Telomere-binding proteins have recently been recognised not only as necessary building blocks of telomere structure, but namely as components which are of central importance to telomere metabolism being involved in regulation of telomere length as well as in protective (capping) function of telomeres. Although the knowledge on plant telomeric DNA-binding proteins lags behind that in human and yeast, recent data show both analogies and plant-specific features in the composition and interactions of telomeric proteins. This review focuses primarily on proteins with known amino acid sequence. These can be classified into following groups: 1) the family of proteins with Myb domain at C-terminus, 2) proteins with Myb domain at N-terminus, both binding double-stranded DNA of telomeric repeats TTTAGGG, 3) the single-stranded DNA-binding proteins, and 4) other proteins that act also in non-telomeric chromatin regions. Proteins with C-terminal Myb domain reported as IBP family were previously found in human, whereas Smh family representing proteins with Myb domain at N-terminus was identified only in plants. Also RRM family of the single-stranded DNA-binding proteins is likely to be plant specific.

In vitro organogenesis was achieved from callus derived from hypocotyl explants of Cucumis sativus L. cv. Poinsett 76. Calli were induced from hypocotyl explants excised from 7-d-old seedlings grown on Murashige and Skoog (MS) medium containing 87.64 µM sucrose, 0.8 % agar, 3.62 µM 2,4-dichlorophenoxy acetic acid and 2.22 µM 6-benzyladenine (BA). Regeneration of adventitious buds from callus (25 shoots explant^-1) was achieved on MS medium supplemented with 8.88 µM BA, 2.5 µM zeatin and 10 % coconut water after two subcultures in the same medium at 30-d interval. Gibberellic acid (1.75 µM) favoured shoot elongation and indole 3-butyric acid (7.36 µM) induced rooting. Rooted plants were hardened and successfully established in soil.

Ferredoxin-dependent glutamate synthase (Fd-Gogat; EC 1.4.7.1) in leaf and root plastids is the last enzyme involved in the pathway of nitrate assimilation in higher plants. Arabidopsis thaliana expresses two different genes: the first, light regulated, specific of green tissues and the second expressed in other tissues. In this work, we investigated whether in our clone, OsGog2 AC Y12595, this gene is up-regulated by light or it is expressed under darkness. Fd-Gogat specific activity, protein and mRNA increased after light treatment in rice shoots. In roots, the activity and the protein content remained constant, whereas the mRNA is repressed by light treatment. The results obtained using a specific probe, situated in the 3' untranslated region of the OsGog2 cDNA, indicated that OsGog2 gene is up-regulated by light and that its expression is tissue specific and suggested that a dark expressed Fd-Gogat gene could be present in rice similarly as in Arabidopsis.

In roots of Pisum sativum seedlings, the average lag-time required for initiation of the gravitropic response was reduced proportionally to the concentration of 24-epibrassinolide (EBL) added to the root solution (range of 10^-13 to 10^-8 M concentrations). A treatment with clotrimazole, a compound inhibiting steroid synthesis, prevents initiation of the gravitropic response. This effect was partly reverted by addition of EBL. From analysis of variability in the populations, it is suggested that BR conditions the root curvature through a gravitropic-induced change in sensitivity to the PGRs regulating cell elongation.

Susceptibility of Mexican cacti to Agrobacterium rhizogenes was evaluated in 65 species of 22 genera. Stem discs taken from in vitro cultured plants were inoculated with Agrobacterium rhizogenes A4 agropine-type strain that contains the wild RiA4 plasmid and the binary vector pESC4 with the nptII and gus genes. Hairy roots were produced directly from wounds, or starting from calli generated on the wounded surface, in 34 of the evaluated species. The frequency of hairy roots formation, the number of roots per explant and its growth rates were variable among the tested species. In the 31 remaining species the production of transformed roots was not observed under the conditions used in these experiments. Histochemical detection of β-glucuronidase (GUS) activity demonstrated the expression of this foreign gene in the hairy roots. PCR analyses demonstrated the presence of the rolB and nptII genes in the DNA of the transformed roots. The patterns of alkaloid-like compounds obtained by thin layer chromatography in some of the tested species were qualitatively similar between the transformed and non-transformed roots.

This experiment is designed to determine the most suitable conditions and media for propagating three selected fig (Ficus carica L.) clones through tissue culture. The clone 37 displayed a higher performance than clones 50 and 82. As the multiplication medium, the Murashige and Skoog (MS) medium containing 1 mg dm^-3 α-indole-3-butyric acid (IBA), 1 mg dm^-3 gibberellic acid and 5 mg dm^-3 6-benzyladenine were the best, whereas, MS medium complemented with 1.2 and 2.5 μM IBA or 1-naphthalene acetic acid (NAA) were better in respect to rooting. Peat followed by volcanic tuff gave the best performance for acclimatization to outdoor conditions.

A protocol is established for regeneration of the economically important cut flower plant, Gypsophila paniculata L., using shoot tips explants. Multiple shoots were obtained on Murashige and Skoog medium fortified with 0.5 mg dm^-3 each of α-naphthaleneacetic acid and 6-benzyladenine. Addition of 10 g dm^-3 agar promoted shoot proliferation and reduced the degree of shoot vitrification. Transfer to 3 mg dm^-3 indole^-3-butyric acid containing medium produced optimum root initiation and development. The produced plants as well as intact plants were subjected to the random amplified polymorphic DNA (RAPD) analysis. Using 9 primers, the total number of amplification products generated by polymerase chain reaction was 142 bands (15.7 bands per primer), of which 7.74 % showed polymorphism. The analysis of bands recorded, showed 92.25 % similarity. The results indicated that very low variation at the DNA level occurred during in vitro culture of Gypsophila.

The effect of short-term exposure to elevated CO₂ concentration and high irradiance on the activity of superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidases (GPX) and catalase (CAT), and on the extent of the lipid peroxidation was studied in bean (Phaseolus vulgaris L.) plants. Plants were exposed for 4 d (8 h a day) to irradiance of 100 (LI) or 1000 (HI) μmol m^-2 s^-1 at ambient (CA, 350 μmol mol^-1) or elevated (CE, 1300 μmol mol^-1) CO₂ concentration. Four-day exposure to CE increased the leaf dry mass in HI plants and RuBPC activity and chlorophyll content in LI plants. Total soluble protein content, leaf dry matter and RuBPC activity were higher in HI than in LI plants, although the HI and CE increased the contents of malonyldialdehyde and H₂O₂. Under CA, exposure to HI increased the activity of APX and decreased the total SOD activity. Under CE, HI treatment also activated APX and led to reduction of both, SOD and GPX, enzymes activities. CE considerably reduced the CAT activity at both irradiances, possibly due to suppressed rate of photorespiration under CE conditions.

Rice (Oryza sativa L.) was grown in pots with pyridine N-oxide (PNO), 4-morpholino pyridine N-oxide (MNO), and sodium meta silicate as the sources for silicon. Aliquots of these were added in fortnightly intervals to seedlings through anthesis stage. The plants were monitored for plant growth characteristics, chlorophyll content (SPAD values), photosystem 2 activity (variable to maximum fluorescence ratio of dark adapted leaves), and for blast and yellow stem borer resistance. Deposition of silica in the leaves was monitored by scanning electron microscopy and silicon mapping. PNO or MNO application resulted in significant silicon accumulation in leaf bundle sheath cells. Application of PNO and MNO imparted disease and pest resistance by increasing silicon uptake of rice plants.

The effects of sodium nitroprusside (SNP; nitric oxide donor) treatment on drought stress induced by PEG for different periods of time in wheat seedlings were investigated. Our results suggested that treatment for 2, 4 and 6 d with 15 % PEG could be termed as mild, moderate and severe stress, respectively. Drought stress induced accumulation of hydrogen peroxide and resulted in lipid peroxidation. On the other hand, activities of SOD, CAT and PAL increased under mild stress to counteract the oxidative injury and then decreased when the stress became severe (6 d). As the effect of SNP treatment, 0.2 mM enhanced wheat seedlings growth and kept high relative water content and alleviated the oxidative damage. However, 2 mM SNP aggravated the stress as a result of uncontrolled generation of reactive oxygen species and ineffectiveness of antioxidant systems.

A screening for the enzyme L-myo-inositol-1-phosphate synthase [EC 5.5.1.4] has been made first time in both vegetative and reproductive parts of the representative members of pteridophytes: Lycopodium, Selaginella, Equisetum, Polypodium, Dryopteris, and Gleichenia. The enzyme has been partially purified following low-speed centrifugation, streptomycin sulphate precipitation, ammonium sulphate fractionation, chromatography on DEAE-cellulose and gel-filtration through Sephadex G-200, and characterised from the reproductive pinnules of Gleichenia glauca Smith. The enzyme has a pH optimum at 7.5. The K_m for glucose-6-P and NAD⁺ were 0.922 × 10^-3 M and 0.9 × 10^-4 M, respectively. A basal activity of the enzyme has been recorded in absence of exogenous NAD⁺. The enzyme activity was augmented with NH₄Cl, but heavy metals like Hg²⁺, Cu²⁺ and Zn²⁺ inactivated it.

The relation between oxygen evolution rate (OER) and quantum yield of photochemical reactions in photosystem 2 (Φ_PS2) was examined in lichen symbiotic alga Trebouxia erici Ahmadjian (strain UTEX 911) exposed to different irradiances and osmotic stress (2 M sucrose for 60 h). Linear relationship was found between OER and Φ_PS2 in control cell suspension within irradiance range of 0 - 500 μmol m^-2 s^-1. Under osmotic stress, OER and Φ_PS2 were significantly reduced. Relation between OER and Φ_PS2 was curvilinear due to strong osmotically-induced inhibition of OER at high irradiance. The highest used irradiance (500 μmol m^-2 s^-1) was photoinhibitory for osmotically-stressed T. erici because non-photochemical quenching (NPQ) increased substantially. Energy-dependent quenching represented major part of NPQ increase. Osmotic stress led also to the reduction of capacity of photochemical processes in PS 2 (F_V/F_M) and increase in F₀/F_M. These changes indicated negative effects of osmoticum on structure and function of photosynthetic apparatus.

Glass microelectrodes were inserted into Dionaea muscipula (Venus flytrap) lobes and the action potentials (APs) were recorded in response to a sudden temperature drop or a direct current (DC) application. The effect of potassium channel inhibitor, tetraethylammonium ion, was the lengthening of the depolarization phase of AP. APs were also affected by the anion channel inhibitor, anthracene-9-carboxylic acid, that made them slower and smaller. Neomycin, which disturbs inositol triphosphate-dependent Ca²⁺ release, caused the visible inhibition of AP, too. Ruthenium red, which blocks cyclic ADP-ribose-dependent Ca²⁺ release, totally inhibited DC-triggered APs and induced the decrease in the amplitudes of cold-evoked APs. Lanthanum ions significantly inhibited both cold- and DC-induced membrane potential changes. It was concluded that during excitation Dionaea muscipula relied upon the calcium influxes from both the extra- and intracellular compartments.

The in vitro response of two Prunus rootstocks: GF 677 (Prunus persica × Prunus amygdalus), and Nemared (Prunus persica) to increasing concentrations of KCl of the culture medium was studied. Shoots were grown in vitro for 8 weeks on an Murashige and Skoog medium supplemented with 0, 5, 10, 15, 20, 40 or 80 mM KCl. By increasing KCl concentration from 0 to 40 mM, the number of shoots per explant was not significantly affected for both rootstocks. However, Nemared rootstock formed more shoots per explant than GF 677 under respective KCl concentrations of the medium. Inclusion of 80 mM KCl in the medium resulted in a reduction of growth of both rootstocks. Sodium, Fe, Mn, and Zn concentration in tissues of Nemared rootstock were significantly higher than the respective values of GF 677.

The present work was focused on abscisic acid (ABA) changes in three differently coloured petunias during flower development and senescence. The ABA content was studied in correlation with changes of flower pigments and other phytohormones. The variations of anthocyanins and endogenous hormones were induced by treatments with 1 or 2 mM amino-oxyacetic acid (AOA), 50, 100 μM thidiazuron (TDZ) and 50 μM 6-benzyladenine (BA). ABA content decreased during bud development and increased during senescence. The AOA reduced the anthocyanins content and avoided ABA increase, while the cytokinins (BA and TDZ) did not significantly affected anthocyanin contents but increased ABA content. TDZ doubled the ABA content compared to the control. However, the treatments did not affected flower life, confirming the secondary role of ABA during flower senescence.

In vitro regeneration of Trifolium glomeratum, a leguminous forage species, was attempted through leaf, petiole, cotyledon, hypocotyl, collar and root explants and two media combinations. Root and collar explants showed no callus induction. Medium with 0.05 mg dm^-3 α-naphthaleneacetic acid (NAA) and 0.10 mg dm^-3 N⁶-benzyladenine (BA) was more effective for hypocotyl explant whereas cotyledon and petiole explant were more responsive to 5.0 mg dm^-3 NAA and 1.0 mg dm^-3 BA. Friable, green calli obtained from petiole explant on this medium showed organogenetic potential. Modified root-inducing medium having 0.21 mg dm^-3 indole-3-acetic acid and 2.5 % sucrose was successful for root induction and plantlets were successfully transferred to field after hardening and Rhizobium inoculation.

A set of 104 wheat recombinant inbred lines (RILs) obtained from a cross between parents resistant (HD 29) and susceptible (WH 542) to karnal bunt (KB) (caused by Neovossia indica) were screened and used to identify random amplified polymorphic DNA (RAPD) markers linked with resistance to karnal bunt as these would allow indirect marker assisted selection of KB resistant genotypes. The two parents were analysed with 92 RAPD primers. A total of 65 primers proved functional by giving scorable polymerase chain reaction (PCR) products. Of these, 21 (32 %) primers detected polymorphism between the two parental genotypes. Using these primers, bulked segregant analysis was carried out on two bulk DNAs, one obtained by pooling DNA from 10 KB resistant RILs and the other similarly derived by pooling 10 KB susceptible RILs. One marker, OPM-20 showed apparent association with resistance to KB. This was confirmed following selective genotyping of individual RILs included in the bulks.

Seasonal dynamic of total nonstructural saccharides (TNS) and individual saccharides (starch, sucrose, glucose, fructose, fructans) was followed in rhizomes and stem bases of Calamagrostis epigeios (L.) Roth at two types of meadows communities in the South Moravia (Czech Republic): cnidion and molinion alliances, which differ in their water regime. The TNS were formed mainly by fructans and starch, while glucose, sucrose and fructose were low. The amount of TNS in rhizomes and stem bases of plants from wet cnidion site was higher than in plants from drier molinion site. The seasonal trends of all saccharides were similar in the both sites. During growing season (June to October) the main storage sugar was fructan (18 - 21 % of dry biomass). At the beginning of September the content of fructan decreased to 10 - 12 % and simultaneously the content of sucrose increased from 1 to 3 %. This may increase frost resistance. The content of TNS in the stem bases was lower than in the rhizomes. During winter time the stem bases contained 2 to 2.5 % of sucrose. Plant height and aboveground biomass were also higher in molinion site.

We have designed and constructed four oligonucleotides corresponding to the most conserved regions of ornithine decarboxylases (ODC; EC 4.1.1.17) of plant origin. These oligonucleotides were used for the amplification of homologous fragments from several plants (Zea mays, Capsicum annuum, Sorghum bicolor, Phaseolus vulgaris, Carica papaya and Daucus carota). The amplified fragments were cloned and sequenced, revealing high homology to other ODCs. Peptide sequences coded by these fragments were compared by Clustal analyses. These analyses identified the location of the conserved sequences corresponding to the binding sites of substrate and cofactor. Data demonstrated that the plant ODCs fragments lacked intron sequences and were extremely homologous (over 80 %), constituting a compact group separated from other eukaryotic ODCs.

Programmed cell death (PCD) was triggered in wheat leaves by a heat treatment (42 °C). This treatment caused DNA fragmentation as shown in DNA laddering analysis and in terminal deoxynucleotidyl transferase-mediated deoxyuridine-5'-triphosphate (dUTP) nick end labeling (TUNEL) analysis. Methanol and acetone treatment of leaves significantly blocked PCD. Western analysis indicated that a 65 kDa poly(ADP-ribose) polymerase-like protein was degraded during the treatment. However, high temperature (80 °C) treatment caused necrosis but not PCD.

We selected a informative set of twelve amplified fragment length polymorphism (AFLP) primer pairs suitable for evaluation of Chinese chestnut (Castanea mollissima Blume) genotypes. Cluster analysis based on 198 polymorphic AFLP amplified by these 12 primer pairs clearly divided investigated genotypes according to their place of origin. We showed, that genetic basis of modern genotypes is narrow also in the case of this species.

Changes of morphogenic competence in mature P. sylvestris L. buds due to frozen storage were investigated. The highest callus formation was registered on explants stored at -18°C for three months, but on explants stored for five months, it was also higher than in the control. Budding and development of needles in vitro was observed only for buds frozen three to five months. Peroxidase activity was lowest in these buds. In contrast, polyphenol oxidase activity in bud tissues continually increased during frozen storage. Within 10 months of frozen storage the content of starch and sugars in resting buds changed. It may be concluded that changes in composition of non-structural sugars in pine buds after five months of frozen storage are part of metabolic changes leading to loss of morphogenic capacity.

Genome size has been estimated by flow cytometry in 14 populations belonging to eight taxa (seven species, one of them with two varieties) of the genus Tripleurospermum. 2C nuclear DNA amounts range from 4.87 to 9.22 pg, and nuclear DNA amounts per basic chromosome set from 1.99 to 2.75 pg. Statistically significant differences depending on ploidy level, life cycle or environmental factors such as altitude have been found. Also, genome size is positively correlated with total karyotype length. The presence of rhizome is related to nuclear DNA content in these species.

Although it is well accepted that cytokinins (CKs) regulate processes such as leaf senescence and stomatal conductance, data on CKs in the canopy of mature trees are lacking in the literature. Here we report the first in situ sampling for determination of CKs in mature sugar maple (Acer saccharum) canopy layers. The upper canopy showed a distinct seasonal pattern in total CK content, while the lower canopy remained relatively unchanged.

A simple and efficient protocol for high frequency plant regeneration of a grain legume grasspea (Lathyrus sativus L.) is described. Of different explant types tested epicotyl segments were most responsive. Murashige and Skoog's (1962) medium augmented with 17.76 µM 6-benzyladenine + 10.74 µM α-naphthaleneacetic acid showed the highest percentage of direct shoot regeneration. Among cultivars IC-120487 showed the highest regeneration frequency (80 %) with maximum shoot numbers (8.2 shoots per explant) and maximum average shoot length (4.1 cm). About 78 % of the regenerated shoots were rooted in half-strength MS medium containing 2.85 µM indole-3-acetic acid. After primary hardening the plantlets were established in soil with a survival rate of 75 %.

Embryogenic suspension cultures of soybean (Glycine max L. cv. Iroquois) were subjected to mutagenesis using varying concentrations (1, 3, 10, and 30 mM) of ethyl methanesulfonate (EMS). Depending on the concentration of EMS used, the mean survival rate of embryogenic cultures decreased from 74 % (1 mM EMS) to 43 % after 30 mM EMS treatment. Random amplified polymorphic DNA (RAPD) analysis was used to determine whether induction of genetic variability in embryogenic cultures in response to the different EMS treatments may result in identification of polymorphic markers. Two of 35 'core' primers tested revealed polymorphisms. One of the primers, OPO-01/1150, revealed polymorphism in tissue treated with 10 mM EMS, while the other primer, OPO-05/1200, revealed polymorphism in tissue treated with either 1 or 30 mM EMS. These results suggest that RAPD markers are useful in detecting mutations in embryogenic cultures of soybean.

Treatment with methyl jasmonate (MeJA) stimulates a multicomponent defense response in leaves and suspension-cultured cells of grapevine (Vitis vinifera L. cv. Limberger). MeJA induces development of necrotic lesions, similar to that normally associated with resistance to avirulent pathogens. Sustained exposure of both leaves and cell-suspension cultures to 50 μM MeJA provoked hypersensitive cell death, stimulated medium alkalinization accompanied by massive callose deposition, but did not induce accumulation of hydrogen peroxide from the oxidative burst. Transcripts of genes encoding diverse families of the pathogenesis-related proteins accumulated rapidly after MeJA application, followed by salicylic acid production. After several days systemic accumulation of a large number of defense-associated proteins, including pathogenesis-related proteins, peroxidase, cell wall extensin and enzymes involved in the phenylpropanoid biosynthetic pathway was induced. These cumulative results suggest that grapevine cells that perceived MeJA generated a cascade of events acting at both local and long distances, and causing the sequential and coordinated expression of specific defense responses with a timing and magnitude similar to the typical hypersensitive response against pathogens.