Callogenesis, somatic embryogenesis and regeneration capacity in twenty-three agronomically important spring barley (Hordeum vulgare L.) cultivars on induction media with 2,4-dichlorophenoxyacetic acid (2,4-D) or 3,6-dichloro-o-anisic acid (dicamba) and on modified regeneration media were studied. The frequency of zygotic embryos exhibiting callogenesis varied from 88 to 100 % according to genotype. Dicamba was more suitable for somatic embryogenesis induction and exhibited a higher frequency of regenerants than did 2,4-D. Green regenerants were obtained in all cultivars, and there were no albino plants. Except for cv. Victor all cultivars used in the experiment showed lower regeneration capacity as compared to the model cv. Golden Promise.

Effect of phosphorus deficiency on photosynthetic and respiratory CO₂ exchanges were analysed in primary leaves of 2-week-old bean (Phaseolus vulgaris L. cv. Golden Saxa) plants under non-photorespiratory (2 % O₂) and photorespiratory (21 % O₂) conditions. Low P decreased maximum net photosynthetic rate (P_Nmax) and increased the time necessary to reach it. In the leaves of P-deficient plants the relative decrease of P_Nmax at 2 % O₂ was larger than at 21 % O₂. The results suggested the influence of photorespiration in the cellular turnover of phosphates.

Shoot formation from seedling explants of Pinus heldreichii was induced by pulse treatment with benzyladenine at different concentration, followed by culture on medium lacking plant growth regulators. After treatment with 222 μM benzyladenine (BA) an average of 4.6 shoots per explant was obtained. Shoots, detached from explants, rooted with a frequency of about 10 %, and rooted plantlets were successfully transferred to ex vitro conditions.

Ponderosa pine (Pinus ponderosa Dougl. ex Laws.) seedlings were exposed to near ambient or elevated CO₂ (average concentrations during the last growing season 446 versus 699 μmol mol^-1), combined with low or elevated O₃ for three seasons. Ozone exposure during the last growing season (accumulated dose above threshold 0.06 μmol mol^-1) was 0.05 versus 26.13 μmol mol^-1 h. Needles of the youngest age class were harvested after the dormancy period. Ozone exposure decreased needle contents of chlorophyll a, chlorophyll b, and ascorbate, and resulted in a more oxidized total ascorbate and a more de-epoxidized xanthophyll cycle pool irrespective of the CO₂ level. Trees under elevated CO₂ had a more oxidized glutathione pool and lower chlorophyll a content. Contents of glutathione, tocopherol, and carotenoids were not affected by the CO₂ or O₃ treatments. There were no interactive effects between elevated CO₂ and elevated O₃ on any of the parameters measured. The results suggest that elevated atmospheric CO₂ concentration does not compensate for ozone stress by increasing antioxidative capacity in ponderosa pine.

Morphological, physiological, fruit yield and quality related traits were compared between the seed-grown and tissue-cultured plants of tomato (Lycopersicon esculentum Mill.) cv. Red Coat in a greenhouse. No significant differences were observed for any of the traits studied except for the number of leaves and branches, which were higher in the seed-grown plants than in tissue-cultured plants at the later stages of growth. No phenotypic abnormality of the tissue-cultured plants was observed suggesting that genetic fidelity of tissue cultured plants can be maintained if appropriate plant growth regulators are used with fewer member of subcultures in the multiplication medium.

Embryogenic, friable and small (ca. 3 mm) calli showed optimum gus expression and were best suited for selection during genetic transformation of rice through particle bombardment. Through prolonged culture of mature seeds on original callus induction medium, this type of calli could be produced in large numbers across several elite rice genotypes. To minimize the non-transformed escapes 50 mg dm^-3 hygromycin and 8 mg dm^-3 glufosinate ammonium were found to be critical during selection. Addition of selection marker during regeneration was essential. Regular and frequent (every 15 d) transfer of calli to fresh selection medium for three cycles was also important. A simple and economic procedure for screening large number of putative resistant plants was described.

The effects of equilibration under different air relative humidities (RH, 1 - 90 %) and temperatures (35 and 45 °C) on soybean (Glycine max) and wheat (Triticum aestivum) seeds were studied using different techniques. Seed moisture content, electrical conductivity (EC) of seed leachate and per cent seed germination were measured following standard procedures, and compared with nuclear magnetic resonance spin-spin relaxation time (T₂) measurements. Moisture contents of soybean and wheat seeds, following the reverse sigmoidal trend, were greater at 35 than at 45 °C at any particular RH. Changes in T₂ were related to the changes in germination percentage and leachate EC of both soybean and wheat seeds. Equilibrating soybean seeds at RH ≤ 11 % decreased germination percentage with corresponding decrease in T₂. On the contrary, EC of seed leachate increased. In wheat seeds equilibrated at 45 °C, T² was maximal at RH 5.5 %. T₂ declined in seeds equilibrated at high RH (> 80 %) together with low germination percentage.

For expression of MRJP1 - the most abundant protein of honeybee royal jelly - in plants, plasmid carrying the expression cassette composed of CaMV 35S RNA promoter, cDNA encoding MRJP1 with its native signal peptide, and nos3' as transcription terminator in binary vector pBin19 was prepared. The plasmid was introduced into tobacco (Nicotiana tabacum L. cv. Wi38) plants by Agrobacterium tumefaciens-mediated transformation. Transgenic F₁ and F₂ generation was grown from the seeds of the primary obtained transgenic tobacco plants. Immunoblot analyses of protein leaf extracts from transgenic plants showed expression of MRJP1.

Buckwheat (Fagopyrum esculentum Moench) is a heterostylous plant displaying heteromorphic sporophytic self-incompatibility (SI). In order to detect proteins involved in SI, pistils from both long and short styles were isolated and then selfed or cross-pollinated. One-dimensional gel electrophoresis revealed that short pistils 2 h after selfing contained an unique 50 kDa protein. In the two-dimensional electrophoresis two distinct groups of proteins possibly involved in SI response were detected in the short, and one in the long pistils.

In the present paper a Random Amplified Polymorphic DNA (RAPD) investigation was carried out on DNAs from five Crocus sativus L. (saffron) accessions cultivated in different countries and on six closely related Crocus species. Aims of the study are to check whether cultivated saffron has maintained a constant genomic organisation and to clarify its relationships with possible ancestor species. For the fifteen primers, which produced positive results, DNAs of saffron corms from different accessions present the same amplification pattern, in accordance with the similar DNA content and base composition pointed out in previous studies. The amplification of the seven Crocus species DNAs with twenty-one primers provided 217 repeatable and interpretable fragments, which were scored for presence/absence and employed for a cluster analysis. Results indicated that C. sativus is very closely related to C. cartwrightianus and also similar to C. thomasii. This result, concurring with part of the previous evidence, would rule out the hypothesis of close relationships between C. sativus and C. pallasii.

Twenty genotypes of Stylosanthes consisting four species were evaluated under rain fed condition employing biochemical and physiological attributes to select drought tolerant lines. Relative water content measured at 50 % flowering stage of the plants showed significant variations among the lines which ranged from 32.11 in S. scabra RRR94-86 to 83.33 % in S. seabrana 2539. The results indicated that S. scabra genotypes were more tolerant to drought over other lines as evidenced by high leaf thickness, proline accumulation, content of sugars and chlorophyll, and nitrate reductase activity.

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 returned to the initial level. Ethylene increased more than 3-fold at the time of abscission. The content of individual cytokinins (zeatin, zeatin riboside, isopentenyl adenine, isopentenyl adenine riboside) varied differently during ageing but they did not decreased in any case under level observed in young cotyledons at the time of abscission. UV irradiation resulted in 14-fold increase in LFP concentration at the end. Ethylene increased 8-fold 2 h after irradiation. Individual cytokinins increased after UV irradiation to a different extent and time-course, nevertheless cotyledon life span was shortened. Decapitation induced LFP decrease. On day 13, LFP abruptly increased and than decreased and stayed lowered until abscission. Ethylene was maximum on day 24, at the time of abscission, it was above 200 % of control. Decapitation produced transient decrease in some cytokinins namely zeatin and isopentenyl adenine riboside.

The effect of Cd (10, 100, and 200 μM) on tissue contents of macronutrients (N, P, K, Ca, Mg) and micronutrients (Fe, Zn, Cu, Mn) was investigated in hydroponically grown soybean (Glycine max) seedlings. Concentration changes of analysed elements observed against increasing Cd accumulation indicated that acute Cd-phytotoxic effect monitored through chlorophyll content was not a consequence of nutrient deficiency.

The effect of different hermetic and non-hermetic closure-types (aluminum foil, cotton bung, cotton plug, polypropylene cap and Steristopper) on potato (Solanum tuberosum L.) plantlets growth and chlorophyll contents was studied in three genotypes belonging to different maturity groups. Plantlets grown in culture tubes closed with aluminum foils and polypropylene caps had higher fresh mass and shoot length, but lower chlorophyll contents, higher senescence index and various morphological abnormalities. Non-hermetic closures like cotton plugs and Steristoppers were found optimum for plant growth without any morphological abnormalities. Besides, these plantlets exhibited low senescence index and had higher chlorophyll contents that favour acclimation to ex vitro conditions.

Suckers collected from different populations of Musa acuminata ssp. malaccensis were found to be highly resistant to race 4 of Fusarium oxysporum f. sp. cubense (FOC) suggesting that local wild banana populations co-evolved with the pathogen. Seedlings from these wild banana plants segregated for resistance to the pathogen. The infected seedlings were characterized based on external and internal symptoms and the variable response to FOC was mainly due to the genetic factors. Using the technique of random amplified polymorphic DNA (RAPD), 96 major amplification products from 15 primers were identified. Only 10 out of 96 markers were monomorphic and shared among the seed progenies, whereas the remaining 86 were highly polymorphic. Three primers showed banding patterns specific to resistant or susceptible seedlings. These results showed the great potential of the wild Musa acuminata ssp. malaccensis as a source for banana improvement and also for the synthesis of segregating populations for linkage mapping, gene cloning and DNA markers related to FOC resistance.

Ascorbic acid oxidase (AAO) has been fully characterized at molecular level, yet its functional role is unclear. The properties of the enzyme and the main hypotheses on its function are discussed. Recent data and reappraisal of previous observations suggest that AAO could be part of a dynamic mechanism operating whenever plant cells have to control oxygen availability.

Lemna minor L. roots were treated with different concentrations of NaCl. Lipid peroxidation was investigated histochemically and biochemically. At higher NaCl concentrations an increase in staining was observed in the root apices as compared to control for lipid peroxidation and loss of membrane integrity as well as an increase in contents of thiobarbituric acid reactive substance and peroxide. Both the non-enzymic antioxidants, ascorbate and glutathione increased with the NaCl concentration in the roots. Whereas an increase in superoxide dismutase, guaiacol peroxidase, and glutathione reductase activities were marked, catalase activity decreased in the roots under NaCl stress.

A full length cDNA (designated CrETR1) was isolated by polymerase chain reaction amplification of a cDNA library from periwinkle (Catharanthus roseus) cell cultures. CrETR1 cDNA encodes a polypeptide of 740 amino acids with a predicted molecular mass of 82 kDa. The deduced protein contains a hydrophobic ethylene-binding transmembrane region, a GAF domain, a third domain homologous to the histidine protein kinase domain of the prokaryotic two-component systems, and a fourth carboxyl-terminal domain homologous to the receiver domain of the response regulators, as found in the A. thaliana ethylene receptor ETR1. CrETR1 transcripts are strongly accumulated in petals and ovaries of C. roseus young plants whereas no significant changes are detected in cell cultures submitted to various stress or hormonal (including ethylene) treatments. The amount of the monoterpene indole alkaloid ajmalicine in the cells treated by ethylene is reduced after addition of inhibitors of histidine kinases showing a possible involvement of CrETR1 protein in the ethylene-related signalling pathway leading to alkaloid biosynthesis enhancement in C. roseus cell cultures.

Resistance to herbicide Basta® was introduced into pure inbred lines of Savoy cabbage (Brassica oleracea L. var. sabauda) by cocultivation of cotyledon and hypocotyl explants with Agrobacterium tumefaciens strains AGL1/pDM805 and LBA4404/pGKB5 (LB5-1). Shoot regeneration occurred on Murashige and Skoog medium supplemented with 1 mg dm^-3 6-benzyladenine and 0.5 mg dm^-3 indole-3-butyric acid at 42.3 % and 71.4 % of hypocotyl explants treated with AGL1/pDM805 and LB5-1, respectively. Putative transformants that survived selection on 10 mg dm^-3 phosphinothricin (L-PPT) supplemented medium were confirmed by GUS assay and PCR analysis. The transformation rate was 58 % with AGL1/ pDM805 and 25 % with LB5-1. Rooted plantlets were acclimated and then again screened for Basta®-resistance by spraying with 15 - 60 mg dm^-3 L-PPT. Surviving plants were selfed and Basta®-resistance was demonstrated in T₁ progeny.

Tobacco (Nicotiana tabacum L. cv. BY-2) cell lines tolerant to 700 μM Ni in which unselected cells can not grow, were selected. The Ni-tolerant cells were also more tolerant to Co, but not to Cd than unselected cells. Ni concentrations in Ni-tolerant cells were always higher than those in medium. Since buthionine sulfoximine did not affect their Ni-tolerance, it is suggested that phytochelatins are not involved in Ni-tolerance of Ni-tolerant cells. On the other hand, histidine contents in Ni-tolerant and unselected cells, which were treated with Ni, were higher that those treated without Ni, and the degree of the elevation of histidine contents by Ni-treatment was higher in Ni-tolerant cells than in unselected cells. Additionally, exogenous histidine reduced the inhibitory effect of Ni on the growth of unselected cells. In addition, the cells that were tolerant to histidine-analogue, had higher contents of histidine and Ni-tolerance. These results suggest that histidine is involved in Ni-tolerance and the detoxification of Ni in symplast in Ni-tolerant cells.

Two small cationic peptide fractions (5 kDa) were isolated from dry and germinated seeds of wheat, named WAP and GWAP, respectively. The antifungal and antibacterial activities of the peptides were analyzed using disk diffusion and turbidity measurement assays. The peptides in vitro exhibited effective antifungal activity against four plant pathogenic fungi at minimum concentration of 15 μg(protein) cm^-3. Their antimicrobial activity was negatively affected by the presence of 5 mM CaCl₂. The peptides were less effective against Gram-negative bacterium Erwinia carotovora subsp. carotovora, but they demonstrated inhibitory activity against Gram-positive bacterium Clavibacter michiganensis subsp. sepedonicus. The antimicrobial activity of GWAP was more effective than WAP.

Effects of phosphorus and thiourea application (either alone or in combination) were studied on clusterbean (Cyamopsis tetragonoloba Taub.) plants subjected to water stress by withholding irrigation at pre- and post-flowering stages in pot culture trial. Water stress significantly decreased shoot water potential, relative water content of leaves, net photosynthetic rate, contents of total chlorophyll, starch and soluble proteins as well as nitrate reductase activity at both the growth stages. Application of phosphorus and thiourea or combined application increased most of these parameters. Results revealed synergistic effects of P and thiourea in enhancing net photosynthesis, leaf area, chlorophyll content and nitrogen metabolism leading to significant improvement in plant growth and seed yield under water stress condition.

Fe deficiency was imposed in Citrus sinensis L. cultivars Valencia and New Hall grafted on C. aurantium and Swingle citrumelo rootstocks by the absence of Fe (-Fe) or by the presence of bicarbonate in the Hoagland nutrient solution. In Fe-deprived leaves total and active Fe concentration, and peroxidase and catalase activities were decreased while the ratios carotenoids/chlorophylls, P/Fe, and K/Ca were increased. Fe(III) chelate reductase activity was induced in (-Fe)-treated roots whereas it was depressed in bicarbonate-treated roots.

Cell cycle events in embryo axes of Norway maple (Acer platanoides L.) seeds were studied during dormancy breaking by flow cytometric analyses of the nuclear DNA content and by immunodetection of β-tubulin. Most embryonic nuclei of dry, fully matured seeds were arrested in the G₂ phase of the cell cycle. In addition, the lowest content of β-tubulin was detected in dry, mature seeds. Imbibition in water and cold stratification resulted in a decrease in the number of nuclei in G₂, and a simultaneous increase in β-tubulin content. In germinated seeds the content of β-tubulin was the highest and the number of cells in G₂ was the lowest. Both cell cycle events preceded cell expansion and division and subsequent growth of the radicle through the seed coat. The anatomical investigation has proved that the main reason for decrease in the number of nuclei in G₂ is mitosis, started with seeds germination (radicle protrusion). The activation of the cell cycle and the β-tubulin accumulation were associated with embryo dormancy breaking.

Salt stress (50 and 150 mM NaCl) effects on sucrose metabolism was determined in Lupinus albus L. Sucrose synthase (SS) activity increased under salt stress and sucrose phosphate synthase activity decreased. Acid invertase activity was higher at 50 mM NaCl and decreased to control levels at 150 mM NaCl. Alkaline invertase activity increased with the salt stress. Glucose content decreased with salt stress, sucrose content was almost three times higher in plants treated with 150 mM NaCl and fructose content did not change significantly. The most significant response of lupin plants to NaCl excess is the increase of sucrose content in leaves, which is partially due to SS activity increase under salinity.

The effect of radiation quality (350 - 740 nm) and darkness (D) on in vitro rooting, and chemical composition of the peach rootstock GF 677 was studied. Shoot explants were exposed for four weeks to cool white (control) (W), red (R), blue (B), green (G) or yellow (Y) radiation from fluorescent tubes. Some of the explants were kept in D during the rooting stage and others were maintained only for the first 2- or 4-d under R, B, G, Y or D, and subsequently were transferred to W. W was the most effective radiation source for adventitious root formation of GF 677 explants. Rooting was inhibited in those plants that remained in continuous D, and R reduced root growth in all treatments. The 2- or 4-d exposure to D, Y or B followed by W helped adventitious root development similarly as did W. G significantly increased Fe concentration in roots.

The in vitro cultures of the PR 204/84 peach rootstock (Prunus persica×P. amygdalus) produced the higher rooting percentage, mean root number, mean root length, fresh, and dry mass of roots when grown on media containing 88 mM sucrose or 88 mM glucose. Parafilm, rubber and aluminum foil as sealing materials were not significantly different in terms of rooting percentage, fresh, and dry mass of roots after 24 d in culture. The use of cotton as sealing material induced lower root number per shoot, length of roots, fresh, and dry mass of roots than the rest treatments.