Between 1986 and 1989 we studied the influence of γ-irradiation (2.5-80 Gy) on growth processes and the content of arbutin glycoside. Bearberry [Arctostaphylos uva-ursi (L.) Sprengel] shows polycyclic characteristics of growth; the vegetation period is divided by summer dormancy (June) into periods of spring and summer growth. As plants age the summer dormancy gets longer and the period of summer growth is shorter. Irradiation with a dose of 80 Gy was lethal and a dose of 60 Gy damaged plants so much that they were not able to grow in the first spring after irradiation. Significant growth stimulation (both in the height of plants and in branching) was shown only in the second year after irradiation (2.5-60 Gy). In the fourth year the growth in all irradiated variants was weaker than in the control. Doses of 2.5 and 5 Gy did not influence the content of arbutin significantly; higher doses of irradiation changed the dynamics of production and decomposition which is connected with growth changes.

Eleven genotypes of sunflower were used to screen their regeneration potential in a meristem regeneration test. The inbred line HNK-81 showed the best regeneration of shoots directly from apical meristems and meristem derived calli, and rarely also the formation of adventious shoots from leaves of regenerated shoots.

Floret pieces prepared from the methanol-treated and air-dried flowers of safflower (Carthamus tinctorius L.) were subjected to an enzymatic hydrolysis in a buffered solution and the rate of precarthamine solubilization was assessed spectrophotometrically. The amount of precarthamine was risen by treating the floral pieces with a β-glucosidase (EC 3.2.1.21), supporting a previous assumption that precarthamine is in the floral tissues associated with cellular components. The enzyme activity was reduced by various inhibitors. On the basis of the experimental data, it is proposed that the precarthamine may be bound through 0-β-glucosyl linkage(s).

The intracellular enzyme activities ofChlorophyllum molybditis (Mayerex. Fr.) Massee andCortinarius melliolens Fries were determined at different stages of sporophore maturity. In both mushroom species, total amylase, α-amylase, proteinase, lipase, peroxidase, catalase and polyphenol oxidase activities were increased with sporophore maturity. In contrast, glucose-6-phosphatase activity was higher in the young sporophore than in very young and mature ones. All the enzymes assayed except cellulase and β-amylase showed greater activity in the pilei than in the stipes.C. molybditis showed greater total amylase, α-amylase, cellulase, proteinase, catalase and glucose-6-phosphatase activities thanC. melliolens.

The full length cDNA clone of leghemoglobin I gene fromLupinus luteus was placed under dual promoter into the plant expression vector pCB1399 and the resulting vector (pCB1415) was transfered into theAgrobacterium strain LBA4404 (pAL4404). The binary system LBA4404 (pAL4404, pCB1415) was then used for transformation ofNicotiana plumbaginifolia andLotus corniculatus. In both species kanamycin-resistant plants have been selected and regenerated. The synthesis of LbI protein in transformed plants has not been shown.

Hypocotyls of seedling plants of the sunflower inbred line HNK-81 were used as a source of protoplasts. Optimal conditions of isolation and culture of protoplasts were established. Using the method of individual culture in microdrops, a 77% final plating efficiency was achieved. Cytokinins, especially zeatin, showed a significant influence on the formation of globular embryo-like structures, but these failed to develop into mature embryos. Calli obtained in liquid media containing auxins and cytokinins grew on agar solidified media without growth regulators.

The fatty acids composition of the polar and non-polar lipid fractions of wheat leaves was affected due to progressive brown rust infection during early stages of pathogenesis,i.e. 0, 12, 24, 36, 48 and 72 h after inoculation. The three races ofPuccinia recondita differentially affected the composition of saturated and unsaturated fatty acids and their relative occurrence in wheat leaves. The infection of wheat by race 77 resulted in a relative decrease in fatty acid chain length as measured through C₁₆∶C₁₈ fatty acid ratio. An increase in the relative degree of unsaturation (18∶2/18∶3 acids ratio) was recorded in both lipid fractions. Such changes may be taken as one of the earliest characteristics of disease development.

Chlorophyll (Chl) synthesis in isolated Scots pine embryos depended on exogenous application of cytokinin (CK) and Ca²⁺. At a constant benzyladenine (BA) level (4.4×10^-5 M) 10^-4 to 10^-2 M Ca²⁺ concentrations in mineral medium were optimum for Chl biosynthesis under both light and dark. At a zero or very low (10^-6 M) concentration of external Ca²⁺, Chl synthesis was relatively more Ca²⁺-dependent in embryos cultured in darkness than in the light, which suggested that the light: (a) stimulated the transport of Ca²⁺ from external sources to cytosol, and/or (b) interacted with Ca²⁺ directly in the pathway of Chl biosynthesis. The need of external Ca²⁺ was evidenced in experiments with modulators of Ca²⁺-transport systems. The reduction of the inward current of Ca²⁺ from readily accessible external sites by chelating agent (ethylene glycol-bis (beta-aminoethyl ether-N,N,N'N'-tetraacetic acid, EGTA) and Ca²⁺-channel blockers canceled the formation of Chl. The effect of EGTA depended on the level of external Ca²⁺. Inhibitory action of Ca²⁺-channel blockers depended on their kind and concentration: at the 10^-5 M concentration La³⁺>verapamil>nifedipine inhibited Chl formation. In the presence of Ca²⁺, the Ca²⁺-agonist A 23187 mimicked the BA effect and about 92% of Chl was synthesized as compared with the BA variant. Low concentrations of calmodulin antagonists reduced the amounts of Chl. Calmodulin was included in a second messenger system for BA action in promoting Chl biosynthesis in isolated Scots pine embryos.

The angiosperm root parasiteCynomorium coccineum and the halophytic hostsLimonium delicatulum andArthrocnemum glaucum were invesrigated under natural conditions in a Mediterranean salt marsh in March 1992. The diurnal transpiration rate of the parasite was low and parallel to the climatic factors. The non-infected plants showed higher transpiration rates than the parasite and its hosts. Compared to the non-infected plants, it is apparent that the perennial herbL. delicatulum is more sensitive to infection since its reduction in the fresh and dry mass was higher than that found inA. glaucum.

Forward streptomycin-resistant mutations and reverse mutations at the ARG7 locus after UV irradiation were studied in two photoreactivation-deficient mutants ofChlamydomonas reinhardtii, Phrl and Phr2. The mutant Phrl was more mutable than Phr2. Caffeine increased survival and reduced mutation rate of streptomycin-resistant mutations induced in both photoreactivation-deficient strains. Two different alleles of ARG7 locus (arg2 and arg7) were introduced into photoreactivation-deficient mutants. It was found that in the presence of both alleles, the frequency of mutants resistant to streptomycin was reduced. The reduction was more remarkable in the presence of arg2. But also under these conditions Phr1 was more mutable than Phr2.

A fast and efficient method for the isolation of major late heat-shock protein (HSP89) from the seedlings of spring barley (Hordeum vulgare L. cv. Fatran) incubated at 40°C for 15 h was described.

In comparison with the parental cv. Finale the 'RisfixC' supernodulator exhibited higher, continuously increasing nodule number and fresh mass accumulation, but substantially lower individual nodule fresh mass, leghemoglobin concentration, and specific acetylene reduction activity of nodule tissue. There were no substantial differences between Finale and 'RisfixC' in total acetylene reduction, nodule leghemoglobin accumulation per nodulated root, total and specific CO₂ evolution from nodulated roots and gross CO₂ respiratory costs of acetylene reduction. The 'RisfixC' also exhibited a substantially lower plant dry mass production (by 30%), but nitrogen concentration in shoots and carotenoid concentration in leaf tissue were significantly higher by 33 and 14%, and the chlorophylla+b content insignficantly higher than in the parental cultivar. In contrast, the nodulation mutant 'Risnod29', exhibited a somewhat higher nodule fresh mass accumulation (by 21%) and individual nodule fresh mass (by 23%), total and specific acetylene reduction (by 49 and 19%) and a somewhat more rapid plant dry mass accumulation compared with the cv. Finale.

Plasma membrane H⁺ATPase extracted from leaves of spinach plants induced to flower by gibberellic acid treatments or by a transfer to a photoperiod of 24 h had a lower Km_app than that from vegetative plants grown in short days. The Km_app obtained after inhibition by vanadate was decreased in vegetative plants and increased in induced ones showing a differential effect of this inhibitor on the kinetic properties of the enzyme between vegetative and induced plants. The phospholipid fatty acid analysis of the purified plasma membrane showed an increase of C18:1/C18:2 fatty acid ratio upon induction by light or by gibberellic acid treatments, whereas the saturated to unsaturated fatty acid ratio was kept constant. The decrease in the Km_app observed after induction may be thus interpreted in terms of the observed changes in lipid environment.

Paclobutrazol, the gibberellin biosynthesis inhibitor, acceleratedin vitro tuber initiation of potato cv. Rema and increased the uniformity of tuberization period. However, the high concentrations (10-1000 mg l^-1) of this retardant, strongly decreased mass and/or number of microtubers. The microtubers were harvested and stored in darkness (22±2°C) for 250 d. After this period both sprouting and growth of sprouts were affected by previous paclobutrazol treatment.

Twenty-five visnagin sulfonamide derivatives were testedin vitro against sclerotial germination, growth and cellulolytic activity ofSclerotium cepivorum Berk. The effectiveness of the derivatives depends on the concentration and the substituent introduced to the title compounds. The introduction of SO₂Cl₂ to C₉ of visnagin induced high toxicity than introducing SO₂NH₂. Compounds with sulfonyl piperidine or sulfonyl morpholine gave small toxicity only at 30 and 75 μg cm^-3. Addition of N-aryl ring to visnagin-9-sulfonamide rendered the title compound to be more toxic. The substitution of the N-aryl ring bym-CH₃,m-Cl orp-Cl enhanced the toxicity, while its substitution witho-CH₃,p-CH₃,p-Br,o-OCH₃ orm-OCH₃ caused a drop in the toxicity as compared to compounds with unsubstituted aryl ring. Visnagin sulfonamide derivatives having azole rings were strongly inhibitory for sclerotial germination, growth, sclerotial formation and cellulolytic activity, even when applied at 4 μg cm^-3. The most toxic one was that having dimethyl isoxazole. The cleavage of γ-pyrone ring led to a decline in the toxicity as compared with the other sulfonamide derivatives.

Paraquat (methylviologen) at concentrations above 0.05 mM inhibited the growth of photoautotrophic cyanobacteriumGleeocapsa sp. in axenic cultures. The growth rate was not affected by concentrations of 0.01 mM or less. This concentration resulted after a lag period in a moderate increase in superoxide dismutase level. After removal of paraquat, the cyanobacterium continued to generate higher levels of superoxide dismutase. There was a lag period of one hour before resumption of normal enzyme activity. Addition of puromycin at concentration of 0.5 mg cm^-3 had no effect on cell survival, but greatly enhanced the sensitivity of the culture to the toxicity of paraquat. The data showed an increase of SOD activity by temperatures above the normal growth temperature level. However, this increase was suppressed by chloramphenicol which revealed that the induction of superoxide dismutase by high temperatures was associated withde novo protein synthesis.

C. rubrum plants of different age were treated with methyl jasmonate (JA-Me), in some cases in combination with photoperiodic flower induction. Plants treated with JA-Me (3×10^-4, 3×10^-5 and 5×10^-7M) showed inhibition of growth and flowering. No effect of JA-Me application on ethylene formation was observed.

The isoperoxidase and isopolyphenol oxidase patterns were studied in undifferentiated calli and regenerated shoots and roots of two cultivars ofActinidia deliciosa: one female cv. Hayward and one male cv. Matua. One characteristic, very stable isoperoxidase band (0.85<Rf<0.90) was found only in the male callus, shoots and roots cultured on media supplemented with zeatin (ZEA) or indole-3-butyric acid (IBA). In contrary, one isopolyphenol oxidase band (0.35<Rf<0.40) was typical for male callus and shoots cultured on the medium enriched with ZEA and another one (0.85<Rf<0.90) for male shoots and roots cultured on the medium with IBA. These specific bands had never been found in female cultivar.

Ten major host-encoded pathogenesis-associated proteins have been found in extracts of intercellular sap of cucumber cotyledons infected with tobacco necrosis virus. By native and two-dimensional SDS-polyacrylamide gel electrophoresis, five major acidic virus-elicited proteins have been identified and classified on the basis of their molecular mass in three groups: group 1 included one protein of 14 kD; group 2, one protein of 28 kD and group 3, three proteins of 37-40 kD. Another five viruselicited proteins were basis, and were again classified in three groups: group 1, included two proteins of 15-16 kD; group 2, two proteins of 22-23 kD; group 3, one protein of 40 kD.

Monogalactosyl diacylglycerol (MGDG), digalactosyl diacylglycerol (DGDG), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and sulfoquinovosyl diacylglycerol (SQDG) are the most abundant lipid classes present in both the autotrophically and heterotrophically grownChlamydomonas reinhardtii. However, phosphatidylcholine (PC) and diacylglycerol (N,N,N-trimethyl)-homoserine (DGTS) were absent in both alga types. The polyne index B was higher in heterotrophic than photoautotrophic algae, but the unsaturation index was higher in photoautotrophic algae PI, PE and DGDG. The proportion of linolenic acid decreased under heterotrophy with compensatory increases in hexadecadienoic (16 : 3), oleic (18 : 1) and linoleic (18 : 3) acids.

Increasing salinity of growth medium induced a reduction in growth and transpiration rate. The concentrations of chlorophylls and carotenoids were increased in most cases in broad bean leaves while in pea plants they remained more or less unchanged with the rise of salinization up to 80mM NaCl. Thereabove a significant decrease in these contents was observed. A stimulation of the net photosynthetic rate of pea was observed at the lowest levels of NaCl but at the highest levels inhibitory effect was recorded. In broad bean all salinization levels inhibited photosynthetic activity, but dark respiration of both plant species was stimulated. The content of Na⁺ in the roots and shoots of both species increased at increasing salinity. In broad bean, Ca²⁺ concentration in shoots and K⁺ and Ca²⁺ contents of roots increased at increasing salinization, while in pea plants, the content of K⁺ and Ca²⁺ was almost unaffected by salinity. Salinity induced an increase in the content of these ions in pea roots. Mg²⁺ content in shoots and roots of both broad bean and pea decreased at increasing salinity except in roots of pea, where it was generally increased.