We investigated diffusion of water in maize seedlings (Zea mays L. cv. Dnepropetrovskaya) following addition of polyethylene glycol (PEG) 6000 (osmotic potential -0.1 and -0.3 MPa) to the root medium by NMR method with pulsed gradient of magnetic field. Diffusion coefficients of different water phases in plant tissues (water of apoplast and vacuoles, water transported through the membranes) have been estimated from multicomponent decays of echo amplitude. Different signs of changes of water diffusion coefficients of fast and slow components of diffusional echo decay in roots and leaves under the influence of PEG-induced water deficits were shown. It has been supposed that under water deficit a sharing of water flows takes places through the different pathways (apoplastic, symplastic and transmembrane). In roots, 1-h water deficit increased the rate of fast diffusing water (water of apoplasm, vacuoles and, perhaps, water contained in intercellular endoplasm system), and decreased the rate of slowly diffusing water (water passing across the membranes). A long-term water deficit increased to a small extent the rate of water transmembrane transfer in root tissue. Leaf response to water stress was in the intensification of rate of transmembrane water transport that could be connected with the expression of water channels, and in the decrease of apoplastic water flow and flow along endoplasm. The possibility of estimation of plant tissue (membrane) integrity on the basis of diffusional data has been demonstrated.

Area of lesions produced by Colletotrichum orbiculare on watermelon (Citrullus lanatus) seedlings was not affected by amount of culture medium on which the fungus was grown, and decreased as length of time the fungus was in culture increased. Internal integrity of C. orbiculare spores appeared degraded, and this was coincident with decreases in lesion area.

The contents of endogenous gibberellic acid (GA₃), sugars, and dry mass in apical parts of fertile and sterile thalli of Chara vulgaris were estimated. The GA₃ concentration in the first node of fertile thallus, determined by capillary electrophoresis, was about 70.0 mg kg^-1 of fresh mass (f.m.). Pisum sativum-bioassay showed GA₃ concentration of 80.0 mg kg^-1 (f.m.) which was about 3 times higher than in the first node of sterile thallus. The higher amount of GA₃, glucose, and the lower starch content and dry mass in fertile plants than in sterile ones suggest the interdependence between fertility and contents of studied components.

Zea mays ssp. mays (2n=40) and Z. mays ssp. parviglumis (2n=20) were crossed to obtain hybrid plants by embryo rescue. Hybrid embryos were isolated and cultured on García et al. (1992) basic medium supplemented with 2,4-dichlorophenoxyacetic acid and/or kinetin in different concentrations. Caryopses harvested 23 d after pollination (DAP) were turgid, with 0.3 to 0.5 mm long embryos, while those harvested 30 DAP were shrunken, with 1 to 1.5 mm long embryos. Twenty days after plating, 100 % of the younger embryos gave rise to white, compact embryogenic calli. Subsequently, coleoptiles, leaf-like structures, shoots and roots originated from them and 35 hybrid plants were regenerated from 60 embryos. Embryogenic or organogenic calli frequencies did not differ among hormonal treatments, but they decreased, on average, from 90.5 to 44.3 %, comparing 50 and 120-d-old cultures. The older embryos regenerated plants only by germination, although they gave rise to organogenic callus with low frequencies. Regenerated plants showed a somatic chromosome number of 2n=30, pollen fertility of 40 to 80 % and 15 % viable naked caryopses.

Changes in ribonucleases (RNases), phosphomonoesterase (PME), phosphodiesterase (PDE), glucose-6-phosphate dehydrogenase (G6P DH), polyphenoloxidases, peroxidases and proteases activity and PR-proteins composition in leaf tissue and intercellular fluid (ICF) isolated from leaf tissue of healthy and TMV-infected hypersensitive tobacco (Nicotiana tabacum L. cv. Xanthi-nc) plants (non-inoculated leaves) were studied. The amount of the proteins and the enzymes of intercellular space was less than 3 % of the total amount of proteins and the enzymes found in homogenate of healthy leaves. The TMV infection did not significantly change this observation. The great increase in the activities of the enzymes was observed in homogenates of the infected leaves, especially of the enzymes involved in biosynthesis of precursors needed for virus multiplication (G6P DH, RNase, PME, PDE). This is in contrast with the activities of the enzymes of ICF, which were only partly increased. The ICF proteins of infected plants were separated by means of ion exchange chromatography on DEAE cellulose. The isozymes of peroxidase, polyphenoloxidase, PME and PDE were identified. Using discontinuous nondenaturating polyacrylamide gel electrophoresis of DEAE cellulose fractions, the detection of isozymes of peroxidases and PR-proteins was performed. By means of SDS-PAGE the molecular masses of PR-proteins were identified: 15 - 16 kDa (group 1), 27 - 28 kDa (group 3: chitinases) and 36 - 40 kDa (group 2a: β-1,3-glucanases).

The effect of five antibiotics: carbenicillin, chloramphenicol, cefotaxime, kanamycin and hygromycin on the organogenesis from callus cultures of Coryphantha elphantidens (Lem.) Lem. have been studied. Carbenicillin and cefotaxime stimulated shoot regeneration from callus. All antibiotics under study suppressed rooting of in vitro formed shoots. After five sequential subcultures on kanamycin supplemented medium, antibiotic resistant callus was obtained. To study the impact of kanamycin on resistant callus, total protein content was also studied. Selected callus showed a remarkable increase in callus mass. Antibiotic resistant plants have been selected by screening callus pieces on kanamycin supplemented media. Total protein content increased with subsequent subcultures in kanamycin resistant callus. The kanamycin selected shoots withstood the stability test after 2 months on antibiotic free medium. Plants were raised from the callus, which formed roots in 20 mg dm^-3 kanamycin, which was under study.

We studied the effect of water stress imposed at anthesis and pre-anthesis stages on oxidative stress and antioxidant activity in four wheat cultivars, two hexaploid Triticum aestivum cultivars, drought resistant cv. C 306 and drought susceptible cv. Hira, and two tetraploid cultivars, T. durum cv. A 9-30-1 and T. dicoccum cv. HW 24. Water stress decreased relative water content (RWC), membrane stability index (MSI), and increased H₂O₂ and malondialdehyde (MDA) contents as well as activity of superoxide dismutase (SOD), catalase (Cat) and peroxidase (POX) in all the genotypes at all the stages. Both the tetraploid cultivars showed higher RWC, MSI and SOD activity, and lower H₂O₂ and MDA contents under water stress than hexaploid ones. Cat and POX activities were highest in C 306.

Two spring barley cultivars, Golden Promise and Galan, were screened for callus induction and shoot regeneration from cultured immature inflorescences. Genotype Galan have better regeneration capacity in in vitro conditions than Golden Promise.

The goal of this study was the characterization of the antioxidative protection system of current and 1-year-old needles of a cembran pine (Pinus cembra L.) and its possible responses to elevated concentrations of atmospheric O₃. Twigs of a mature cembran pine at the alpine timberline (1950 m a.s.l.) were exposed in climate-controlled twig chambers for 91 d to charcoal-filtered air (CF), ambient air O₃ concentration (A), and two-fold ambient air O₃ concentration (2A). Additionally, a chamberless control group (AA) was used to examine chamber effects. At the end of the fumigation period the contents of free radical scavengers and photosynthetic pigments were measured in the needles. Independent from O₃ exposure, total ascorbate and α-tocopherol contents were higher in 1-year-old needles compared to the current flush while the opposite was found for glutathione. The amounts of pigments and antioxidants in P. cembra needles were comparable to those in other conifers growing at high-elevation sites. The only hint toward O₃ induced changes in the composition of antioxidants was an increase in the glutathione redox state toward more oxidation in 1-year-old needles upon exposure to A or AA conditions, but not upon 2A exposure. Chlorophyll and carotenoid contents were not affected by O₃ neither in current- nor in previous-year needles. The de-epoxidation state of the xanthophyll cycle pigments, however, was significantly increased in 1-year-old needles under A and AA compared to the CF control, but not under 2A. Hence, Pinus cembra, which is well adapted to the extreme environment of the timberline ecotone, exhibited only marginal biochemical changes in response to elevated O₃.

Sago, a processed (gelatinized) edible starch, was successfully used as a gelling agent in culture medium. The efficacy of sago-gelled (80 g dm^-3) medium was studied in ten potato (Solanum tuberosum L.) genotypes during micropropagation and minimal growth conservation. Sago starch provided a firm gelling surface throughout the entire culture period, and fostered optimum plantlet growth in terms of shoot height, number of nodes per plant, number of leaves and fresh mass. No softening of the sago-gelled medium occurred over prolonged (six months) storage. The study showed that sago starch could be used as a substitute to agar in culture medium to substantially reduce the medium cost.

In the course of a search for antifungal proteins from plant seeds, we observed inhibition of mycelial growth of Trichoderma viride with extracts of pearl millet. We have identified several proteins with antifungal properties in the seeds of pearl millet. One of these proteins has been purified to homogeneity and characterized. The purified protein has a molecular mass of 25 kDa. The N-terminal sequence of the protein (25 residues) shows homology to non-specific lipid transfer proteins (LTPs) of cotton, wheat and barley. The purified LTP inhibited mycelial growth of T. viride and the rice sheath blight fungus, Rhizoctonia solani in vitro.

Some maize (Zea mays L.) genotypes produced husk leaves without leaf blades. However, the physiological implication of this leaf deformity is unclear. Difference in protein pattern was observed between maize with and without husk leaf blades. A clear band around 38[sim ]40 kDa in seeds of maize genotypes without husk leaf blades appeared, while it was not detected in ones with husk leaf blades. These protein might be involved in leaf blade intiation.

Protein bodies (PBs) of European black pine (Pinus nigra Arn.) were isolated from mature seeds. Extracted soluble matrix proteins and crystalloid proteins PBs proteins were investigated by SDS-PAGE electrophoresis in presence and absence of 2-mercaptoethanol. The proteins of molecular masses 16, 17, 18, 61 and 65 kDa were presented only in crystalloid protein samples. Only 15 kDa protein was present in soluble matrix proteins and not in crystalloid proteins. Another protein bands were present in both soluble matrix and crystalloid proteins. 20, 37, 38, 39 and 48 kDa proteins were strongly visible among crystalloid proteins. Bands of 23 and 32 kDa were more visible in soluble matrix protein samples. Different composition in crystalloid proteins was found in absence of 2-mercaptoethanol: no proteins with molecular mass 71 kDa and more proteins in soluble matrix. In case of crystalloid proteins we detected 7 protein bands in interval from 71 to 212 kDa.

Cytosine methylation changes (hyper- or hypomethylation) in centromeric and telomeric sequences were observed in all three studied rice introgression lines containing DNA from wild rice, Zizania latifolia Griseb. The changed genomic Southern hybridization patterns were complex and non-concordant between a pair of isoschizomers (HpaII/MspI) digests, indicating methylation modifications at both the inner and outer cytosines of the CCGG sites. The changed patterns were inherited through generations. Possible mechanism for the methylation changes and their potential implications for the phenotypic variation and genome organization are discussed.

Structure of callus cells of frost-sensitive and frost-tolerant Solanum species and a frost-tolerant cell line (D20-1), selected from S. tuberosum cv. Desirée callus, was studied. Like frost-tolerant species S. commersonii, cells of the frost-tolerant cell line contained starch grains in their plastids. The cells of this frost-tolerant line also possessed an increased number of microbodies containing protein crystals which suggests the involvement of proteins in frost tolerance but the mechanism may differ from that in frost-tolerant species.

In vitro salt tolerant rice plants established by step up treatment with 0.5, 1.0, 1.5 and 2.0 % NaCl at 3-week intervals were examined to determine whether they could grow in potted paddy soil containing 0, 0.55 or 0.75 % NaCl till harvesting. All the control plants were necrotic by the 4^th week in the culture. At the 10^th week of culture, 100 % of the salt-tolerant plants subjected to 0 or 0.55 % NaCl survived, and 78 % of the plants at 0.75 % NaCl. The Na⁺ and Cl^- contents in the leaves of salt-tolerant plants grown at 0.55 and 0.75 % NaCl were about 4 times of those without NaCl. The ion contents in non-tolerant plants and seedling plants were 10 to 12 times of those in 0 % NaCl treatment. One of the hypotheses to explain the present data is that the in vitro step up salt selection induces the capability to maintain no lethal concentration of NaCl in the leaves.

Nitrate and total nitrogen contents, and nitrate reductase (NR) activity of the excised maize roots in buffered or unbuffered nitrate solution (at pH 6.5 or 4.5) as affected by putrescine (PUT), abscisic acid (ABA) and salicylic acid (SA) were investigated. In unbufferred solution, the NR activity was lower at pH 4.5 as compared to that at pH 6.5, but in bufferred solution the activity was higher at lower pH. Supply of 100 µM PUT or 500 µM SA, promoted NR activity and 50 µM ABA inhibited the activity at pH 6.5. However, at pH 4.5, PUT and SA inhibited NR activity and ABA had no effect. In most cases, the increase in NR activity was positively correlated with total organic nitrogen and a negatively with nitrate content. A reverse situation was found when NR activity was inhibited by the growth regulators.

Inheritance of chloroplast DNA (cpDNA) was examined in 41 F₁ progeny obtained from the following interspecific Bromus crosses: Bromus arvensis (2n = 14) × B. inermis (2n = 4x = 28); B. arvensis × B. inermis (2n = 8x = 56); B. arvensis × B. erectus (2n = 6x = 42); B. arvensis × B. erectus (2n = 8x = 56); B. arvensis × B. erectus (2n = 10x = 70). Chloroplast DNA of the parental species was digested with BamHI, EcoRI and HindIII and species-specific restriction fragment length polymorphisms were identified by observation of ethidium bromide stained agarose gels as well as by filter hybridization experiments involving heterologous cloned barley cpDNA probes. The stability of these point mutations was verified by examining the cpDNA restriction patterns of at least 28 individual plants raised from seed of each of the parental species. No intraspecific cpDNA variability was detected. All the F₁ progeny examined exhibited the cpDNA restriction fragment patterns of the female parent. There was no evidence of any paternal or biparental cpDNA inheritance. The results provided evidence for the uniparental-maternal inheritance of cpDNA in the Bromus crosses examined.

The effects of Cr and Co supplied either individually or mixed together in the nutrient solution on seed germination, enzyme activities, photosynthesis, metabolic products, and yield were investigated. Cr and Co reduced germination percentage only at the highest concentration used but markedly decreased radicle growth which might be attributed to depressive effect of Cr and Co on the activity of amylases and subsequent transport of sugars to the embryo axes. Protease activity, on the other hand, increased with the metal treatment. The highest concentration (10^-2 M) tested of both metals was harmful on plant growth, while the low and moderate concentrations (10^-6 and 10^-4 M) enhanced the contents of chlorophylls and sugars, and activity of Hill reaction. Fresh mass of the produced pods increased at low and moderate concentrations of Cr and at Cr+Co treatment, but decreased in plants treated with Co.

The dependency of radicle elongation in Abies numidica somatic embryos on germination media has been studied. No significant differences were detected between the Murashige and Skoog (MS) and Schenk and Hildebrandt (SH) medium. The addition of 10 g dm^-3 activated charcoal or 0.05 mg dm^-3 indole-3-butyric acid (IBA) into both media had positive influence on embryo germination. Difference between activated charcoal and IBA effects were significant. The high rooting percentage (85 %) was recorded on half SH medium with 10 g dm^-3 sucrose and activated charcoal. After IBA addition rooting percentage was increased to 95 %. During 7 months 73 % of plantlets survived transfer to soil and in 54 % of plantlets shoot growth was observed.