In this work the volatiles emitted from in vitro shoot-cultures and micropropagated plants of Lavandula viridis L'Hér. were characterized and compared with those obtained from the field-grown mother-plant, using headspace solid phase micro-extraction following by capillary gas chromatography coupled to mass spectrometry (HS-SPME-GC/MS). The headspace composition consisted mainly in oxygenated monoterpenes (66.7-79.2 %), where the major constituents emitted by the mature field-grown mother-plant, in vitro shoot-cultures and micropropagated plants were 1,8-cineole (74.0, 51.9 and 57.8 %) and camphor (2.9, 15.3 and 8.7 %), respectively. The headspace of in vitro shoot-cultures and micropropagated plants showed greater amount of α-pinene, camphene, β-pinene, β-selinene and selina-3,7(11)-diene, when compared with the field-grown mother-plant.

This study aimed to investigate the effects of irradiance on plant growth and content of proline and phytohormones during ex vitro acclimatization of micropropagated Ulmus minor plants. In vitro rooted plants were acclimatized to ex vitro conditions in a climate chamber with two irradiances, 200 μmol m^-2 s^-1 (high irradiance, HI) and 100 μmol m^-2 s^-1 (low irradiance, LI) for 40 d. Immediately after the ex vitro transfer, the plants experienced a water deficit [wilting leaves with the reduced relative water content (RWC)], but following the experiment, the recovery of the RWC was more pronounced in the HI treatment. Also, the content of proline, ABA, and JA-Ile were higher in HI treatment. Growth analyses revealed that HI improved growth and biomass production.

Acyl carrier protein (ACP), as an essential protein cofactor, plays an important role in de novo synthesis of fatty acids in plastids. In this study, the expression profile of peanut (Arachis hypogaea) AhACP1-1 and AhACP1-2 was analyzed in different tissues. The expression level of AhACP1-1 was highest in the seed, whereas expression was barely detected in the shoot, and AhACP1-2 was expressed in every tissue analyzed with the highest expression level detected in the leaf and seed. Overexpression (OE) and antisense-inhibition (AT) of AhACP1 in transgenic tobacco modified the transcript level of endogenous NtACPs, and the content of total lipids and composition of fatty acid in leaves were altered compared with the wild-type control. Transgenic OE-AhACP1 or AT-AhACP1 tobacco exhibited a significant increase or decrease in polyunsaturated C18:2 and C18:3 fatty acid content, and were more tolerant or sensitive to cold stress, respectively. It is suggested that AhACP1 bound with C18:1 might be the specific substrate of oleoyl-ACP thioesterase or glycerol-3-phosphate acyltransferase, and participates in membrane lipid synthesis.

Trehalose can reduce stomatal aperture by a hydrogen-peroxide-dependent pathway in Vicia faba L. (cv. Daqingpi) resulting in significantly lower values of net photosynthetic rate (P_N), stomatal conductance (g_s), and transpiration rate (E). At 8 and 24 h, the lower P_N in trehalose-treated plants was accompanied by significant decrease in intercellular CO₂ concentration (c_i) suggesting that the reduction of P_N was caused by stomatal limitation. At 48 and 72 h, trehalose decreased apparent carboxylation efficiency (P_N/c_i) and did not decrease c_i and g_s compared with controls; therefore the reduction in photosynthesis was caused by non-stomatal limitation. Trehalose treatment resulted in significantly higher effective photochemical efficiency of PS II (Φ_PSII) and did not affect maximum photochemical efficiency of PS II (F_v/F_m). At 24, 48, and 72 h, trehalose decreased non-photochemical quenching (NPQ) and increased photochemical quenching (qP). Our results suggest that trehalose did not damage photosynthetic reaction centers.

The rice OsMyb4 gene, which encodes a Myb transcription factor (TF), improves the stress tolerance/resistance when expressed in both monocotyledonous and dicotyledonous transgenic plants. In this study, a phylogenetic analysis showed the existence of putative OsMyb4 homologues in monocot and dicot species. In particular, the analysis revealed that OsMyb4 belongs to a small rice gene subfamily conserved among monocots. The expression analyses of the OsMyb4-like genes in rice, wheat, and Arabidopsis indicated that these genes are involved in the response to dehydration, cold, and wounding. Moreover, the in silico analysis of the 5' upstream regions of the Osmyb4-like genes highlighted that the positions of some cis-elements involved in the stress response were conserved among the putative promoters, especially between OsMyb4 and its putative paralog Os02g41510. Finally, our transient expression assays in tobacco protoplasts demonstrated that OsMyb4 is able to repress the activity of both its own promoter and the Os02g41510 promoter by acting on the same binding site. A compensatory mechanism of auto-regulation is consistent with the well-known complexity of the OsMyb4-activated pathway, and this mechanism could regulate the transcription of other genes belonging to the family.

A new ethylene response factor (ERF), GmERF6, was isolated from soybean. Protein sequence alignment of GmERF6 revealed an AP2/ERF domain, two putative nuclear localization signals (NLSs) and an ERF-associated amphiphilic repression (EAR) motif. Real-time quantitative PCR analysis revealed that the expression of GmERF6 was differentially induced in soybean seedlings by drought, salt, cold, salicylic acid, ethylene, abscisic acid and methyl jasmonate. Transient expression experiments demonstrated that GmERF6 functions as a transcriptional repressor to downregulate the transcriptional levels of the reporter gene and repress the activated ability of other transcriptional activator. Transgenic Arabidopsis lines constitutively expressing GmERF6 showed an increased tolerance to drought compared to wild-type plants.

The alleviative effects of exogenous calcium on copper phytotoxicity were investigated in Elodea canadensis plants. There was a significant accumulation of Cu in the plants after their exposure to 0.01 mM Cu accompanied by many symptoms of toxicity. Increased uptake of Cu severely reduced content of photosynthetic pigments, soluble proteins, and free proline. The total antioxidant capacity (T-AOC), reduced glutathione (GSH), and non-protein thiol (NP-SH) were severely suppressed in Cu-stressed plants resulting in a rapid increase in content of superoxide anion (O₂ ^.-), hydrogen peroxide, lipid peroxidation, and cell death. Simultaneous application of Ca markedly increased the content of photosynthetic pigments, soluble proteins, free proline, T-AOC, GSH, and NP-SH, and reduced oxidative damage as indicated by lowered content of MDA, O₂ ^.-, and H₂O₂; and decreased cell death. Furthermore, application of Ca reduced Cu uptake and effectively reversed the Cu-induced nutrient imbalance.

The effects of paclobutrazol (PBZ) on the ex vitro transfer efficiency of in vitro grown Dendrobium nobile seedlings were investigated. The survival percentage was increased by 41.6 % with 0.8 mg dm^-3 PBZ treatment compared to controls. The PBZ-treated D. nobile plants were shorter than control plants. Morphological and anatomical analyses showed that root diameter, especially at the root apex, became larger after treatment with PBZ which is consistent with the increases in cortical cell sizes and row numbers. In addition, the first observations of thickened velamen of the PBZ-treated seedling were made in the present study. The activities of cellulase and indole acetic acid oxidase increased in PBZ-treated plantlets, whereas that of cell wall-associated peroxidase declined compared to controls. The content of endogenous gibberellic acid and iso-pentenyladenosine of root tips changed little by PBZ but that of indole-3-acetic acid decreased by 53 %. These results indicated that PBZ could improve the transfer efficiency of D. nobile from in vitro culture to pots due to its effects on root development.

Water relations, mineral composition, growth and root morphology were studied in pepper plants (Capsicum annuum L. cv California Wonder). Two NaCl concentrations (30 and 60 mM) and two nutrient solutions in which the concentrations of macronutrients were increased were used to assess the ionic and osmotic effects of NaCl in these plants. The hydraulic conductivity (L_o), stomatal conductance (g_s), percentage of open stomata and pressure potential (Ψ_p) decreased with all treatments, in a similar way for 30 mM NaCl and for its iso-osmotic solution of macronutrients, however, the decrease was higher for 60 mM NaCl than for its iso-osmotic solution. Ion analyses also revealed that nutrient concentrations were altered greatly at 60 mM NaCl. Also, changes in morphology, such as increases in cortex cell size and in intercellular spaces, were detected. Therefore, at low salinity, the effect of NaCl was mainly osmotic, however, under higher salinity also the toxicity of Na⁺ and Cl^- participate.

In different plant species, vanadium has been considered either as beneficial or as a toxic element, or even as secondary metabolism elicitor, but the mechanisms involved are still not completely understood. In this study, the responses of Phaseolus vulgaris L. cv. Contender roots and leaves to different vanadyl sulfate concentrations were studied. The plants grown hydroponically with V had thicker roots, a less developed main root, and a smaller number of secondary roots than the control plants. The V content in roots and leaves was correlated with V supply concentration but the V content in leaf was always much lower than in the root, which leads us to conclusion that V accumulates in the roots and only small quantities are transferred to the leaves. However, thylakoid disorganisation was observed in the chloroplasts of plants grown with vanadyl sulphate.

Using aseptic plantlets obtained from stem node explants of hybrid red miniature rose (Rosa hybrida cv. Fairy Dance), the effects of shoot physiological status, medium ingredients, and culture thermoperiod on in vitro flowering were evaluated. Shoot height, subculture media for shoot multiplication, sucrose concentration, plant growth regulators (PGRs), mineral substances in media, and thermoperiod had a significant effect on the percentage of in vitro flowering. Shoots 3 ± 0.2 or 2 ± 0.2 cm in height cultured on Murashige and Skoog (MS) medium containing 2.0 mg dm^-3 6-benzyladenine (BA), 0.2 mg dm^-3 α-naphthaleneacetic acid (NAA), and 20 g dm^-3 sucrose were more suitable for in vitro flowering than shoots 4 ± 0.2, or 5 ± 0.2 cm in height. The most suitable sucrose concentration for in vitro flowering was 50 g dm^-3 and the most suitable PGRs were a combination of 3.0 mg dm^-3 BA and 0.1 mg dm^-3 NAA. Increasing the potassium nitrate to ammonium nitrate ratio or increasing the phosphate concentration in MS medium had a positive effect on in vitro flowering. The percentage of in vitro flowering was significantly higher at day/night temperature of 28/20 °C than at other constant temperatures. The percentage of in vitro flowering shoots reached 68.33 % despite the occurrence of abnormal flowers and some unique developmental patterns. It makes miniature rose a potentially new in vitro experimental platform for research on the molecular mechanisms of flowering ornamental plants.

The effects of plant growth regulators (PRGs) on the induction of flowering and sex expression in micropropagated cucumbers are presented. The highest number of male flowers (6.0 ± 0.7 per plant) was produced by cv. Kmicic F1 on the Murashige and Skoog (MS) medium supplemented with 4.0 μM kinetin. The highest number of female flowers (3.1 ± 0.3) was also observed in cv. Kmicic F1 on either control (PRG-free) medium or medium supplemented with 6.4 μM indole-3-acetic acid (IAA). The MS medium supplemented with 4.4 μM benzyladenine inhibited flower formation. The highest percentage of flowering plantlets (67.5 ± 7.5) was observed on the control MS medium after 16 weeks of culture. Female-to-male flower ratio was influenced by the culture media and changed during cultivation. The highest pollen viability (60-70 %) was observed in anthers of plants cultured on the control medium and the medium with IAA.

The manipulation of cytokinin contents via Agrobacterium-mediated transformation is an efficient tool for delaying leaf senescence and improving the resistance to environmental stresses. In the present study, cotton transformants harbouring the Agrobacterium tumefaciens isopentenyl transferase (IPT) gene under the control of the promoter of Gossypium hirsutum cysteine proteinase (Ghcysp) were generated. PCR and Southern blot analysis indicated that the foreign DNA fragment was successfully integrated into the cotton genome. The chlorophyll and cytokinin contents, and ROS-scavenging enzymatic activities were significantly increased in transgenic cotton lines, which resulted in a significant delay in leaf senescence. The growth characteristics of transgenic cotton lines resembled the non-transgenic lines except delaying premature senescence and the lint yield and fiber quality of transgenic lines were improved. In addition, the transgenic lines had higher biomasses, IPT transcripts, and endogenous cytokinin contents compared with those of non-transgenic lines under 200 mM NaCl stress.

The effect of cadmium on growth and contents of glutathione (GSH) and phytochelatins (PCs) were investigated in roots and leaves of tomato plants (Lycopersicon esculentum Mill. cv. 63/5 F1). The accumulation of Cd increased with external Cd concentrations and was considerably higher in roots than in leaves. Dry mass production decreased under Cd treatment especially in leaves. In both roots and leaves, exposure to Cd caused an appreciable decline in GSH contents and increase in PCs synthesis proportional to Cd concentrations in the growth medium. At the same Cd concentration, PCs production was higher in roots than in leaves. The implication of glutathione in PC synthesis was strongly suggested by the use of buthionine sulfoximine (BSO). The major fraction of Cd accumulated by tomato roots was in the form of a Cd-PCs complex.

The effect of nitrogen forms on photosynthesis and anti-oxidative systems of barley plants under chromium stress was studied in a hydroponic experiment. The treatments comprised three chromium concentrations (0, 75, and 100 μM) and three N forms (NH₄)₂SO₄, urea, and Ca(NO₃)₂. In comparison with the urea or (NH₄)₂SO₄ fed plants, the Ca(NO₃)₂ fed plants had higher net photosynthetic rate, intercellular CO₂ concentration, stomatal conductance, transpiration rate, photosynthetically active radiation utilization efficiency, variable to maximum chlorophyll fluorescence ratio, and the content of chlorophylls and carotenoids. Cr toxicity caused oxidative stress in all plants but the Ca(NO₃)₂ fed plants had the least oxidative stress. Moreover, the Ca(NO₃)₂ fed plants had higher activities of anti-oxidative enzymes and content of non-enzymatic antioxidants than the urea or (NH₄)₂SO₄ fed plants. In addition, the Ca(NO₃)₂ fed plants had higher N and lower Cr content in all plant tissues than the urea or (NH₄)₂SO₄ fed plants. The current results indicate that the reasonable choice of N fertilizer is important for barley production on the Cr-contaminated soils.

The coat protein gene isolated from Papaya ringspot virus, Thai isolate, was used to generate transgenic papayas. A binary vector containing the coat protein gene under the control of a 35S promoter, was constructed and transformed into somatic embryos of papaya cultivar Khak Dum by microprojectile bombardment. Eight transgenic lines were identified from 1980 bombarded calli of papaya somatic embryos under kanamycin selection. Integration of the transferred genes into kanamycin resistant papaya calli was verified by PCR amplification of the coat protein gene, GUS assays and Southern blot hybridization. Although the coat protein gene was detected in all transgenic lines, only line G2 was found to be highly resistant to virus. This resistant line showed high degree of rearrangement of the inserted coat protein expression cassette while the coat protein gene itself had a deletion of 166 bp on the 3' end of its sequence. Although the transcription of the coat protein gene was detected in all transgenic lines by RT-PCR, only two transgenic papayas expressed the intact coat protein. Moreover, in the resistant line G2 the amount of the truncated coat protein mRNA was significantly decreased. These results point to an RNA mediated mechanism of coat protein mediated resistance in papaya, probably based on post-transcriptional gene silencing.

In order to set up large-scale acclimatization protocols of micropropagated plants, an in-depth knowledge of their physiological responses during in vitro to ex vitro transfer is required. This work describes the photosynthetic performance of Ulmus minor micropropagated plants during acclimatization at high irradiance (HI; 200 ± 20 μmol m^-2 s^-1 or low irradiance (LI; 100 ± 20 μmol m^-2 s^-1). During this experiment, leaf pigment content, chlorophyll a fluorescence, gas exchange, stomata morphology, the activity of the Calvin cycle enzymes and saccharides were measured in persistent and new leaves. The results indicated that HI induces a higher photosynthetic performance compared to LI. Therefore, plants acclimatized under HI are likely to survive better after field transfer.

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.

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.

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 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.