One-year-old seeds of chickpea (Cicer arietinum L. cv. C-235) lost about 23 % germinability and leaked larger quantities of N, P, K, saccharides and proteins into the soaking medium in the first 48 h, as compared with fresh seeds. The protein content in stored seeds decreased more than in fresh seeds, as the soaking progressed.

The enzyme activities of the proline metabolic pathways were determined in control and satt-treated (140 M NaCl) calli derived from cotyledons of the domestic saltsensitive tomatoLycopersicon esculentum and the wild salt-tolerantL. pennellii. Glutamate, glutamine, asparagine, and aspartate levels increased in both genotypes under salt stress, while proline accumulation increased markedly only in the salt sensitive tomato. Activity of glutamine synthetase (GS) decreased in the salt-treated calli of the domestic species, whereas both NADH- and NADPH-glutamate synthase (GOGAT) activities increased; GS and NADPH-GOGAT decreased together in the salinized calli of the wild species. Decreasing ornithine levels were found due to NaCl in both tomato populations, while ornithine transaminase (OT) decreased in the wild type only. Increasing NADPH-Δ-pyrroline-5-carboxylate reductase (P5CR) and decreasing proline oxidase (Pro oxi) occurred in the salinized calli of the wild type. Conversely, Pro oxi and proline dehydrogenase (Pro dH) decreased highly in the salinized calli of the domestic population, while no significant changes in P5CR were found.

Gas exchange characteristics of a hemiparasiteMelampyrum arvense L. before and after attachment to the hostCapsella bursa pastoris (L.) Med. were compared. The net photosynthetic rates (P_N) on a leaf area basis were extremely low and in comparison to the value obtained for the host were about 15 % and 23 % for the unattached and attached hemiparasite, respectively. Also the concentration of photosynthetic pigments was low (as compared with the host the content of chlorophylls was about 33 % and 49 % and of carotenoids about 38 % and 36 % in the unattached and attached hemiparasite, respectively). On the other hand the rates of respiration were high (about 1.8 and 2.6 times higher in the unattached and attached hemiparasite, respectively, than in the host). In darkness stomatal conductance (g_S) of the host and the unattached hemiparasite was rapidly reduced to 10 % of the value obtained in light, g_S of the attached hemiparasite was decreased only by about 30%. A total reduction of g_S occurred at relative water content (RWC) of 85 %, 75% and 45 % for the unattached hemiparasite, the host, and the attached hemiparasite, respectively. The transpiration (E) rate in the preparasitic stage was very low, being 2.6 and 4.5 times smaller than in the host and the attached hemiparasite, respectively. In the attached hemiparasite WUE was 7.5 and 3 times poorer than in the host and in the preparasitic stage, respectively.

Wounding both cotyledons ofBidens pilosa (var.radiatus) induces the inhibition of hypocotyl growth. The wound signal is transmitted very rapidly from cotyledon to hypocotyl and can be visualized by the change in nucleotide pools. First we have shown that the irradiance of the plant can change the ATP level without plant wounding. Therefore, plants were harvested at the start of the light period. Under these conditions, we have determined in hypocotyl the levels of adenosine triphosphate (ATP), guanosine triphosphate (GTP) and non adenylic triphosphates (NTP), and adenylate energy charge (AEC) after wounding. We have observed a transient (2 min) increase in the ATP level followed by a decrease 5 to 30 min later. A similar result was obtained for the GTP level but with some delay. The GTP level increased in 5 min and then decreased after 60 min. For the NTP level the decrease is effective from 5 to 60 min after wounding. The calculation of AEC has shown that a very tight control in the level of ATP may be involved in response to wounding.

Changes in soluble protein profile and chlorophyll (Ch1) content in detached soybean leaves incubated in darkness or light were delayed by application of benzyladenine or indole-3-acetic acid and enhanced by abscisic acid. The degradation in light differed significantly from the degradation in darkness. Chl and proteins were lost at a higher rate in darkness than in light.

Suspension cultures of tomato cells were used to study the membrane injury by the toxic concentration of mercuric chloride. Assessment of electrolyte leakage, UV-absorbance of the tissue leachates, relative leakage ratio, injury index, membrane lipid peroxidation, lipoxygenase activity, α-amino nitrogen and total soluble carbohydrate contents showed the extent of membrane damage as a function of the increasing concentration of mercuric chloride. It is suggested that the selected parameters can be used as qualitative tests for determination of stress-induced membrane damage

Changes in the number of protoplasts, viability, protein and chlorophyll content were studied in tobacco mesophyll protoplasts cultivated either autotrophically in CPW medium with mannitol (MCPW) in the light or heterotrophically in CPW medium with glucose (GCPW) in the dark. The number and viability of protoplasts in the both cultivation media were unchanged. In MCPW in the light, the protein and chlorophyll content strongly decreased already after 12 h of cultivation, at 72 h of cultivation, values dropped to 23.6 % (proteins) and to 3.5 % (chlorophyll) in comparison with the initial content. In GCPW in the dark, the protein and chlorophyll contents decreased only slightly to 75 % (proteins) and to 57.7 % (chlorophyll).

In seedlings of the tropical tree speciesErythrina variegata Lam. andHardwickia binata Roxb. exposed to different acidic mist (H₂SO₄, pH 5, 3 and 2) for 5 d significant reduction in seedling growth, biomass accumulation and¹⁴CO₂ fixation were determined. In isolated chloroplasts a decrease in the activities of photosystem 2 and whole electron transport chain was observed only at pH 3 and 2, but no significant change in photosystem 1 activity was observed. SDS-PAGE analysis of crude leaf extracts of ribulose 1,5-bisphosphate carboxylase (RuBPC) indicated a significant loss of 55 and 15 kDa polypeptides at pH 2 inErythrina. The reduction in the RuBPC activity in seedlings grown under acidic mists correlated well with CO₂ fixation.

The influence of macronutrients and growth regulators on in vitro shoot proliferation and rooting of an East Spanish population ofMyrtus communis L. were studied. Preincubation of field material on a medium without mineral salts prevented the browning from phenolic exudates. For multiplication, nodal segments of 5 mm fromin vitro produced shoots were cultured on Murashige and Skoog (MS), Schenk and Hildebrandt (SH) and Heller (H) media (full strength or diluted to 1/2 or 1/4), with 6-benzylaminopurine (BAP) at concentrations 4.4, 13.3 and 22.2 ΜM or kinetin (K) at concentrations 4.7, 14.0 and 23.2 ΜM. The optimum shoot proliferation was on quarter-strength MS medium with 4.4 ΜM BAP, whereas the maximum number of nodal segments was produced on half-strength MS medium with 4.4 ΜM BAP. Rooting of shoots was obtained by adding 2.5 - 24.6 ΜM indole-3-butyric acid (IBA) and broad range of macronutrients; Lloyd and McCown (WPM) and Gresshoff and Doy (GD) media both full strength or diluted to 1/2 were optimum. No rooting was obtained in the presence of α-naphthaleneacetic acid (NAA).

Plants of two wheat (Triticum aestivum L.) cultivars differing in salt tolerance were grown in sand with nutrient solutions. 35-d-old plants were subjected to 5 levels of salinity created by adding NaCl, CaCl₂ and Na₂SO₄. Growth reduction caused by salinity was accompanied by increased Na⁺ and Cl^- concentrations, Na⁺/K⁺ ratio, and decreased concentration of K⁺. The salt tolerant cv. Kharchia 65 showed better ionic regulation. Salinity up to 15.7 dS m^-1 induced increased uptake of Na⁺ and Cl^- but higher levels of salinity were not accompanied by further increase in uptake of these ions. Observed increases in Na⁺ and Cl^- concentrations at higher salinities seemed to be the consequence of reduction in growth. Uptake of K⁺ was decreased; more in salt sensitive cultivar. This was also accompanied by differences in its distribution.

The final biological effect of auxin depends both on free auxin levels and on auxin perception capacity.RolB transformedBeta vulgaris L. hairy roots provide a system for studying both factors. Highly purified plasma membrane fractions were prepared with aqueous two-phase partitioning. Individual hairy root clones were assessed for the binding activities of plasma membrane-bound auxin binding proteins and for their free intracellular indole-3-acetic acid levels. The presence of a high affinity auxin binding protein with a dissociation constant of 9.07 x 10^-7 M was detected in the plasma membrane fractions isolated from non-transformed seedling roots and the six clones ofrolB transformed hairy roots. However, the levels of specific IAA binding considerably varied among different hairy root clones and between transformed and non-transformed roots. The levels of the detectable polypeptide in immunoblotting with an antibody against maize 22-kD auxin binding protein subunit were in good agreement to the levels that were detected in auxin binding assays. Differences in the indole-3-acetic acid levels were found between transformed and non-transformed roots and also between different transformed hairy root clones. A negative correlation was observed between free intracellular IAA levels and its specific binding to the plasma membrane-bound auxin binding proteins. A latency study indicated that the binding site for auxin may be located on the exterior face of the plasma membrane

In date palm (Phoenix dactylifera L.) leaves, the main compounds of the phenolic pool were quercetin and isorhamnetin heterosides, (+)-catechin and (-)-epicatechin. Although previously observed only in date palm fruits, 5-caffeoylshikimic acid (dactylifric acid) and its positional isomers (3-caffeoylshikimic acid and 4-caffeoylshikimic acid) were detected also in the leaves and roots. Quantitative, but not qualitative, differences between cultivars resistant and susceptible toFusarium oxysporum f. sp.albedinis during growth period were observed

Buthionine sulfoximine (BSO) specifically inhibits γ-glutamylcysteine synthetase and decreases a cellular level of glutathione (GSH) in maize seedling roots. Exogenous GSH restores Zn-phytochelatins synthesis in BSO-treated maize plants.

A modification of the procedure of extraction of cell wall solution for enzymatic determination of ascorbic acid and its reduction level in the apoplast of leaf cells is proposed. The modification consists in infiltration of leaves with citric acid/sodium phosphate buffer, pH 3, instead of customarily used neutral solutions. In acidic media autooxidation of ascorbic acid is effectively suppressed, so that infiltration could be performed at laboratory temperatures. Using polyacrylamide gel electrophoresis and infiltration solutions of pH down to 1.5 it is shown, that at pH 3 the extracted fluid is not contaminated with intracellular substances if appropriate vacuum and centrifugation forces are used. The modification is shown to be more effective for leaves ofPhaseolus than for those ofSpinacia. In cell walls of mature leaves of these species the concentration of ascorbic acid was found to be around 1 mM, with reduction level up to 0.90. The role of ascorbic acid in cell walls as ozone scavenger is discussed

Wheat leaves(Triticum aestivum L. cv. San Agustin INTA) were detached at the moment they had reached maximum expansion, put in tubes containing water and left in darkness. Under these conditions, leaf protein content decreased mainly as consequence of an increased rate of breakdown. In the range of 0 to 72 h after detachment, western blot analysis of leaf protein extracts displayed both similar proportions of total protein and quality of ubiquitin conjugates. Northern blot analysis of leaf RNA extracts revealed a 1.6 kb ubiquitin mRNA transcript which increased 3.5-fold after 48 h of treatment. Thus wheat leaves maintain both their ability for the ubiquitination of proteins and the transcription of ubiquitin mRNA at stages of senescence in which rates of protein breakdown are increased. The results suggest that the ubiquitin-dependent proteolytic pathway contributes to leaf protein breakdown during senescence

Standardized laboratory techniques for the vegetative growth of the duckweedSpirodela polyrhiza (Lemnaceaé), and for formation as well as germination of their turions were described. Increasing photon fluence rates of blue or red light increased the yield of turions. A specific stimulating effect of blue light was demonstrated under autotrophic but not under mixotrophic conditions. Therefore the spectral composition of light is not important in mixotrophic formation of turions whereas in autotrophic formation light sources with a higher portion of blue light are recommended. Dark-grown (etiolated) turions showed accelerated germination and higher germination percentage in comparison with light-grown turions after induction by a single red light pulse. This difference was overcome in continuous red light by speeding up the germination response of light-grown turions. Use of Petri dishes (8 cm³ nutrient solution) instead of Erlenmeyer flasks (50 cm³ nutrient solution) retarded germination response. Especially for long term experiments the use of Erlenmeyer flasks is recommended. Storage of turions for 72 h at 25 ‡C following at 5 ‡C in darkness after-ripening resulted in a decreased lag phase of the light-induced germination both after induction by a single light pulse and in continuous light.

Phaseolus vulgaris L. seedlings were grown under different air humidities simulating conditions during micropropagation (very high humidity duringin vitro cultivation and low air humidity after transferex vitro). The functional stomatal apparatus developed after a short period of growth at low air humidity at the beginning of plant ontogeny or after transfer from high to low air humidity, but not in plants grown steadily under high air humidity. The ability of stomata to regulate gas exchange was not persistent and disappeared after transfer of plants from low to high humidity.

Qualitative and quantitative differences in cytokinin levels of gram seeds were observed during germination of control and 6-benzylaminopurine (BAP; 4.44 x 10^t-5 M) treated seeds. Zeatin riboside (ZR), zeatin (Z), dihydrozeatin (DHZ), isopentenyladenosine (iPA) and isopentenyladenine (iP) were determined using high pressure liquid chromatography. In the control seeds the ZR content increased markedly only after 24 h of germination. In BAP treated seeds, the increase in ZR content was stronger than in control seeds and it persisted during further germination. Z content increased during germination in both control and treated seeds. After 48 h of germination iP appeared in control and especially in treated seeds.

Maize (Zea mays L. cv. Ganga-5) seedlings were grown in the presence of ferulic acid (0.5 - 3.0 mM) for 8 d. Treatment with ferulic acid considerably decreased shoot and root length, increased the activity of peroxidase, catalase and indole-3-acetic acid (IAA) oxidase and decreased the activity of polyphenol oxidase. The increased activity of peroxidase correlated with pronounced increase in content of lignin and phenolic compounds

In two selected nitrogen-fixing cyanobacterial speciesAnabaena fertilissima andAnabaena variabilis pH, irradiance and different inocula sizes considerably modified the toxic effect of 50 % effective concentration (EC 50) dose of the pesticideFuradan (carbofuran 75 DB). Maximum growth and chlorophyll (Chl)a content ofA. fertilissima was observed in the pH range of 8 - 9 and that ofA. variabilis at pH 7-8, while at acidic pH (5 - 6) and at pH above 9 these parameters were considerably retarded. Toxicity of the EC 50 dose ofFuradan was increased further at pH 5-6, whereas reduction in the toxicity to the test cyanobacteria was observed at pH 7.8 - 9.0. The experimental organisms grew comparatively better and synthesized higher amount of Chl a at an irradiance of 12.5 than at 7.5 or 2.5 W m^-2. The toxicity of EC 50 dose of the pesticide gradually decreased with the increasing irradiance. The toxic effect ofFuradan was larger when the initial cyanobacterial population concentration was low andvice versa.

Potato virus A (PVA) was treated with different glutaraldehyde concentrations at a range of different pH values, and its immunochemical reactivity and integrity was tested in various types of ELISA using a panel of six monoclonal antibodies. Glutaraldehyde fixation was compared with formaldehyde fixation, and there was no significant difference in reactivity between PVA non-treated and treated with formaldehyde, but almost the entire immunochemical activity was lost after treating with glutaraldehyde.

The effects of kinetin (Kn) on pigment content and electron transport activities (ETA) in wheat leavesin vivo and chloroplastsin vitro aging in light was investigated. Excised wheat leaves were infiltrated with Kn for 3 h under irradiation. The treatment increased zeaxanthin (Zx) content by 40% and also increased chlorophyll (Chia, Chib) and major carotenoid (Car) contents in the leaves (per fresh mass unit). Chloroplasts isolated from Kn treated leaves, when incubated in light for 4 h showed relatively lower pigment loss and slower loss of ETA compared to the chloroplasts of untreated leaves. These observations suggest photoprotective action of Kn. The photoprotection was more prominent when Kn was applied directly to the irradiated chloroplastsin vitro. Moreover, chloroplasts agingin vitro under irradiation without Kn treatment lost pigments and ETA. Within 3 h of irradiation, both whole chain (H₂O to methylviologen) electron transport as well as photosystem (PS) 2 activity were completely lost. However, in the chloroplasts treated with Kn, the loss of pigments was slow and even after 4 h of irradiation the chloroplasts retained 15 % of PS 2 and 9 % of whole chain ETA. In the untreated chloroplasts, the loss of Zx after 4 h of irradiation was 49 % whereas in Kn treated samples its level was 1.3 times higher than that of control. Since a higher level of Zx was maintained in Kn treated chloroplasts, photoprotective action of Kn is possibly mediated through Zx.