Vitrification of stem explants of carnation was brought about by culturing in liquid medium. Cellulose and lignin levels were decreased in vitrified stems and leaves. Isolated cell walls of vitrified tissues were also characterized by low calcium content, low Ca²⁺/uronic acids ratio, low ratio of uronic acids to neutral sugars due to higher amounts of the latters. All these characteristics may account for the high wall plastic potential previously measured in vitrifying internodes.

Different species of yam tubers were examined for the presence of pyruvate kinase and phosphatase activities, Pyruvate kinase was purified 25 fold with a yield of 50 %. using ammonium sulphate precipitation and ion exchange chromatography on DEAE-Sephadex. Partially purified enzyme showed normal Michaelis-Menten kinetics. However, pyruvate kinase from crude extract of dormant yam tuber showed slight sigmoid response towards phosphoenol-pyruvate and magnesium and to a certain extent ADP. The enzyme is activated by AMP and inhibited by ATP and citrate in both crude and partially purified preparations. Further studies on the effect of energy charge on the enzyme strongly suggest that pyruvate kinase from D. alata is a regulatory enzyme. No evidence was found for the presence of more than one pyruvate kinase in germinating D. alata tuber. With the exception of D. dumentorum, all the other three species of yams studied contain very little or no detectable phosphatase activity during dormancy. However, phosphatase activity increased during germination in all the species, thus excluding the use of sprouting yam tubers for kinetic study of pyruvate kinase.

Uptake of³⁵S-sulphate by bundle sheath strands (BSC) from leaves of maize plants (Zea mays L. ev. Dekalb L 72 A) was higher than that by isolated mesophyll protoplasts (MC) of maize. Ion uptake followed the Michaelis-Menten kinetic satuiation curves. SO² ₄-uptake increased after addition of malate, NADPH, malate + NADP+ to BSC suspensions, but not to MC susp: nsions.

Recurrent application (17 administrations in 38 days) of 14 pesticides (Karathane FN 57, Fundazol 50 WP, Dithane M 45, Topsin M 70 WP, Perozin 75 B, Fademorf EK 20, Novozir MN 80, Metation E 50, Pirimor DP, Decemtion EK 20, Zeazin 50 DP, Fatex EK 80, maleic hydrazide and Ethrel) did not increase (with the exception of maleic hydrazide) the frequency of somatic mutations in a heterozygous chlorophyll mutant ofNicotiana tabacumL. var.xanthi n. c. None of the four tested pesticides (Fademorf EK 20, Decemtion EK 20, maleic hydrazide and Ethrel) were transformed in tobacco plants to a stable mutagenic or promutagenic product active in theSalmonella (Ames) mutagenicity assay.

Crown galls and hairy roots were induced inin vitro cultivated seedlings ofAtropa belladonna by differentAgrobacterium tumefaciens andA. rhizogenes strains. During furtherin vitro cultivation, tumors and hairy roots showed high differentiation ability which persisted for at least one year ofin vitro culture. Only root cultures, induced by Ri plasmid A4, synthesized detectable amounts of alkaloids.

Effect of abscisic acid on cell permeability in leaves ofIresine u allisi hort. and roots ofBeta vulgaris L. were examined. An increase of betacyanin leakage from leaf cells was shown by ABA at 10^-4, 10^-7 or 10^-9 M concentrations in water solution at 25 °C. The efflux of batacyanin from tissues did not change during the joint action of ABA and PEG 1000. ABA could lower the betacyanin leakage fromIresine leaves and beet-root slices under severe osmotic stress, as was found by deplasmolysis. The results suggest that ABA elicits some alteration in density of tonoplast membranes under dehydration.

Methyl jasmonate (JA-Me) at a concentration of 0.5% in lanolin paste totally inhibited bulblets formation induced by benzyladenine in intactMuscari bulbs. Lower concentrations of JA-Me delayed development and growth of bulblets induced by benzyladenine. It seems that methyl jasmonate acts as a powerful inhibitor of cell division induced by cytokinin in used test. In comparison with methyl jasmonate, abscisic acid did not show an inhibitory effect on bulblets formation induced by benzyladenine, even in a higher concentration.

A cabbage variety with particularly strongly developed leaves and extremely shortened stems (tight heads) was treated during the first year of its development with growth retardants (CCC and CEPA, Ethephon) at different concentrations. A 4-fold treatment with CCC, CEPA or a mixture of both proved to be most effective Leaf growth was inhibited by this treatment (head mass decreased) but stem growth increased. Only in treated plants the bud of the stem apex could break through the leaf sheath and develop generative stem. The results are discussed as examples of correlative relations between leaf and stem growth.

Diurnal changes in K content in leaf blades, petioles, stems and roots of eleven lucerne genotypes were followed. Significant positive correlations between changes in K content in petioles and upper half of stems and significant negative correlations between changes of K content in leaf blades and lower half of stems reflected rapid K movement. The velocity - up to 60 μmol g-1 (f.m.)h-1 - of changes in K content from leaf blades to lower part of stems and the other way round showed that long distance phloem transport occurred. Only moderate increase of K content contemporarily took place in roots. When total K amount in the whole plant was calculated then K uptake alternatively with K release were noticed during the day. Average K release reached 1.48 μmol g-1 (f.m.) h-1. The rate of K movement correlated with irradiance and physiological activity of plants. The time course of K movement was uniform in plants of the same strain and it differed partially in different strains.

IAA oxidase, catalase and peroxidase activities of seedlings (the first day of radicle emergence) or organs of young plants (the fifth day of radicle emergence) germinated in NaCl media (0, 25, 50, 100 or 150 mM) were measured. Three species with successively lower thresholds of salinity sensitivity were measured: tomato, radish and red cabbage. NaCl sensitivity of the above enzymes was also analysed in extracts from control seedlings or plants incubated in media with different NaCl concentrations. No relation was found between enzyme activities and protein levels or Na contents of young plants; on the contrary, a good relation was observed between enzyme activity and Na contents of seedlings. Oxidase activities have similar NaCl sensitivity in the three seedlings. Comparing the enzyme activity and sensitivity with NaCl tolerance of the species, the consequences of the oxidase activities in young plants germinated in NaCl media are discussed.

Methyl jasmonate (JA-Me) at concentration of 0.5 % and 1.0 % in lanolin paste applied to the surface of postclimacteric apples cultivars McIntosh, Spartan, and Cortland inhibited ethylene production in slices of cortex with a skin cut to a depth of about 2 mm. The level of 1-aminocyclopropane-l-carboxylic acid (ACC) was decreased in tissues of apples treated with methyl jasmonate. Methyl jasmonate stimulated ethylene production in preclimacteric apples cv. McIntosh.

The effect of indol-3-ylacetic acid, gibberellie acid, kinetin, abscisic acid and Ethrel on the growth of mycelium, sporulation and germination of spores ofFusarium culmorum of different pathogenicity to wheat seedlings was studied. The production of gibberellins, auxins, cytokinins, ethylene and growth inhibitors by these isolates was determined as well. It has been found that most pronounced and explicit effect on growth and development in fungi was produced by Ethrel which strongly inhibited these processes. ABA proved to be a strong growth and development stimulator, though to a different extent in different isolates. GA₃ strongly stimulated sporulation and spore germination in some isolates. The effect of IAA and K on growth and development in fungi was slight. More sensitive to growth regulators were the fungi in earlier stages of growth. No correlation between the pathogenicity of the isolates and their ability to produce growth regulators as well as between their susceptibility to exogenous growth substances in the processes of fungal growth and development was stated.

DNA-dependent RNA polymerase II (nucleosidetriphosphate: RNA nucleotidyltransferase, EC 2.7.7.6.) from duckweed Wolffia arrhiza (L.) HORKEL ex WIMMER was partially purified by polyethylenimine precipitation and DEAE cellulose ion exchange chromatography. Whole plants were irradiated with red light pulses. After a dark period of 2 to 12 h there is no effect of light pretreatment on the total or specific activity of the purified enzyme.

The effect of methyl jasmonate (JA-Me) applied in concentration 1.0 % in lanolin paste to detached tomato fruits at the mature green, advanced mature green and light red stages on the ethylene production and l-aminocyclopropane-l-carboxylic acid (ACC) content was investigated at different times after treatment. JA-Me stimulated ethylene production in all stages of ripening, but the level of ACC increased or decreased in comparison with control depending on the stage of ripening. Higher level of ACC in JA-Me treated tissue was found in mature green stage and fully ripened tomatoes-treated at advanced green stage; lower one in light red stage - treated at advanced green stage and fully ripened stage - treated at light red stage.

Green islands were observed around infection spots ofAlternaria brassicicola on mustard leaves in nature. These green islands had higher cytokinin-like substances as compared to surrounding yellowed tissue and healthy tissue. Presence of starch in green islands has been correlated with formation of metabolic sinks in green islands, because of higher cvtokinin-like substances in them.

This article reports the effect of cold storage at 4 °C from December to April on chestnut cuttings. Rooting was found to increase after four months preceded by treatment with 4000 mg l^-1 IBA.
ThePhaseolus test of the biological activity of extracts of the cuttings showed the inhibition exerted by the acid fraction of the fresh (December) cuttings to have been replaced by a rootpromoting effect in cuttings stored for 4 months at low temperature. Cold storage thus seems to favour rooting.

Anodic oxidation of coumaric acid led to the inhibition of the process at the electrode due to a film which was formed after one-electron oxidation of the acid to phenoxy radical.By contrast, caffeic acid is oxidized in two steps-the phenoxy radical is formed in the first step, quinone in the second step. The inhibition of nitrate uptake by coumaric and caffeic acids is dependent on their concentration. 10^-4 M eaffeic acid totally inhibited nitrate uptake and the growth ofNicotiana tabacum cell suspension. 10^-6 M caffeic acid markedly inhibited nitrate uptake especially in the first three days after inoculation. 10^-6 M coumaric acid did not affect nitrate uptake and nitrate reductase activity, 10^-4 M coumaric acid inhibited nitrate uptake by day two after inoculation. Nitrate reductase synthesis correlated with the inhibition of nitrate uptake. Differential effects of coumaric and caffeic acids are explained on the basis of different products of their electrochemical oxidation.

The content of phenolic substances in the cell suspension culture ofCentaurium erythraea fluctuated during a 21-day-long subcultivation period in dependence on the growth phase. The total relative content of the phenolics reached its maximum at the time of transition to the exponential growth phase, similarly as the fraction of free phenolic acids, glycosides, and the fraction of phenolic acids released from the cells after alcaline hydrolysis. On the other hand, the content of phenolic acid esters decreased at this growth phase of the culture. Changes in the level of phenolic substances in the culture medium corresponded in their character to changes in the relative content of the phenolics in the cells.