In conifers, relationship between ethylene and the response to inclination are not well understood. The aim of this work was to study the consequence for the application of 2-chloroethyl phosphonic acid (ethephon), compound able to release ethylene, in one-year-old Pinus radiata D. Don seedlings subjected to inclination. In plants exposed to inclination for 15 d, increase in thickness of cell walls, more rounded shape of xylem cells, and accumulation of lignin were observed. Ethephon application accelerated significantly these changes; they can be observed after 5 d of inclination. The quantitative polymerase chain reaction (qPCR) showed up-regulation of transcripts from genes encoding phenylalanine ammonia lyase and cinnamyl alcohol dehydrogenase after inclination and their possible ethylene signal-dependence. As conclusion, morphological changes on stem xylem cells in young seedlings of radiata pine exposed to inclination are similar to those observed in compression wood and they are influenced by ethephon application.

Treatment of potato (Solanum tuberosum) plants with cadmium or abscisic acid (ABA) enhanced the content of StPCS 1 transcript and activity of phytochelatin synthase (PCS) in roots.transcript and activity of phytochelatin synthase (PCS) in roots. These treatments enhanced the contents of ABA and expression of genes coding 9-cis-epoxycarotenoid dioxygenase 1 (NCED1) and basic leucine zipper (b-ZIP).expression of genes coding 9-cis-epoxycarotenoid dioxygenase 1 (NCED1) and basic leucine zipper (b-ZIP). Simultaneous treatment of potato plants with Cd and fluridone (Flu), an inhibitor of ABA biosynthesis, completely halted the Cd-induced transcription of StPCS1, NCED1 and StbZIP genes and limited the increases in PCS activity and ABA content. The data suggest that ABA participates in transduction of the Cd signal to the cells of potato roots.

Gynogenesis of Chinese long cucumber (Cucumis sativus L.) was obtained from unpollinated ovules cultured on cucumber basal medium (CBM) supplemented with thidiazuron (TDZ) and in some experiments AgNO₃. High induction frequencies (7.85-12.14 %) were induced from unpollinated ovules at the time of anthesis at 0.03-0.07 mg dm^-3 TDZ. Histological analysis indicated that embryo sacs developed completely at the time of anthesis. Further, the highest plant regeneration rate was achieved at CBM supplemented with 0.05 mg dm^-3 a-naphthaleneacetic acid, 0.2 mg dm^-3 6-benzyladenine and 5-10 mg dm^-3 AgNO₃. Flow cytometry analysis showed that 80 % of the regenerated plants were haploid. Histological micrographs and ploidy level analyses clearly revealed initiation, development, and germination of embryos from the unpollinated ovules.

The protein elicitor cerato-platanin (CP) is known to induce defence-related responses in various plants. Some of these responses occur very quickly. In the present work, transcriptional changes caused by CP in leaves from Platanus × acerifolia (Aiton) Willd. were studied. With a cDNA microarray, 131 differentially regulated transcripts were identified as responsive to CP after 24 h of treatment. Eighty-six of these were cold-or ozone-modulated transcripts, thus revealing a significant overlap between genes responsive to CP and to cold/ozone stress. The transcriptional changes caused by CP were compared with the CP-orthologous protein Pop1 in a time-course analysis performed after 3, 6, 12, and 24 h of treatment by real-time RT-PCR on five defence-related genes. Despite some differences, CP and Pop1 were both able to induce early transcriptional changes (WRKY was overexpressed after only 3 h) confirming that pathogenassociated molecular patterns (PAMPs) act very quickly on gene transcription.

Programmed cell death (PCD) is a genetically controlled and conserved process in eukaryotes during development as well as in response to pathogens and other stresses. BAX inhibitor-1 (BI-1) has been implicated as an anti-PCD factor which is highly conserved in plants. Sequence of putative cucumber BI-1 protein exhibited 77.7 % identity and 91.2 % positive value with the homologue Blast BI-1 protein of Arabidopsis thaliana (AtBI-1). This highly homologous protein to the AtBI-1 protein was named CsBI-1. This protein contains an open reading frame (ORF) of 250 amino acids with a BAX inhibitor domain and five transmembrane regions conserved among members of the BI-1 family. Primers designed by the cDNA of CsBI-1gene were used for further sequencing. Cell death in cold-stored cucumber developed concomitantly with increased expression of the CsBI-1 gene and reached maximum at day 6. However, cell death accelerated significantly after 9 d when sharp decrease of the CsBI-1 expression occurred. After warming to 20 °C, expression of the CsBI-1 gene was the highest at day 3, decreased afterwards, and the lowest expression was detected at day 9 when PCD obviously appeared. The overall results indicate that CsBI-1 is cucumber homologue of Arabidopsis thaliana AtBI-1 gene. CsBI-1 is a conserved cell death suppressor induced by cold stress and a negative regulator of PCD.

We investigated the role of 24-epibrassinolide (EBR) in the amelioration of phenanthrene (PHE) stress in tomato (Solanum lycopersicum L.). Exposure to PHE (300 μM) significantly decreased shoot and root length (19 and 16 %, respectively), fresh mass (35 and 43 %, respectively), contents of chlorophyll a (26 %), chlorophyll b (27 %) and carotenoids (18 %) in tomato plants. In addition, PHE increased the malondialdehyde (MDA) content (57 %) and activity of secondary metabolism related enzymes glutathione-S-transferase (GST), glucose-6-phosphate dehydrogenase (G6PDH), shikimate dehydrogenase (SKDH), phenylalanine ammonia-lyase (PAL) and cinnamyl alcohol dehydrogenase (CAD). The expression levels of GST1, PPO, SKDH, PAL and CAD genes were also induced by PHE. Importantly, EBR (0.1 μM) alone and in combination with PHE increased the growth, biomass and activity of those enzymes significantly over control and PHE alone, respectively. Consistent with enzymes activities transcript levels of GST1, PPO, SKDH, PAL and CAD were further increased in PHE+EBR over PHE alone. However, MDA content was remarkably decreased in PHE+EBR than PHE alone. Meanwhile, content of phenols, flavonoids and antioxidant activity were increased by PHE and PHE+EBR further increased all those parameters. These observations suggest that EBR regulates secondary metabolism in tomato which might enhance tolerance to PHE.

Daucus carota is cultivated widely but grows best in cool climates. Suppression subtractive hybridization (SSH) is a PCR based method used to selectively amplify differentially expressed cDNAs and simultaneously suppress non-target cDNA. A subtraction forward library was constructed using RNA isolated from the leaves of unstressed and cold stressed carrot plants to determine the genes upregulated during cold stress. Out of the hundreds of clones obtained, sequences of 41 promising clones were submitted to the NCBI EST database. Sequence analyses revealed that these genes have significant roles in signal transduction, osmolyte synthesis and transport, regulation of transcription, translation and protein folding. Semiquantitative real-time polymerase chain reaction analysis (sqRT-PCR) of Dc cyclin, Dc WD and Dc profilin shows that the first two genes were upregulated while Dc profilin was constitutively expressed, but the analyses of the same with SSH, a much more sensitive technique showed an upregulation of all three genes.

Sex-related differences in the responses of plants to CO₂ enrichment are still rarely studied. In this study, we examined the effects of elevated atmospheric CO₂ (720 μmol mol^-1) on the activities of polyphenoloxidases (PPOs) and guaiacol peroxidases (PODs) in male and female plants of two ecologically divergent willow species Salix repens and S. phylicifolia. We detected that females invested more in PPO-based defence than did males, whose PPO activity decreased as a result of CO₂ enrichment. Moreover, we found that the inherently slow-growing S. repens had markedly higher POD activity than did the more rapid-growing S. phylicifolia. The PODs of these two species also differed in their biochemical properties.

The relationship between somatic embryogenesis (SE) and the expression of the BABY BOOM (BBM) gene was studied in cultured immature zygotic embryos (IZEs) using a transgenic line of Arabidopsis thaliana containing a BBMPro::GUS construct. Results showed spatio-temporal differences in BBM expression in explants during culture. BBM promoter activity was observed in freshly isolated IZEs except distal parts of cotyledons. At the beginning of culture, considerable increase of GUS staining intensity was observed in all parts of explants, which maintained at high level over next few days and coincide with cell divisions. Gradual decrease of GUS distribution in explants was observed at about the 5th day of culture. BBM promoter activity became largely restricted to dividing cells, then to developing somatic embryos, shoot-like structures and callus. In parts of explants not involved in morphogenesis BBM promoter activity was absent or hardly seen. Thus the in vitro expression of BBM coincides with cell proliferation and morphogenesis.

The effects of lead were investigated in bean plants (Phaseolus vulgaris L. cv. Zlota Saxa) grown hydroponically in nutrient solution and exposed to Pb(NO₃)₂ (0.1, 0.5, 1 mM) with or without equimolar concentrations of chelator ethylenediaminetetraacetic acid (EDTA). The roots treated only with Pb(NO₃)₂ accumulated up to 25 g(Pb) kg^-1(d.m.), during 4-d exposure. However, in bean plants exposed to 0.5 mM Pb + 0.5 mM EDTA or 1 mM Pb + 1 mM EDTA 2.5 times less Pb was determined. In bean plants treated only with Pb, less than 6 % of total lead accumulated was transported to the aboveground parts, while in the case of plants grown with Pb + EDTA, around 50 % of total Pb was transported to the shoots.

An AREB gene, designated as AhAREB1, was cloned from peanut (Arachis hypogaea L.). The gene contains a 1 338-bp open reading frame that encodes a putative protein of 445 amino acids. The corresponding genomic DNA containing four exons and three introns was isolated and analyzed. An upstream 1 060-bp DNA promoter fragment of the AhAREB1 gene was also amplified from peanut genomic DNA. Multiple sequence alignment of the deduced amino acids of AREB showed that the AhAREB1 protein shares high sequence homology with GmAREB1, S1AREB and ABF2. Quantitative real-time PCR analysis showed that AhAREB1 was induced by polyethylene glycol, NaCl, gibberellic acid, abscisic acid and salicylic acid. The cloning and characterization of the AhAREB1 gene will be useful for further studies establishing the biological role of AhAREB1 in plants.

Lithium pollution may seriously influence the metabolic and signalling processes of plants. In the present paper, we investigate the effect of lithium chloride on fungal elicitor-triggered H₂O₂ generation in Rubia tinctorum L. cell cultures. Our results show that Li⁺ strongly influences elicitor-induced H₂O₂ formation and time-course in the cells nad culture medium. Neomycin, a phospholipase C inhibitor, and 2-APB, an inositol-1,4,5-triphosphate (IP₃) receptormediated Ca²⁺ release blocker, strongly affected the elicitor-induced H₂O₂ production and had a similar effect on elicitor-triggered H₂O₂ formation as Li⁺. We monitored changes in H₂O₂ location at subcellular level and our observations confirmed the changes measured by quantitative methods. The obtained results enabled us to deduce that the IP₃ pathway might be involved in the early signalling events leading to the moderation of elicitor-induced reactive oxygen species generation.

To examine whether ferulic acid (FA) could protect plants from dehydration stress and to investigate a mechanism for the protection, cucumber seedlings were pretreated with 0.5 mM FA for 2 d and then were exposed to dehydration induced by 10 % polyethylene glycol 6000. After pretreatment with FA, the activities of antioxidant enzymes (catalase, superoxide dismutase, and quaiacol peroxidase) in leaves were higher than under dehydration treatment alone which was in accordance with the increased transcript levels of respective genes. Moreover, the combination of FA pretreatment and dehydration reduced the content of superoxide radical, hydrogen peroxide, and malondialdehyde, and increased the relative water content and content of FA, proline, and soluble sugars in comparison with dehydration alone. We propose that pretreatment with FA protects cucumbers against dehydration stress by decrease of lipid peroxidation due to activation of antioxidant enzymes and by increase of proline and soluble sugar content in leaves.

The role of irradiance on the activity of antioxidant enzymes: superoxide dismutase (SOD) and catalase (CAT) was examined in the leaves of Pisum sativum L. plants grown under low (LL) or high (HL) irradiance (PPFD 50 or 600 µmol m^-2 s^-1) and exposed after detachment to 5 mM Pb (NO₃)₂ for 24 h. The activities of both enzymes increased in response to LL compared with HL and no effect of Pb ions was observed. Photosystem (PS) 1 and PS 2 activities were also investigated in chloroplasts isolated from these leaves. LL lowered PS 1 electron transport rate and changes in photochemical activity of PS 1 induced by Pb²⁺ were visible only in the chloroplasts isolated from leaves of LL grown plants. PS 2 activity was influenced similarly by Pb ions at both PPFD. This study demonstrates that leaves of HL grown plants were less sensitive to lead toxicity than those from LL grown plants. Changes in electron transport rates were the main factors responsible for the generation of reactive oxygen species in the chloroplasts and as a consequence, in induction of antioxidant enzymes.

The use of two Agrobacterium tumefaciens strains for transformation of Triticum aestivum L. cv. Vesna was studied. Immature embryos, isolated 15 d after pollination, were co-cultivated with the super-binary LBA4404/pTOK233 and the binary AGL1/pDM805 vectors. While the transient GUS-intron expression was high (69.9 and 80.0 %), the number of plants regenerated on selective media containing hygromycin or phosphinotricin did not exceed 0.4 and 0.13 %, respectively. Nevertheless, the regenerated plants were fertile and produced seeds. The T₀ plants, as well as the T₁ seedlings, displayed the activity in the β-glucuronidase histochemical assay and a positive signal in PCR analysis for the presence of uidA gene sequences in their genomes. The data suggest that the transformation of wheat cv. Vesna with both Agrobacterium strains is feasible.

We investigated the impact of low pH and aluminum on the metabolism and capacity for Al accumulation in shoots of the plantain species Plantago algarbiensis and P. almogravensis. We found that increasing the concentration of Al in the medium increased accumulation of it in the shoots of both plants (although more in P. almogravensis than in P. algarbiensis). The presence of Al in the medium induced proline and saccharide synthesis in P. almogravensis without affecting lipid peroxidation, but increased proline synthesis and lipid peroxidation in P. algarbiensis without affecting the saccharide content. Lipid peroxidation in P. algarbiensis was also enhanced at pH 4.0. The activity of antioxidant enzymes was increased as a response to low pH and Al in both species. Our data indicate that both species can accumulate high levels of Al but they have different sensitivities to low pH and/or the presence of Al in the growth medium.

Somatic embryogenesis and plant regeneration were successfully established on Nitsch and Nitsch (NN) medium from immature zygotic embryos of six genotypes of grapevine (Vitis vinifera). The optimum hormone combinations were 1.0 mg dm^-3 2,4-dichlorophenoxyacetic acid (2,4-D) for callus induction and 1.0 mg dm^-3 α-naphthalene acetic acid (NAA) + 0.5 mg dm^-3 6-benzyladenine (BA) for embryos production and 0.03 mg dm^-3 NAA + 0.5 mg dm^-3 BA for embryos conversion and plant regeneration. The frequency of somatic embryogenesis varied from 10.5 to 37.5 % among six genotypes and 15.5-42.1 % of somatic embryos converted into normal plantlets. The analysis of DNA content determined by flow cytometry and chromosome counting of the regenerated plantlets clearly indicated that no ploidy changes were induced during somatic embryogenesis and plant regeneration, the nuclear DNA content and ploidy levels of the regenerated plants were stable and homogeneous to those of the donor plants. RAPD markers were also used to evaluate the genetic fidelity of plants regenerated from somatic embryos. All RAPD profiles from regenerated plants were monomorphic and similar to those of the field grown donor plants. We conclude that somaclonal variation is almost absent in our grapevine plant regeneration system.

Benzothiadiazole (BTH) is a structural analogue of salicylic acid (SA) which is widely recognized for its role in elicitation of systemic acquired resistance in a broad range of plant species. Here, BTH was applied to cell cultures of the bulbous ornamental plants Ornithogalum dubium and O. thyrsoides, showing a strong effect on rates of differentiation and morphogenesis. Morphogenic cell clusters in liquid Murashige and Skoog (MS) medium containing 1-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BAP) were used for all treatments. The calluses were washed thoroughly and activated with increasing concentrations of BTH. Following the induction, calli were grown on a solid MS medium without growth regulators (MS) or on a comparable media with NAA and BAP (M-206). The calli treated with BTH displayed a dose dependent increase in formation of meristematic centres followed by enhanced shoot formation compared to controls. Microscopic analyses revealed increased differentiation to cell organelles and a strengthening of the cell wall. A stronger response to BTH was observed in MS than in M-206 medium. A similar effect on calli differentiation was obtained by three weeks darkness followed by light exposure. The dark/light positive effect on differentiation was further augmented by BTH in a synergistic fashion. It is suggested that BTH enhances the rates of morphogenesis in Ornithogalum cultures by triggering a plant regulator-like activity.

To reveal the allelic differentiations at the two genes for fertility restoration (Rf) on chromosomes 1 (Rf3) and 10 (Rf4), 15 chromosome single segment substitution lines (SSSLs) with the Rf3 locus and 18 SSSLs with the Rf4 locus were crossed with Bobai A (BbA), a cytoplasmic male sterility line with wild abortive type of cytoplasm (WA-CMS), respectively. Based on the pollen and seed fertility of the F₁ hybrids, the Rf3 and Rf4 genes were each classified into four alleles, namely Rf3-1, Rf3-2, Rf3-3, and Rf3-4 for Rf3, and Rf4-1, Rf4-2, Rf4-3, and Rf4-4 for Rf4. Out of the 33 SSSLs, an SSSL W23-19-06-06-11 carrying the genotype Rf3-4Rf3-4/Rf4-4Rf4-4 possessed the strongest restoring ability for BbA. To determine the genetic effects of Rf3 and Rf4 for WA-CMS, one BC₃F₂ population possessing the genetic background of W23-19-06-06-11 was generated from the cross between W23-19-06-06-11 and BbA by backcrossing and marker-assisted selection. In the BC₃F₂ population, the plants carrying the Rf3Rf3/Rf4Rf4, Rf3Rf3/rf4rf4, and rf3rf3/Rf4Rf4 genotypes were selected and their phenotyping for pollen and spikelet fertility were evaluated. The result showed that under the genetic background of SSSL W23-19-06-06-11, the effect of Rf4 appeared to be slightly larger than that of Rf3 and their effects were additive for WA-CMS system. These studies will lead to the transfer of Rf genes into adapted cultivars through marker-assisted selection in active hybrid rice breeding programs.

Lingonberry (Vaccinium vitis-idaea L. ssp. vitis-idaea Britton) cultivars Regal, Splendor, and Erntedank were obtained by conventional softwood cuttings (taken as a control), by in vitro shoot proliferation of node explants, and by adventitious shoot regeneration from excised leaves of micropropagated shoots. In the plants propagated in vitro, the total ascorbate content increased and its pool was more oxidized, the total glutathione content also increased but its pool became more reduced. The leaves of plants obtained from the in vitro culture showed significantly higher antioxidant enzyme activities except for dehydroascorbate reductase which was at a similar level in all plants. Total soluble phenolics, tannins, and flavonoids were enhanced in fruits of in vitro-propagated plants whereas in leaves, the levels of these metabolites (except flavonoids) were higher in ex vitro derived plants. The total radical scavenging capacity was enhanced in berries of the in vitro propagated plants. It is suggested that the active morphogenetic process, characterized by intensive formation and scavenging reactive oxygen species is reflected in the activities of antioxidant enzymes and metabolites. The reduction potential of glutathione is the most important parameter which determines patterns of growth and differentiation in the investigated plants.

In Arabidopsis thaliana in vitro culture, shoots were induced from the shoot apical meristem (SAM) of germinating seeds in the presence of 2,4-dichlorophenoxyacetic acid. Primary shoot primordia developed leaf-like structures, from which secondary shoot primordia were produced. Regenerated shoots were recovered when the material was transferred to a medium lacking auxin. Adventitious roots formed from a callusing basal region of the secondary shoots. The CUC1 transcription factor was expressed at the apex of the primary shoot primordium and at the boundary between the regenerated SAM and the developing leaf primordia. The DR5::GUS transgene was used to localize sites of maximum auxin occurrence. Auxin was firstly detected in the dividing cells beneath the SAM epidermis, which coincided with sites where primary shoot primordia were initiated. In the regenerated shoots, auxin response was not detected in the basal region of the stem, suggesting that the regenerating structures were shoots rather than somatic embryos. Direct shoot regeneration from the A. thaliana SAM requires a localized accumulation of auxin.

Proteins WCS120 and DHN5 are known as the major cold-inducible dehydrins in wheat and barley plants, respectively. WCS120 and DHN5 relative accumulation increased exponentially along with a growth temperature decline in the range from optimum to cold temperatures. Even at optimum growth temperatures, the most frost-tolerant wheat and barley cultivars can be distinguished from the remaining ones according to dehydrin relative accumulation. The highly tolerant wheat and barley cultivars started accumulating dehydrins at higher growth temperatures and reached higher dehydrin amounts than the less tolerant ones. Statistically significant correlations between lethal temperature for 50 % of the samples (LT50) and dehydrin relative accumulation have been found at all growth temperatures (5, 10, 15 and 20 °C) for WCS120 in wheats and at 5 and 10 °C for DHN5 in barleys. Analogous relationships between dehydrin relative accumulation at different growth temperatures and plant acquired frost tolerance have been proved for wheat WCS120 and barley DHN5.

An efficient, rapid, and reproducible plant regeneration protocol was successfully developed for Abrus precatorius L. using mature nodal explants excised from a 5-year-old field grown plant. The highest shoot regeneration frequency (87 %) with maximum number of multiple shoots (15.0) and shoot length (4.8 cm) were recorded on Murashige and Skoog (MS) medium amended with 2.5 μM thidiazuron, 120 mg dm^-3 polyvinylpyrrolidone, and 0.5 μM α-naphthalene acetic acid. The best treatment for maximum root (4.0) induction was half strength MS medium supplemented with 1.5 μM indole-3-butyric acid. The in vitro plantlets with well-developed shoots and roots were successfully transferred into plastic cups with Soilrite and acclimatized in a culture room under photon flux density (PFD) of 150 μmol m^-2 s^-1, thereafter transferred to a greenhouse with PFD of 300 μmol m^-2 s^-1, and finally to a field with 70 % survival rate. During the acclimatization period (0-49 d), leaf chlorophyll and carotenoid content increased whereas malondialdehyde and H₂O₂ content decreased probably due to increasing activities of antioxidant enzymes (catalase, superoxide dismutase, glutathione reductase, and ascorbate peroxidase). Our work suggests that micropropagated plants developed an antioxidant enzymatic protective system to avoid oxidative stress during establishment under ex vitro environment.

Changes in membrane lipid composition is a fundamental strategy for plants to resist low-temperature stress. We compared members of 11 membrane glycerolipid classes in Thellungiella salsuginea and its close relative Arabidopsis thaliana at normal growth temperature, and during cold acclimation (CA), freezing (FR), and post-freezing recovery (PFR). The results showed several properties of T. salsuginea distinct from that in A. thaliana, which included: 1) low relative content of phosphatidic acid (PA) and a rapid increase and decrease of PA during FR and PFR respectively; 2) insensitivity of lyso-phospholipids to freezing; and 3) high ratio of phosphatidylcholine to phosphatidylethanolamine. All these properties were in favour of maintaining membrane integrity and stability and therefore enable T. salsuginea to be more tolerant to freezing than A. thaliana.

The aim of this study was to evaluate the influence of methylglyoxal (MG) on organogenesis and regeneration of tobacco (Nicotiana tabacum L.) plants from callus in media containing glycine or succinate. The best improvement in shoot proliferation and shoot length was obtained in the medium supplemented with 0.1 mM MG and 0.5 mM glycine or 0.25 mM succinate. The histological studies showed vigorous development of corm like structures and shoot organogenesis from callus tissues cultured in MG supplemented media. Biochemical studies also revealed higher content of δ-aminolaevulinic acid (a precursor of chlorophyll) and of chlorophyll.

Rice (Oryza sativa L.) seedlings were grown hydroponically in Hoagland's nutrient solution under controlled conditions to investigate the effects of NaCl pretreatment on their response to subsequent application of cadmium (Cd) alone and Cd + NaCl combination. The Cd stress caused growth retardation in all plants, significantly reduced pigment content, stomatal conductance (g_s), and net photosynthetic rate (P_N). Cd stress significantly increased malondialdehyde and proline content. Compared to Cd treatment alone, combination stress had more detrimental effects on the above parameters. However, the NaCl pretreatment was beneficial in improving the plant growth and plant tolerance to Cd alone or combination stress.

This study investigated the effects of pH and nitrogen form and concentration on cadmium (Cd) uptake by potato (Solanum tuberosum L.) grown in hydroponic culture. Potato plants grown in a pH-buffered nutrient solution for 10 d were exposed for 24 h to 25 nM CdCl₂ labelled with ¹⁰⁹Cd. Plants showed a significantly higher Cd uptake and accumulation at pH 6.5 than at pH 4.5 and 5.5. Nitrogen supplied as nitrate (NO₃ ^-) generally resulted in a higher Cd uptake and accumulation than N supplied as ammonium (NH₄ ⁺). This effect was most pronounced at pH 6.5. The N concentration increasing from 6.5 to 26 mM resulted in a decreased Cd influx when either NO₃ ^- or NH₄ ⁺ was used. Cd translocation to the shoot was increased when NO₃ ^- was used as the sole N source. In conclusion, pH had a strong influence on Cd uptake by roots and N form is especially important for Cd translocation within the potato plant.

Pepper (Capsicum annuum L.) plants were sprayed with salicylic acid (SA) and treated with ultraviolet radiation UV-A (320-390 nm), UV-B (312 nm), and UV-C (254 nm) of 6.1, 5.8, and 5.7 W m^-2, respectively. UV significantly reduced contents of chlorophyll (Chl) a and b, and carotenoids (Car). SA treatment moderated Chl and Car reduction in plants treated with UV-B and UV-C. The quantity of antocyanins, flavonoids, rutin, and UV-absorbing compounds in plants that were treated with UV-B, UV-C, and SA were significantly increased. Foliar spray of SA counteracted the UV effects on pepper.

Pea (Pisum sativum L.) somaclones of cultivars Adept, Komet and Bohatýr were obtained after selection in vitro with Fusarium solani filtrate and fusaric acid (FA). R2 regenerants were analysed by random amplification of polymorphic DNA (RAPD; OPAB4, P-14, UBC-556) and inter-retrotransposon amplification polymorphism (IRAP; Ogre) markers. Marker UBC-556 showed different banding patterns for each cultivar, but without specific bands for selected and control plants. Markers OPAB4, P14 and Ogre were useful for clear discrimination between selected and non-selected variants of all three cultivars. Flow cytometry analysis proved the same genome size of selected and non-selected pea lines. Therefore in vitro selection by pathogen derived agents could be the efficient method for obtaining of pea somaclones with increased resistance to F. solani.

Peanut plants exposed to water stress induced by polyethylene glycol (PEG) accumulated abscisic acid (ABA) and hydrogen peroxide (H₂O₂), the increase being significant at 12 and 24 h after addition, respectively. To address the question whether the increase in H₂O₂ production was related to ABA accumulation, the peanut leaves were pretreated with ABA biosynthesis inhibitor (sodium tungstate) and then exposed to water stress. Under these conditions, a decrease of ABA and H₂O₂ content were found after 12 h. The addition of 100 μM ABA restored H₂O₂ content reaching values similar to those under water stress at 12 h. We concluded that ABA accumulation is the first signal that triggers the H₂O₂ generation in peanut during first 12 h but its subsequent production is partially ABA-independent.