The seasonal dynamics in content and distribution of N-rich compounds between overwintering organs of Calamagrostis epigeios were examined. Samples were taken both from plants grown in natural conditions and in containers with controlled nutrient supply. There were significant changes in content of nitrate, free amino acids and soluble protein in all investigated plant parts during the course of a year. Amino acids showed both the highest maximum and seasonal fluctuation among the all N compounds observed and, therefore, appear to have a central role in N storage. Their content rises in the autumn, remains stable during winter and declines quickly at the beginning of spring. The most abundant amino acids in the end of winter storage period - asparagine, arginine and glutamine - constituted about 90 % of N in fraction of free amino acids. The portion of N stored in soluble proteins, however, was considerably smaller compare to both amino acids and nitrate. The amount of N stored in rhizomes of C. epigeios was smaller than in roots and stubble base before the onset of spring re-growth. This indicates that roots and stubble base are particularly important for winter N storage in this species.

Vigna radiata (L.) seedlings (5-d-old) were exposed to different concentrations of NaCl in light and in dark. The content of proline in the shoots increased with an increase in NaCl concentration, in light as well as in dark. But, irrespective of the concentration of NaCl, proline accumulation in the shoots was higher in light than in dark. Pretreatment of seedlings with dichlorophenyl dimethyl urea (DCMU) did not make any significant difference in light promoted stress induced proline accumulation. As DCMU is a potent inhibitor of photosynthetic electron transport, the light reaction of photosynthesis was not responsible for the observed light promotion of stress induced proline accumulation. In another set of experiments, 5-d-old green as well as etiolated seedlings were exposed to NaCl stress in the presence of different concentrations of sucrose. Irrespective of the concentration of sucrose used, proline content in shoots of stressed seedlings was higher in light than in dark. Although, sucrose enhanced NaCl stress induced increase in proline content in dark by about 32 %, this enhancement was not comparable to the 286 % increase in proline content brought about by light. These results showed that certain factors other than photosynthesis play a role in light promotion of stress induced proline accumulation.

Diurnal and seasonal changes of net photosynthetic rate (P_n) and the efficiency of photosystem 2 (F_v/F_m) were measured on two perennial species growing on a soil catena in semi-arid south-east Spain. Stipa tenacissima, a tussock grass, grows on shallow soil at the top of the catena and Retama sphaerocarpa, a leguminous shrub, grows in the valley bottom. A linear relationship was found between light saturated photosynthetic rates (P_max) and diffusive leaf conductance (g_l) in both Retama and Stipa indicating that the intercellular CO₂ concentration (c_i) was maintained constant in both species diurnally. Relatively high values of calculated c_i in Retama cladodes suggested that was not the primary limitation to carbon assimilation. F_v/F_m for the two species when well watered was around 0.8. Although Retama cladodes maintained this value throughout the year, F_v/F_m decreased to a minimum of 0.43 in Stipa leaves, at the end of the dry season. Our data suggest that plants in the Rambla Honda can substantially reduce transpiration without reducing photosynthetic rates to the same extent by closing their stomata, because P_n is reduced primarily by high respiration, decreased mesophyll conductance and by photoinhibition or permanent damage of photosystem 2.

Cell suspension culture of Eschscholtzia californica Cham. were permeabilized by Tween 20 or 80, and immobilized by glutaraldehyde. The highest invertase activity was at pH 4.5 and temperature 50 °C. The hydrolysis of the substrate was linear for 5 h reaching 60 % conversion. The cells had high invertase activity and a good stability, and in long-term storage they showed convenient physico-mechanical properties.

Treatment of spruce, fir and oak trees with herbicides, which may be one of the forest damage inducing agents, caused pronounced changes in the contents and distribution of indole-3-acetic acid (IAA) and cytokinins (CKs) one year after treatment, i.e. at the time of the first microscopically visible damage in treated trees. In Picea pungens IAA content increased in the terminal buds by about 105 % and in the apical buds of the first order branches by 220 %. The same was true for young sprouts of Abies nordmanniana, while in leaves of oak trees IAA content was decreased by 15 % after glyphosate treatment and by 30 % after 2,4-dichlorophenoxyacetic acid (2,4-D) treatment. Another striking feature was a significantly decreased content of IAA in the lower parts of roots in Picea pungens (50 % of the control), which is accompanied by an increase in IAA content in the middle part of the roots (130 %). On the other hand, the IAA content of both sprouts and roots of A. nordmanniana was significantly increased after herbicide treatment.
In P. pungens, the content of free cytokinins (sum of zeatin, zeatin riboside, isopentenyladenine and isopentenyladenosine) decreased due to herbicide treatment. The strongest decrease was seen in roots, especially in their upper and middle parts (the average reduction of cytokinin content in roots was 63 %). In the above-ground organs the reduction was seen namely for isopentenyladenine and isopentenyladenosine, while the abundance of zeatin riboside was, on the other hand, higher in treated plants. In Quercus robur leaves, the total content of cytokinins also decreased, namely after glyphosate treatment. In consequence of these changes, CK/IAA ratio decreased pronouncedly in all organs of herbicide-treated trees, with the exception of oak leaves treated by 2,4-D.

Treatment of Taxus chinensis cell suspension cultures with fungal elicitor resulted in an oxidative stress characterized by H₂O₂ production, malondiadehyde (MDA) accumulation and cell death. This oxidative stress was dependent on the concentration of elicitor. Cells exposed to elicitor accumulated taxol, however, not proportional to elicitor concentration. High production of taxol occurred in cells treated with the suitable elicitor concentration. We concluded that oxidative stress had the deleterious effect on taxol production. Simultaneous treatment with elicitor and ascorbic acid (ASA) changed the oxidative stress and taxol production. Production of taxol in cells treated with 200 mg dm^-3 elicitor and ASA was enhanced compared with that in cells treated with only 200 mg dm^-3 elicitor, while production of taxol in cells treated with 100 and 50 mg dm^-3 elicitor and ASA was decreased compared with that in cells treated with 100 and 50 mg dm^-3 elicitor.

Ornithine carbamoyltransferase (OCT) from spinach (Spinacea oleracea L.) was purified to homogeneity and studied for some kinetic and structural properties. The enzyme showed a specific activity of 436 U mg^-1, its molecular mass was approximately 118 kDa as estimated by Sephacryl S-200 gel filtration chromatography, the purified protein ran as a single band of 38 kDa in sodium dodecyl sulfate-polyacryamide gel electrophoresis. The enzyme catalyses an ordered bi-bi-sequential reaction in which carbamoyl phosphate binds first, followed by L-ornithine; L-citrulline leaves first, followed by phosphate. The Michaelis constant was 0.19 mM for L-ornithine and 13.1 µM for carbamoyl phosphate; the dissociation constant for the enzyme and carbamoyl phosphate complex was of 19 µM. The K_m of the reaction decreases from pH 6.0 to pH 10.4. The enzyme is heat-labile, but it was protected from thermal inactivation by substrates; more by ornithine alone than by two substrates acting together.

This study investigated the influence of osmotic stress, induced by sorbitol and sucrose combinations, on growth and proline accumulation in callus cultures of rice (Oryza sativa L.). Dehusked mature seeds, cv. Hassawi, were induced to callus on MS medium supplemented with 4.52 µM 2,4-dichlorophenoxyacetic acid (2,4-D) and 2.32 µM 6-furfurylaminopurine (kinetin). The medium also contained 29.2, 58.4, 87.6, and 116.8 mM sucrose combined with 0, 54.9, 109.8, and 164.7 mM sorbitol. Callus formation was observed in about 35 % of the cultured seeds irrespective of the sugar treatment. An increase in callus mass was observed as sucrose concentration increased reaching a maximum growth at 87.6 mM. Callus growth was enhanced in response to 54.9 mM sorbitol but at higher concentration it was inhibitory. Best callus growth was obtained on a medium containing 54.9 mM sorbitol combined with 87.6 mM sucrose. Increasing osmotic stress, as a consequence of increasing sucrose and sorbitol concentrations, induced proline accumulation and the highest concentration of proline, 5.8 µmol g^-1(f.m.), was obtained on 164.7 mM sorbitol combined with 116.8 mM sucrose.

A reliable method for the long-term conservation of date palm tissue cultures is described. In vitro shoot bud and callus culture were successfully stored for 12 months at 5°C in the dark. At this conditions high percent of cultures remained viable without serious signs of senescence. However, the growth rate decreased as storage period increased. The role of sorbitol as osmotic agent in storage was examined. Health shoot bud cultures were obtained after 6 months of storage on medium containing 40 g dm^-3 sorbitol. This period extended for 9 months in case of callus cultures.

Four physiologically and phenotypically diversified tobacco (Nicotiana tabacum L. cv. Samsun) plantlet variants had been generated by cultivation on media either lacking or containing sucrose (0 and 3 %, m/v) under two different photon flux densities (PFD), 50 µmol m^-2 s^-1 (LL) and 200 µmol m^-2 s^-1 (HL). Plantlets were transferred into soil without any pre-acclimation and grown either under PFD of 200 µmol m^-2 s^-1 or 700 µmol m^-2 s^-1. Sucrose feeding in vitro resulted in reduced degree and duration of wilting after transfer. The highest readiness for ex vitro acclimation was found in 3 % HL plants, in which changes of photosynthetic apparatus and stress responses were the smallest. On the contrary, the steepest decline of Fv/Fm ratio on the first day after transplantation, doubled chlorophyll content and almost tripled D1/LHC 2 ratio after 7 d of ex vitro growth under 700 µmol m^-2 s^-1 characterized 0 % HL plants, which had suffered chronic photoinhibition in vitro. Remarkably high abscisic acid content at the end of in vitro cultivation and during acclimation as well as increased synthesis of both D1 and LHC 2 proteins even at the end of analyzed acclimation period were found only in 0 % LL plants. Increase of D1/LHC 2 ratio and chlorophyll contents demonstrate that in vitro developed leaves of all plant variants are able to acclimate to new environment. The most surprising result in the whole study is the drop of D1 protein synthesis in all plants on the 3^rd day. Five times decline of photoprotection level of xanthophylls in plants after ex vitro transfer into the same PFD showed stress character of in vitro cultures.

The effect of two elicitor types prepared from three different fungi on the alizarin content and the ultrastructure of Rubia tinctorum cells was studied. The de novo alizarin synthesis took place predominantly during the first day of treatment then it was followed by a constant release of alizarin into the medium. The alkalinization of the medium was similar in every treatment. The number of the living cells did not changed during 24-h elicitor treatments, but it decreased significantly after 96 h. The appearance of vacuolar bodies, and the change of the plasmalemmasome structure from vesiculo-reticular to reticulo-lamellar were the most typical morphological syndromes due to elicitation. Phytium elicitor proved to be the least effective, and Botrytis elicitor seemed to be the most effective.

Dog rose (Rosa canina L.) plants in the bloom stages of flowering were sprayed by indole-3-acetic acid (IAA) in concentrations of 0.06 and 0.60 mM and gibberellic acid (GA₃) in concentrations of 0.60 and 1.50 mM. Ascorbic acid, total sugar, reducing sugar and carotenoid contents gradually increased, while the protein content remained unchanged and the content of phenolic substances decreased during hypanthium development. Ascorbic acid, total sugar, reducing sugar and carotenoid contents increased in hypanthium sprayed by GA₃ and IAA. However, IAA and GA₃ applications (except low concentrations) decreased contents of phenolic substances. IAA and GA applications might be a good way to produce the high quality hypanthium in R. canina.

Multiple shoot regeneration from the cut plumular ends of embryo axes of chickpea (Cicer arietinum L.) was evaluated on Murashige and Skoog medium having different concentrations of thidiazuron (TDZ) (0.1 to 10.0 mg dm^-3) 6-benzylaminopurine (BAP) (0.5 and 1.0 mg dm^-3), kinetin (0.5 and 1.0 mg dm^-3) or zeatin (2.0 and 4.0 mg dm^-3). TDZ (0.2 mg dm^-3) was found to be the most effective cytokinin as it produced multiple shoots in 100 % of the explants from genotypes C235, ICC5166, ICC12269, ICC4951, ICC11531, BG256 and a local cultivar. Shoots were elongated on growth regulator-free medium, and rooted on growth regulator-free medium containing 1/4 MS salts + full vitamins + 3 % sucrose. Plantlets formed were acclimatized for 12 - 15 d in MS medium with a gradual reduction in sucrose concentration and transferred into pots filled with soil and kept in the field; this resulted in more than 70 % survival. The plants developed normally and produced fertile flowers and set seeds. Low temperatures, maximum 19.0 °C, and minimum 8.2 °C, during the first 15 d of transfer favoured survival on transfer to pots.

Salinity induced changes in α-amylase activity in three cotton cultivars (NIAB-Karishma, NIAB-86 and K-115) was studied during germination and early seedling growth under controlled conditions. The increase in NaCl concentration resulted in the decrease in α-amylase activity and break down of starch into reducing and non-reducing sugars in all cultivars, however, it was more pronounced in NIAB-86. K-115 showed highest germination followed by NIAB-Karishma and NIAB-86.

Sugar cane (Saccharum officinarum L. cv. Copersucar SP80-3280) seedlings were grown in nutrient solution with varying concentrations (0, 2 and 5 mM) of cadmium chloride for 96 h. Leaves were analysed for catalase (CAT), glutathione reductase (GR) and superoxide dismutase (SOD) activities. Although a clear effect of CdCl₂ on plant growth was observed, the activity of SOD was not altered significantly. However, the CAT activity decreased as the concentration of CdCl₂ increased. GR exhibits a significant increase in activity at 2 and 5 mM CdCl₂. CAT and SOD isoenzymes were further characterised by analysis in non-denaturing PAGE. Activity staining for SOD revealed up to seven isoenzymes in untreated control and 2 mM CdCl₂ treated plants, corresponding to Cu/Zn-SOD isoenzymes. At 5 mM CdCl₂, only six Cu/Zn-SOD isoenzymes were observed. No Fe-SOD and Mn-SOD isoenzymes were detected. For CAT, one band of activity was observed.

Vegetative fragments of the subtidal macroalga Gracilaria edulis (Gmel.) Silva cultured under field conditions at Thonithurai were subjected in the laboratory to UV-B radiation (280 - 320 nm). UV-B inhibited the accumulation of chlorophyll and phycobiliproteins, and lowered agar yield (23 to 43%) and its gel strength (22 to 36%) under 12 to 72 h exposure. The longer the exposure to UV-B radiation the more significant impact on pigments and phycocolloid properties of Gracilaria edulis was observed.

Using the whole plant and model systems, we demonstrate that the aluminum ions (Al³⁺) stimulate phenolic-dependent lipid peroxidation. Lipid peroxidation in barley (Hordeum vulgare L. cv. Donor) roots was 30 % higher under AlCl₃ treatment than without Al. Major decomposition product of lipid peroxidation was 4-hydroxynonenal (4-HNE) but not thiobarbituric acid reactive substances (TBARS), a widely used markers for lipid peroxidation. Similarly, AlCl₃ stimulated lipid peroxidation of soybean liposomes in the presence of chlorogenic acid (CGA) and H₂O₂/horseradish peroxidase system which can oxidize phenolics. Al³⁺ was found to enhance lipid peroxidation induced by oxidized CGA. Intermediates of lignin biosynthesis in plants, including p-coumaric acid, ferulic acid, sinapic acid and coniferyl alcohol, also showed similar effects. These results suggest that Al³⁺ has a potential to induce oxidative stress in plants by stimulating the prooxidant nature of endogenous phenolic compounds.

An integrated approach has been developed for targeted retrieval of microsatellite markers from selected regions of the field bean (Vicia faba L.) genome. The procedure is based on a combination of advanced physical and genetic mapping techniques and includes the following steps: 1) flow-sorting of metaphase chromosomes, 2) construction of microsatellite-enriched chromosome-specific DNA libraries, 3) isolation of polymorphic microsatellite sequences from the libraries, 4) testing chromosome specificity of the microsatellites using polymerase chain reaction with purified fractions of individual chromosome types, and 5) integration of chromosome-specific markers into a genetic map. Several strategies for isolation of microsatellite clones were tested, including direct screening of non-enriched libraries with single or mixed probes and screening of the libraries after one or two rounds of enrichment. Finally, the usefulness of this approach was demonstrated by the retrieval of novel markers from a selected portion of the largest field been chromosome (No. 1).

Response of two spring wheat (Triticum aestivum L.) cultivars, salt tolerant SARC-I and salt sensitive Potohar, to different concentrations of NaCl was examined under glasshouse conditions. Eighteen-day-old plants of both the lines grown in sand culture were irrigated with 0 (control), 80, 160 or 240 mM NaCl in full strength Hoagland's nutrient solution. Shoot fresh and dry masses, and leaf area per plant of SARC-I at the vegetative stage, were significantly greater than those of cv. Potohar at higher salt concentrations, however, relative growth rate (RGR) of cv. Potohar was significantly higher than that of SARC-I. SARC-I had higher net photosynthetic rate (P_N), stomatal conductance (g_s) and transpiration rate (E) than cv. Potohar at the vegetative stage, but the cultivars did not differ significantly in water-use efficiency (P_N/E), intrinsic water use efficiency (P_N/g_s), and intercellular/ambient CO₂ concentration ratio. At the grain development stage, SARC-I had significantly higher P_N and g_s in the flag leaf than cv. Potohar under salinity. SARC-I was superior to cv. Potohar with respect to number of grains per spike, number of grains per spikelet, mean grain mass, and grain yield per plant at all NaCl concentrations.

Plants subjected to stress show accumulation of proline and other amino acids. The role played by accumulated amino acids in plants varies from acting as osmolyte, regulation of ion transport, modulating stomatal opening, and detoxification of heavy metals. Amino acids also affect synthesis and activity of some enzymes, gene expression, and redox-homeostasis. These roles played by amino acids have been critically examined and reviewed.

Ammonium ion accumulation in detached rice leaves treated with phosphinothricin (PPT), an inhibitior of glutamine synthetase (GS), was investigated in the light and darkness. PPT treatment increased NH₄⁺ content and induced toxicity in rice leaves in the light but not in darkness, suggesting the importance of light in PPT-induced NH₄⁺ toxicity in detached rice leaves. PPT treatment in the light resulted in a decrease of activities of the cytosolic form of GS and the chloroplastic form of GS. The photosynthetic electron transport inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea reduced NH₄⁺ accumulation induced by PPT in the light. In darkness, PPT-induced NH₄⁺ accumulation and toxicity were observed in the presence of glucose or sucrose.

The effects of NaCl on putrescine (Put) content and diamine oxidase (DAO) activity in roots of rice seedlings were examined. NaCl treatment lowered the content of Put and increased the activity of DAO in roots. Our current results indicate that Cl^- is not required for NaCl-induced decline in Put content and increase in DAO activity in roots. Put content in roots of rice seedlings exposed to NaCl is possibly regulated by DAO activity.