Potato plants were transformed by the A.tumefaciens vector which integrates into the plant genome two foreign genes only: pTi C58 T-DNA gene 4 (ipt) responsible for elevated synthesis of cytokinins and kanamycin resistance gene. Three teratoma clones studied showed approximately 3 times, 6 times and 9 times increased levels of zeatin riboside and zeatin in comparison with untransformed controls and slight increase of the IAA level. Shoots formed roots in agar cultures sporadically, if the increase of zeatin riboside and zeatin levels was not higher than 6 times the control level. The chlorophyll content and net photosynthetic rate decreased with increasing levels of zeatin and zeatin riboside.

Spontaneous recovery of regeneration abilities was observed in a long-term (about two-year-old) crownvetch (Coronilla varia L.) tissue culture permanently grown on MS medium containing 1 mg 1^-1 IAA. Somatic embryos and later complete plants differentiated from initially regenerating roots. The formation and development of embryos was accompanied by a 10- to 20-fold increase in the content of cardioactive glycosides hyrcanoside and deglucohyrcanoside in the culture biomass. The effect of auxins (IAA, NAA, 2,4-D) and cytokinins (6-BAP) on calogenesis and somatic embryogenesis was examined; further development of somatic embryos was enhanced by light. Primary explants which were newly isolated from sterile R₁ plantlets showed differential, organ-specific ability of somatic embryogenesis which was highest in root cuttings. Regenerated plants were transferred to field culture; two-year-old cultures of regenerated plants showed in most cases phenotypic deviations from the original material, especially dwarfism.

Transpiration rate, stomatal frequency, growth, contents of pigments, saccharides, total nitrogen, proteins and some nutritive elements (K, Ca, Mg, P) of radish plants were significantly lowere dwith the rise in salinization levels using NaCl. Spraying radish shoots with proline solution (200 g m-³) counteracted the above adverse effects, especially at low and moderate salinity.

The effects of salicylic acid (SA) and other phenolic compounds, acetylsalicylic acid (ASA), benzoic add (BA) and sulfosalicylic acid (SSA), on ethylene production and somatic embryogenesis by carrot (Daucus carota L.) cell cultures were studied. SA and ASA, at concentrations of 10 μM and 100 μM, significantly stimulated somatic embryogenesis and effectively inhibited ethylene production by carrot cell suspension cultures. The observed increase of embryo number was proportional to the inhibition rate of ethylene production. However, BA and SSA affected neither ethylene production nor somatic embryogenesis. The role of SA in somatic embryogenesis is discussed.

Samples of the same kind (rape leaves, wheat crowns, onion bulbs or spruce needles) killed by a slow freeze-thaw cycle or by immersion in liquid nitrogen showed a similar time course of leakage. Leakage was accelerated in treatments when the sample, immersed in water, was killed by heating for 5, 15 or 30 min in a boiling water bath. The longer the boiling, the sooner the maximum conductivity (L_km) was obtained. The L_km did not depend on the way of killing but in samples killed by freezing, it was achieved after a longer leakage time. The leakage rate decreased from onion to rape, wheat and spruce. The relative conductivity [%] allowed a better comparison of various treatments and of samples of different kinds of tissues than the specific conductivity [μS cm^-1].

Callus cultures were initiated from the bud apices of 10-40-year-old Scots pines (Pinus sylvestris L.) at different seasons and maintained on modified MS medium without subculturing. Separate sets of experiments were used for analyses of carbohydrate content, ethylene production, amino acid composition, protein patterns andin vitro translation. In each case the change in the colour of the calli was recorded and the fresh mass of the samples measured. The onset of tissue browning was found to be associated with changes in protein pattern, amino acid content, ethylene production and the occurrence of sucrose and accumulation of starch.In vitro translation experiments using poIy(A)⁺ RNA isolated and purified from the calli indicated that the switch in metabolism accompanying browning is paralleled by activated protein synthesis. Thus, the development of brown colour does not as such seem to be harmful to the tissue. The later, more intense tissue browning and deterioration which is reflected in a reduced capacity for protein synthesis and changes in the free amino acid pool and protein pattern is probably a secondary phenomenon.

The effect of water stress induced by application of polyethylene glycol 6000 during seed germination and seedling growth ofOryza sativa L. cv. IAC 165 was analysed. The seed germination was inhibited by the decrease in the water potential of the medium, the inhibition being greater under white light than under continuous darkness. When the seedling was submitted to water stress (-0.51 MPa) white light inhibited growth of root, coleoptile-and leaf, while under no stress conditions white light caused increase in growth of root and leaf and only inhibition of coleoptile growth.

The content of auxin-, inhibitors-and gibberellin-like substances in freeze-dried humic acids was studied. The results indicate the existence of growth-promoting substances in humic acids, possibly corresponding to IAA or its precursors. Inhibitory activity is more marked during germination than during the growth process. The inhibitory effect caused by high concentration of humic acids could be due to an auxin-like action rather than an input per se of growth inhibitors. A significant amount of both free and conjugated gibberellin-like substances were observed.

Aminopeptidase, carboxypeptidase and proteinase activities were measured in endosperms from unripe and ripe seeds of ×Haynaldoticum sardoum. Aminopeptidase and proteinase activities were high during the early maturation stages and then decreased. In contrast, carboxypeptidase activity increased with maturation.
Localization studies demonstrated that aminopeptidase and carboxypeptidase activities were present in the three tissues examined (pericarp, green layer plus aleurone, and starchy endosperm). Proteinase activity against gliadin was located in the pericarp and in the green layer plus aleurone, but was absent in the starchy endosperm.
The presence of proteolytic activities in the outer kernel layers might be correlated to the hydrolysis of transitory protein reserves during the senescence of the seed coatś.
Aminopeptidase and carboxypeptidase activities located in the starchy endosperm could participate in the breakdown of protein reserves during the early phases of seed germination.

The equilibrium density of chloroplasts from barley (Hordeum vulgare L. cv. Hassan) was analyzed by sucrose gradient centrifugation. Natural and detachment-induced leaf senescence were associated with a decrease in density and an increase in heterogeneity of the chloroplast population. Treatments (with growth regulators and light) which retarded or accelerated senescence, respectively, retarded or accelerated chloroplast density decrease. Accelerators as well as retardants of senescence decreased the heterogeneity of the chloroplast population.

Influx and efflux of inorganic phosphate was determined in freshly cut and "aged" slices of sweet potato tubers, in the presence or absence of abscisic acid. Slices aged in the phytohormone took up considerably less phosphate than did the control slices. No difference in the rates of uptake of phosphate by the fresh tissue was observed. Kinetics of uptake of the aged untreated slices, proved to be bi-phasic. This was not the case for the treated slices. Neither the treated nor the untreated uptake curves for the fresh slices were bi-phasic. Efflux of phosphate from the slices aged in abscisic acid was greater than from the untreated slices. The results strongly suggest an effect of abscisic acid on the cell membrane.

Regeneration abilities of buds on shoot segment explants isolated from adult trees of oak (Quercus robur), aspen (Populus tremula), black locust (Robinia pseudacacia), Japan pagoda tree (Sophora japonica), and English walnut (Ailanthus glandulosa) were studied during the growing season. Optimum BAP concentrations for the regeneration of oak bud meristems were dependent on the date of sampling. Axillary shoots could be induced from winter and summer buds of oak and aspen on Dustan and Short media supplemented with activated charcoal and BAP at concentrations from 0.5 to 2 mg 1^-1. More intensive rooting of segments of newly formed shoots was observed on MS medium diluted to one half and supplemented with 2 % sucrose and 0.2 mg 1^-1 of IBA.Populus tremula formed longer axillary shoots on DS media supplemented with 0.5 mg 1^-1 of BAP and 1 mg 1^-1 of GA₃.
Regeneration capacities of black locust, Japan pagoda tree, and English walnut were higher. In addition to the induction of multiple shoots from buds, shoots could also be obtained from calluses formed on basal segment parts. Asparagine and glutamine at a concentration of 25 mg 1^-1 stimulated the percentage of differentiated stems on callus surface. Inhibitory effects of substances which accumulated in buds in the second half of the growing season could be reduced by means of pulse treatments in 50 mg 1^-1 BAP solutions or using short-term dipping into 0.1 % AgNO₃ solution.

Organogenic callus cultures ofPapaver somniferum L. were studied with the aim of describing the morphology of the callus and observing the changes occurring during differentiation and induction of organogenesis. The morphology of the cells and the formation of meristemoid areas were studied on a light microscopic level. Histological evidence showed that from the inner meristematic centres, protracheal elements are differentiated, from the surface meristematic centres meristemoids are formed and therefrom green leaf-like organoids.

Phaseolus coccineus storage globulins were extracted from mature cotyledons, purified and characterized. Three major proteins were separated. A component showing erythroagglutinating activity was thoroughly purified by thyroglobulin-Sepharose chromatography. The relative molecular masses of the three fractions are Mr = 330, 178, and 500 kDa as determined by polyacrylamide gel electrophoresis (PAGE). They correspond to the proteins found in other systems and classified as phytohaemagglutinin (PHA), vicilin and legumin, respectively. Electrophoretic analyses under denaturating conditions (SDS-PAGE) evidenced the major subunits for the three proteins. Isoelectrofocusing of the isolated proteins indicated a large heterogeneity for vicilin.

The study deals with the effect of indol-3-ylacetic acid (IAA) on endogenous rhythm of flowering inChenopodium rubrum L. ecotype 374. Phase setting of the rhythm and length of its period were not affected, its amplitude decreased or changed insignificantly depending on the time and the site of IAA application. The intervals of significant inhibitory effect of IAA applied to apical buds terminated later than after IAA application to photoreceptive organs. The inhibitory effect did not correlate with the level of IAA uptake. Results obtained support the hypothesis that both photoreceptive organs and apical buds are the sites of inhibitory effect of applied IAA.

In the long-term cultivated callus cultures ofMatricaria recutita L. the identical concentration changes in the biosynthesis of glutathione, glutamate, aspartate, total thiols and proteins were detected within the subculture. The level of oxidized glutathione during the growth of callus culture was low with the highest value 10.66 nmol g^-1 on the 13th day of subculture. The ratio GSH/GSSG which significantly influences the redox processes in a cell, and the activity of glutathione reductase increased from the 8th day. Ascorbate formation was detected on the 17th day, although no relation between the ascorbate synthesis and the concentration of glutathione and glutathione reductase was found.

Continuous treatment with spermidine or 1-aminocyclopropane-1-carboxylic acid stimulated ethylene production and ethylene-forming enzyme activity and accelerated chlorophyll breakdown in detached tobacco leaves. The treatments also induced the production of eleven major acidic pathogenesis-related proteins, which were also produced during the hypersensitive reaction to tobacco necrosis virus. A delay between the onset of the stimulated ethylene increase and the detection of PR-proteins was found; ethylene production was stimulated after a few hours of treatment, whereas one, three and all the eleven PR-proteins were detected by polyacrylamide gel electrophoresis of fluid extracts after 2, 4 and 6 days of treatments, respectively. The possible causal relationship between stimulation of ethylene production and PR-protein accumulation is discussed.

The growth of primordia of marginal buds (marginals) which differentiate on leaf margins is correlatively inhibited on intactBryophyllum crenatum plants. Following leaf isolation, the marginals are released from this correlative inhibition, which process is accompanied within 2 to 10 h after leaf isolation with a decrease in the content of endogenous IAA in the leaf blade. This decrease can be enhanced by transversal cutting of the leaf blade into three parts which also results in enhanced subsequent growth of the marginals. The growth which follows after the release of the marginals from correlative inhibition is accompanied in cut leaf blades with an increased content of endogenous IAA in the period from 12 h to 7 d after leaf isolation when compared with uncut leaf blades. The highest content of endogenous IAA was recorded in the middle section, and the lowest IAA content in the basal section of the leaf blade.

Lead was detected and located in definite regions of thePopulus adventitious roots with the light microscope. Incubations of 24, 48, and 72 h in solutions of Pb(NO₃)₂ resulted in clear sequences of microscopic images. Interpretation of these images allows the construction of a scheme for lead transport pathways in roots.

Changes in macromolecule syntheses, especially RNA synthesis, and the energy providing system were investigated in seeds ofAgrostemma githago aged for different periods. In embryos of aged seeds all macromolecule syntheses start later and reach a lower level than young ones. It was found that the synthesis of rRNA in embryos of aged seeds is reduced whereas the synthesis of poly (A⁺) RNA in relation to the total RNA synthesis is highly increased as well as the amount of this RNA species with long poly (A) chains. The results are discussed in connection with the decreased protein synthesis and the reduced ATP content and ATP formation ability in embryos during the long time storage of seeds.

The inheritance of the gliadin spectra in F₂ hybrids between cultivars hexaploid wheat Bezostaya 1 and Bisel has been investigated. The results from the electrophoretic examination and analysis of the gliadin spectra reveal that the components 1,2,3,11 and 15 from the Bezostaya 1 spectrum and 1,2, 3, 7,11 and 15 from the Bisel spectrum are controlled by allelic variants of one gliadin coding locus in 1D chromosome.

Protein complex patterns of cloves and esterase isoenzyme patterns of apical buds of cloves were studied with Czechoslovak virus-free cultivars ofAllium sativum L. and the wild speciesA. longicuspis Regel, Similarly, four clones-regenerants obtained using explant culture techniques from A.sativum L. cv. Bzenecký paličák (two somaclones and two clones derived from plants regenerated from meristem cultures treatedin vitro with colchicine) differing in their ploidy, morphology, and yields were studied. Immunophoreograms of protein complexes of theA. sativum L. cultivars under investigation differed from one another in the number and mobility of protein fractions in both the cathodic and anodic regions and thus these cultivars can be distinguished. On the basis of esterase isoenzyme patterns, the Czechoslovak cultivars of A. sativum L. can be arranged into three groups - bolting winter cultivars with broad leaves, non-bolting winter cultivars with broad leaves, and non-bolting spring cultivars with narrow leaves. All the clones-regenerants showed the same protein complex and esterase isoenzyme patterns as their original cultivar.A. longicuspis Regel markedly differed in its protein complex and esterase isoenzyme patterns from all the other genotypes studied.Received May 17, 1989: accepted January 5,1990