed a great sensitivity to the studied mutagens. A relationship between the dose-pink event and the dose-tail length was evident. Even though the Tradescantia mutation assay is a sensitive test with MH and EMS, low doses of NDEA were not able to induce a significant increase in the pink event frequencies; however, the comet assay was able to detect the mutagenic effect of NDEA at the same dose. Thus, it is clear that the comet assay is highly sensitive to the lowest dose of chemical mutagens. CONCLUSIONS: The comet assay on nuclei from Tradescantia staminal hairs is a useful tool to monitor genotoxic agents; it is simple, highly sensitive, and faster than the pink mutation test.

Comet Assay↗
PubMed2004

Toxicity to Tradescantia of technogenic radionuclides and their mixture with heavy metals.

The genotoxic effects on Tradescantia of (137)Cs, (90)Sr, and (236, 242)Pu, a heavy metal mixture [Cd, Cr(VI), Cu, Mn(II), Ni, Pb, Zn] and of a complex mixture of these toxicants were determined. The impact of radionuclides on plants subjected to ionizing radiation exposure was estimated. The number of somatic mutations and the quantity of nonviable stamen hairs were used as end points in the testing. An increase in the quantity of nonviable stamen hairs was observed with increasing internal exposure to (137)Cs, (90)Sr, and (236, 242)Pu; however, the number of somatic mutations was not observed to be dependent on ionizing radiation. The internal dose of individual radionuclides necessary to decrease the quantity of viable stamen hairs in Tradescantia by 50% can be arranged in the following sequence: (236, 242)Pu > (137)Cs > (90)Sr. Tradescantia died in the mixture of the radionuclides (90)Sr, (137)Cs, and (236)Pu (5 x 10(-2), 7 x 10(-5), and 4 x 10(-10) Gy, respectively) after 14 days, whereas the heavy metal mixture caused somatic mutations in 3% of the Tradescantia and nonviable stamen hairs in 7% but no mortality. However, the Tradescantia died in a combined mixture of these heavy metals and the radionuclides after 14 days. On the basis of all these observations, it can be concluded that the toxic effect of radionuclides was more significant than that of heavy metals.

Cesium Radioisotopes↗
PubMed2001

Response of Tradescantia albiflora to growth irradiance: Change versus changeability.

Most chloroplasts undergo changes in composition, function and structure in response to growth irradiance. However, Tradescantia albiflora, a facultative shade plant, is unable to modulate its light-harvesting components and has the same Chl a/Chl b ratios and number of functional PS II and PS I reaction centres on a Chl basis at all growth irradiances. With increasing growth irradiance, Tradescantia leaves have the same relative amount of chlorophyll-proteins of PS II and PS I, but increased xanthophyll cycle components and more zeaxanthin formation under high light. Despite high-light leaves having enhanced xanthophyll cycle content, all Tradescantia leaves acclimated to varying growth irradiances have similar non-photochemical quenching. These data strongly suggest that not all of the zeaxanthin formed under high light is necessarily non-covalently bound to major and minor light-harvesting proteins of both photosystems, but free zeaxanthin may be associated with LHC II and LHC I or located in the lipid bilayer. Under the unusual circumstances in light-acclimated Tradescantia where the numbers of functional PS II and PS I reaction centres and their antenna size are unaltered during growth under different irradiances, the extents of PS II photoinactivation by high irradiances are comparable. This is due to the extent of PS II photoinactivation being a light dosage effect that depends on the input (photon exposure, antenna size) and output (photosynthetic capacity, non-radiative dissipation) parameters, which in Tradescantia are not greatly varied by changes in growth irradiance.

Journal Article↗
PubMed2005

Characterization of a potyvirus isolated from Tradescantia fluminensis in northern Italy.

We isolated a potyvirus from Tradescantia fluminensis that was causing leaf distortion and mild mosaic. We cloned and sequenced a 1500 bp cDNA obtained by RT-PCR corresponding to the 3' proximal region of the genome. We determined the host range and tested a series of potyviral antisera against our tradescantia virus isolate by immuno-enzymatic methods. Based on our results, we suggest that our viral isolate could be considered a new potyvirus species named Tradescantia mild mosaic potyvirus. Phylogenetic analysis confirmed that Tradescantia mild mosaic virus belongs to the genus Potyvirus within the family Potyviridae, but the virus could not be assigned to any of the potyvirus groupings recently defined.

Amino Acid Sequence↗
PubMed1998

Evaluation of genotoxicity of emissions from municipal waste incinerators with Tradescantia-micronucleus bioassay (Trad-MCN).

A 4-year study was conducted to investigate the suitability of the Tradescantia-micronucleus bioassay (Trad-MCN) to detect genotoxicity of emissions from municipal waste incinerators. The genotoxic potential of emissions was assessed in three ways: (i) direct fumigation of Tradescantia with diluted incinerator emissions, (ii) exposure of Tradescantia to smoke condensates and (iii) in situ monitoring of genotoxicity of emissions near a municipal incinerator. The results of direct fumigation with smoke emissions varied over the course of the study. In 1992, significantly higher micronuclei frequencies (MCN) were always observed in treated plants than in control plants, regardless of length of fumigation period. Furthermore, MCN frequencies were significantly higher in plants fumigated for 24 h than those fumigated for 8 h, and MCN frequencies were also higher in plants fumigated in chamber 1 (low dilution, high stack gas concentration) than those in chamber 2 (P<0.05). MCN frequencies were substantially lower in 1993 and 1994, and in only 1 out of the 5 fumigation experiments were MCN frequencies significantly higher in treated plants than in controls. This drop in MCN frequencies was possibly due to the installation of better pollution control devices in the incinerator in 1993. Exposure to smoke condensates induced significant increases in MCN frequencies in most exposure trials. A drop in MCN frequencies over the course of the 4-year study was also attributed to the installation of new smoke scrubbing devices. This was further confirmed by the chemical analysis of the condensate, which showed a significant reduction in organic pollutants after the installation of the new devices. The results of in situ monitoring of genotoxicity near a municipal waste incinerator showed that MCN frequencies of Tradescantia depended on the distance from the incinerator, and the direction of wind. Because exposure periods of 6 h were insufficient to elicit significant responses, periods of 10 to 24 h are recommended for in situ monitoring.

Air Pollutants↗
PubMed2004

Evaluation of the mutagenic potential of urban air pollution in São Paulo, Southeastern Brazil, using the Tradescantia stamen-hair assay.

We used a short-term bioassay--the Tradescantia stamen-hair assay (TSH)--to evaluate the toxicity of ambient particles with an aerodynamic diameter less than 10 microm sampled in the metropolitan region of São Paulo, Brazil. Two exposure locations were selected: downtown São Paulo and Caucaia do Alto (mean PM10 levels of 64 and 14 microg/m3, respectively). The experiment was conducted July 11-August 15, 2002, and toxicity was assessed with the Tradescantia stamen-hair assay (TSH) employing clone KU-20 of Tradescantia. Four experimental groups were defined: inflorescences collected from plants cultivated in Caucaia, inflorescences collected from plants cultivated in São Paulo (to establish the baseline level of mutations in stamen hairs at both sites), inflorescences collected from plants cultivated in Caucaia and brought to São Paulo and maintained in chambers that received ambient air, and inflorescences collected from plants cultivated in Caucaia and brought to São Paulo and maintained in chambers that received air passed through a particle filter. The frequency of mutations observed in Caucaia was significantly lower than that in the remaining groups. Flower cuttings brought from Caucaia and receiving ambient air of São Paulo showed a rate of mutations similar to that of plants cultivated in São Paulo. Filtering particles from the air reduced the rate of mutation but not sufficiently to reach the level of that in Caucaia. The frequency of mutations observed in São Paulo was significantly associated with PM10 levels on the fifth day before the opening of the flowers (r = 0.47, p = 0.025). Our results indicate that urban particles play a significant role in the development of pollution-dependent mutations.

Air Movements↗
PubMed2006

In situ monitoring of clastogenicity of ambient air in Bratislava, Slovakia using the Tradescantia micronucleus assay and pollen abortion assays.

Aim of this study was to monitor the genotoxic effects of polluted air in Bratislava (Slovakia) with the Tradescantia micronucleus (Trad-MN) test. In situ monitoring was carried out at five locations during two seasons (years 2003 and 2004). Flower pots with Tradescantia paludosa (clone 03) plants were exposed for 6-8 weeks at the different sites each year. The highest MN levels were observed in the vicinity of an agrochemical factory (3.1 times higher than background level in 2003 and 2.7 times higher in 2004). Lower effects were seen when plants were exposed to urban traffic emissions or in the vicinity of a glass-producing plant (the MN frequencies ranged between 2.8 and 4.4 per 100 tetrads, respectively, while the control frequencies were 2.1-2.6 per 100 tetrads); exposure near a petrochemical plant had no significant effects. In pollen abortion assays, three wild growing species were used, namely, chicory (Cichorium intybus L.), old man's beard (Clematis vitalba L.) and common toadflax (Linaria vulgaris Mill.). Again, the strongest effects were observed close to the agrochemical industry (reduction of fertile pollen by 5.6%, 11.1% and 8.3% in chicory, old mans beard and in toadflax, respectively). Cichorium intybus was the most sensitive species and the number of abortive pollen grains was 5.1 times higher in specimens collected near the agrochemical factory than that seen at the control location. These observations indicate that contaminated urban air has an impact on the fertility of wild plants. Furthermore, it is interesting that the same rank order of effects was seen in pollen abortion assays as in the Trad-MN test (agrochemical industry>technical glass industry≥traffic>city incinerator/petrochemical plant). These results confirm the sensitivity of the Tradescantia MN test and pollen abortion assays for the detection of air pollution, and show that distinct differences exist in genotoxicity of different sources of pollutants.

Agrochemicals↗
PubMed1988

The plant activation of m-phenylenediamine by Tradescantia clone 03 and clone 4430 cells in liquid suspension culture.

In this study, we expanded the use of the genus Tradescantia to investigate the plant activation of promutagens and further refine the methodology of the plant cell/microbe coincubation assay. Liquid suspension cell cultures of Tradescantia clone 03 and Tradescantia clone 4430 were used to activate the promutagen m-phenylenediamine into a mutagenic compound which was detected by Salmonella typhimurium strain TA98 in the plant cell/microbe coincubation assay. Optimum treatment parameters were established for both plant cell lines. Optimum was defined as the lowest concentration or shortest time period that provided consistently positive results and high rates of revertants. Preliminary experiments with both cell lines defined 2.5 mumoles m-phenylenediamine per plate as the optimum concentration to be used in the determination of the optimal coincubation period and the optimal concentration of plant cells. These experiments also determined the optimal physiological stage at which both clones should be used in the coincubation assay. Differences were found in the optimal of coincubation (1h for clone 03, 2 h for clone 4430) and growth stage (mid-log for clone 03, mid- to late-log for clone 4430). Similar activation responses were seen for both clones when the concentration of plant cells (mg/ml) was varied. Under optimized conditions, clone 03 cells demonstrated an approximately 10% higher activation response than clone 4430.

Biotransformation↗
PubMed1992

The use of Tradescantia and Vicia faba bioassays for the in situ detection of mutagens in an aquatic environment.

Tests have shown plant bioassays to be excellent for mutagenicity studies. Most studies with plant bioassays, however, have been carried out either in the laboratory, or if, in situ, as monitors of atmospheric contaminants. The primary purpose of this study was to assess the utility of in situ plant mutagenicity bioassays in monitoring water contaminants. The assay systems tested were the Tradescantia stamen hair and micronucleus assays for the detection of gene mutations and chromosomal aberrations respectively, and the Vicia faba bioassay system which detects chromosomal aberrations in root tips. The assays were used to test the effluent from a pulp and paper mill located on the north shore of Lake Superior. Assays were performed in a creek containing raw effluent and in the bay of Lake Superior into which the creek emptied. All in situ treatments were carried out for 24 h. The effluent from the creek was heavy with pulp and debris which coated the plant cuttings and the Vicia faba seedlings and may have restricted the uptake from the effluent. In the creek, at test sites 11.5 km from the source, the effluent was toxic to the Vicia faba roots as evidenced by a reduction in the mitotic index. The data for the Tradescantia stamen hair assay in the creek were equivocal. The cuttings from the creek test sites and the air and water control sites appeared to have undergone a physiological delay. Within a day or two after the return to the laboratory, that is 6-8 days after testing, flowering almost ceased and did not fully resume until about day 35. This reduction in flowering was particularly severe with the cuttings from the effluent and air control sites, making it very difficult to interpret the results. In contrast, the Tradescantia micronucleus and Vicia faba chromosomal aberration data were unequivocal; each produced positive responses at both test sites relative to the air and water controls. The results obtained for the bay sites with all 3 assays were in agreement. In that section of the bay visibly contaminated by the creek effluent, increases in stamen hair mutants, micronuclei, and chromosome aberrations were measured. In general, there was a considerable reduction in the number of mutant events observed for the water samples brought back from the test sites and tested in the laboratory.(ABSTRACT TRUNCATED AT 400 WORDS)

Canada↗
PubMed1999

In situ monitoring of the ambient air around the chloroprene rubber industrial plant using the Tradescantia-stamen-hair mutation assay.

The city of Yerevan, the capital of Armenia, has been one of the heavily polluted cities since the earlier USSR era. A Chloroprene Rubber Industrial Plant has been the major contributor of air pollution in this city. The first attempt has been undertaken to detect the mutagenic effect of the ambient air around this industrial complex using the Tradescantia-stamen-hair-mutation (Trad-SHM) assay. Tradescantia clone 02 was used for this study. Pots of Tradescantia plants were exposed to ambient air in 10 different locations around the industrial establishment during the months of May and June, 1991 and 1992. Three series of in situ monitoring experiments were carried out. In the first series, sites numbers 1 through 4 were located in the industrial complex, and the second series, sites numbers 5 through 7 were located 1.0-1.3 km away from the Rubber Plant and the third series, sites numbers 8 though 10 were situated 1.5 km from the chemical plant and the monitoring plants were elevated at 5, 13, and 32 m above ground. A control group of plants were grown in a greenhouse about 13 km away from the polluted air from the chemical plant. Results of these two consecutive year's study show significantly elevated high levels of pink mutation events (PME) over the control at sites 1, 2, and 4 in the first series of the study. Positive responses were observed at all sites in the second series of the study. Only site 8 (June 1991) in the third series of the study was significantly higher in PME over the control.

Air Pollutants, Occupational↗
PubMed1999

The Tradescantia-micronucleus test on the genotoxicity of UV-B radiation.

Lanzhou city is located in north central China near inner Mongolia. The solar UV-B background radiation in this area is occasionally extremely high (8 microW/cm2). Such high background solar UV-B radiation could be attributed to the sporadic depletion of the ozone layer in the stratosphere. The excessive UV-B radiation is a potential hazard in the environment. This prompted the present study on the effect of UV-B radiation on the cytogenetic damage to pollen mother cells of the plant Tradescantia. The Tradescantia-micronucleus (Trad-MCN) test was used to determine the genotoxicity of UV-B radiation. In addition to the usual 10 h of solar emission of UV light a series of increasing dosages (2, 4, 6, 8 h) of artificial UV-B radiation was applied to Tradescantia (clone 3) plant cuttings. Inflorescences of the treated and control plants were fixed and used for preparation of microslides. Micronuclei frequencies were observed in the early tetrads to show the degree of genotoxicity. Results of two repeated experiments show a dose-related increase of MCN frequencies under normal sunshine days. In the third experiment conducted under a cloudy and rainy day and an extraordinary high solar UV-B background, the MCN frequencies were markedly higher than that of the negative control but did not show the clear dose response to the treatment as in the first two experiments. The Trad-MCN test has successfully detected the effect of artificial UV-B radiation over the solar UV-B background radiation.

China↗
PubMed1999

Tradescantia-micronucleus and -stamen hair mutation assays on genotoxicity of the gaseous and liquid forms of pesticides.

The clastogenic and mutagenic effects of the insecticide Dimethoate (Cygon-2E), herbicides Atrazine, Simazine (Princep), Dicamba (Banvel D) and Picloram (Tordon) were studied using the Tradescantia-micronucleus (Trad-MCN) and Tradescantia-stamen hair mutation (Trad-SHM) assays. In clone 4430, dimethoate fumes both significantly increased the pink mutation events and reduced the number of stamen hairs per filament with increasing dosages. The pink mutation events were elevated by the liquid treatment with Picloram at 100 ppm concentration. The result of Trad-MCN test on Dimethoate fumes was not significantly different between the control and treated groups. The herbicide Atrazine showed positive effects at 10-50 ppm dose (liquid) and signs of overdose at 100 and 500 ppm concentrations. Simazine was mildly positive in elevating the MCN frequencies in the dose range of 5 to 200 ppm (liquid doses). Both Dicamba and Picloram induced a dosage-related increase in MCN frequencies in the Trad-MCN tests using Tradescantia clone 03. However, in higher dosages (200 ppm or higher), there were signs of overdose, reduction of MCN frequencies and physical damage of the leaves and buds of plant cuttings.

Absorption↗
PubMed1999

Exploring the clastogenic effects of air pollutants in São Paulo (Brazil) using the Tradescantia micronuclei assay.

This study was designed to determine the clastogenicity of particulate matter (aerodynamic diameter smaller than 10 microm) in the urban polluted air in the city of São Paulo. The Tradescantia-micronucleus (Trad-MCN) assay was used throughout this study to evaluate the clastogenicity of the extracts of the particulate matter. Tradescantia pallida (Rose) Hunt. cv. purpurea, an indigenous cultivar, was used in the Trad-MCN assay. The efficacy of this plant material for the Trad-MCN assay was validated with dose-response studies using formaldehyde and beta radiation. Dose-response curves were established with these known mutagens. The extracts of the PM10 particles at concentrations between 5 and 50 ppm induced a dose-related increase in MCN frequencies. The results indicate that T. pallida is equally sensitive to mutagens as the standard Tradescantia clone 4430 or 03 and the particulate matter in the urban air are clastogenic to the chromosomes of this plant. Inhalation of these particles by urban dwellers may affect their health by inducing similar genetic damage.

Air Pollutants↗
PubMed2000

Auxin-dependent cell wall depositions in the epidermal periplasmic space of graviresponding nodes of Tradescantia fluminensis.

Differential growth of the nodal regions of graviresponding Tradescantia fluminensis (Wandering Jew) was analysed with special respect to the extension-restricting epidermal cells of the opposite growing and growth-inhibited organ flanks. Gravicurvature of horizontally gravistimulated isolated nodes depends on auxin (indolyl-3-acetic acid, IAA) and shows a node-specific profile in which the third node below the tip showed the greatest response. Exogenously supplied gibberellic acid induced no gravitropic growth. Vertically oriented isolated nodes supplied with exogenous IAA showed, on an electron microscopical level, conspicuous membrane invaginations with adjacent wall depositions restricted to the outer tangential epidermal cell walls. Their number was more than doubled by exogenously supplied Ca2+, which inhibited IAA-induced growth. No such changes could be detected in water-incubated segments or inner tissues of IAA-supplied segments. Gravistimulated differential growth of nodes of intact shoots and of nodal segments was characterized by changes similar to the ones induced by exogenous IAA, with greatly increased numbers of wall depositions within the epidermal cells of the growth-inhibited upper organ flank. Similar to the gravistimulated wall depositions, an asymmetric distribution pattern of Ca2+ was detected in the epidermal cell walls employing x-ray energy spectrum analysis (EDX). The results indicate that growth of nodes of Tradescantia fluminensis is regulated via IAA-induced secretion and subsequent infiltration of wall components enabling wall extension. The data support the hypothesis that temporary differential growth during gravicurvature of Tradescantia fluminensis is mediated by the antagonistic effect of Ca(2+)-ions on the infiltration of IAA-induced wall-loosening components into the outer, extension-restricting epidermal walls thereby inhibiting growth.

Calcium↗
PubMed2001

Karyotypes and Giemsa C-banding patterns of Zebrina pendula, Z. purpusii and Setcreasea purpurea, compared with those of Tradescantia ohiensis.

It has been proposed that the genera Zebrina and Setcreasea of the family Commelinaceae should be united and reunited, respectively, with the genus Tradescantia, mainly based on morphological studies. In the present study, karyotypes and Giemsa C-banding patterns in the root-tip cells of three Zebrina and two Setcreasea clones were analyzed, and were compared with those of a triploid Tradescantia clone. Z. pendula and Z. purpusii (both 2n = 24) were found to have similar karyotypes (4 M + 6 ST + 14 T; M = meta-, ST = subtelo-, T = telocentric chromosomes), while Z. pendula cv Quadricolor (2n = 23) had a unique karyotype (6 M + 5 ST + 11 T + 1 SA; SA = short acrocentric chromosome). The only clear difference between Z. pendula and Z. purpusii was that one and two subtelocentric chromosomes, respectively, had satellites at the short arms. Two clones of S. purpurea (2n = 24) had karyotypes (8 M + 8 M' + 8 SM; M' = nearly meta-, SM = submetacentric chromosomes) similar to each other. T. ohiensis (2n = 18) had a symmetric karyotype (9 M + 9 SM) consisting of larger chromosomes than S. purpurea. Many clear Giemsa C-bands were detected, in addition to centromeric bands in all chromosomes of all clones. Z. pendula and Z. purpusii commonly had single clear interstitial bands in eight telocentric chromosomes each, but they also had unique telomeric and other interstitial bands, respectively. Z. pendula cv Quadricolor had a unique banding pattern, i.e., satellite bands in the unique short chromosome, telomeric bands at the long arms of all metacentric chromosomes, and single interstitial bands in six telocentric chromosomes. Two clones of S. purpurea had telomeric bands at many chromosome arms and satellite bands in two nearly metacentric and one submetacentric chromosomes, but some differences were found between them. On the other hand, all the chromosomes of T. ohiensis had telomeric bands at both arms, and three submetacentric chromosomes had satellite bands. These result prove structural differentiation of chromosomes occurred among the clones, especially in Zebrina, and show that S. purpurea is relatively close to T. ohiensis, while Zebrina is obviously distant from the other two genera. Therefore, there remains a question cytologically at least for uniting Zebrina with Tradescantia.

Chromosome Banding↗