Bacillus cereus C1L was demonstrated to induce systemic resistance in Lilium formosanum against leaf blight caused by Botrytis elliptica. Suppression subtractive hybridization library of L. formosanum triggered by B. cereus C1L were screened and 3 differentially expressed genes were identified. Based on sequence analysis, these genes encoding putative glycine-rich protein, metallothionein-like protein, and PsbR protein of photosystem 2, were designated LfGRP1, LfMT1, and LfPsbR, respectively. The results of Northern blot analysis showed that expressions of LfGRP1, LfMT1 and LfPsbR increased in response to B. elliptica infection. On the other hand, expression of LfMT1 increased but expressions of LfGRP1 and LfPsbR decreased when the rhizosphere of L. formosanum was drenched with suspension of B. cereus C1L with or without subsequent challenge with B. elliptica on lily leaves. Similar expression profiles of homologues of LfGRP1, LfMT1, and LfPsbR (named LsGRP1, LsMT1, and LsPsbR, respectively) were presented in Lilium oriental hybrid Star Gazer. In addition, application of the photosynthetic inhibitor, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, on the leaves reduced disease severity and expressions of LsGRP1 and LsPsbR just as that in response to B. cereus C1L treatment.

An experiment was conducted with two contrasting pigeon pea (Cajanus cajan L.) genotypes, ICPL 84023 (tolerant) and ICP 7035 (susceptible), to study the physiological and molecular basis of waterlogging tolerance in relation to oxidative stress and antioxidant enzyme activities. Waterlogging resulted in visible yellowing and premature senescence of leaves, and greater decline in relative water content, chlorophyll content, and membrane stability index in ICP 7035 than in ICPL 84023. Superoxide radical and hydrogen peroxide contents increased at day 4 and 6 of waterlogging probably due to activation of NADPH-oxidase. O₂ ^.- production was inhibited, by diphenylene iodonium chloride, a specific inhibitor of NADPH oxidase and expression of NADPH oxidase-mRNA was increased under waterlogging condition in ICPL 84023. ICP 7035 showed higher contents of ROS in control condition and after recovery, however, during waterlogging the O₂ ^.- production was higher in ICPL 84023. Activities of antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase and catalase increased under waterlogging more in ICPL 84023 than in ICP 7035. Cu/Zn-SOD and APX-mRNA expression in 24-h waterlogged plants showed enhanced expression in ICPL 84023 compared to ICP 7035. The cloning and sequencing of APX gene of tolerant and susceptible genotypes yielded cDNAs of 622 and 623 bp, having 95 % homology with each other and 92 % with the corresponding sequences of Vigna unguiculate APX-gene.

The full-length cDNA of LeSGR1 was cloned from tomato by RT-PCR and RACE. The cDNA encoded a protein of 272 amino acid residues and was deposited in GenBank (accession No. DQ100158). Northern analysis suggests that LeSGR1 gene specifically expresses in senescent leaves and mature fruits of tomatoes. Desiccation and flooding induce the expression of LeSGR1 in tomato leaves and stems. Both in ethylene-insensitive mutants (Nr) and ripening inhibitor mutants (rin), the expression of LeSGR1 is markedly decreased compared with that in the wild type. Alignment of the nucleotide sequence of SGR1 cloned from the tomato green flesh (gf) mutant with that from the wild type tomato shows a single nucleotide change leading to an amino acid substitution in gf mutant. Furthermore, LeSGR1 gene silencing by RNA interference results in inhibited chlorophyll degradation similar to the phenotype in gf mutant. Thus, we conclude that LeSGR1 is crucial to chlorophyll degradation and the mutation of SGR1 protein might be responsible for gf tomato properties.

Protoporphyrinogen oxidase (Protox) in the porphyrin pathway is the target site of the peroxidizing herbicides such as carfentrazone-ethyl and oxyfluorfen. In an attempt to develop herbicide-resistant plants, transgenic rice plants were generated via expression of herbicide-insensitive Bacillus subtilis Protox gene fused to the transit sequence for targeting to the plastid using Agrobacterium-mediated gene transformation. Homozygous transgenic rice lines of T₃ generation selected by hygromycin resistance test were examined if they are resistant to the herbicides carfentrazone-ethyl and oxyfluorfen. The homozygous transgenic lines had single copy insertion of B. subtilis Protox gene into their genomes and express its mRNA. Compared to wild-type rice, the transgenic lines were less susceptible to the herbicides when examined with respect to growth, electrolyte leakage, chlorophyll loss and lipid peroxidation. The in vitro Protox activities in transgenic lines were about 56 % higher than those in wild-type rice. With 10 µM concentration of the herbicides in the enzyme assays, Protox activities in transgenic lines were similar to those in non-inhibited wild-type rice. Less amount of protoporphyrin IX was accumulated in transgenic lines than in wild-type rice upon the treatment of the herbicides at 10 µM concentration. Our results indicated that expression of B. subtilis Protox gene was stably transmitted into T₃ rice plants and reduced their sensitivity to carfentrazone-ethyl and oxyfluorfen.

Vigna Δ¹-pyrroline-5-carboxylate synthetase (P5CS) cDNA was transferred to chickpea (Cicer arietinum L.) cultivar Annigeri via Agrobacterium tumefaciens mediated transformation. Following selection on hygromycin and regeneration, 60 hygromycin-resistant plants were recovered. Southern blot analysis of five fertile independent lines of T0 and T1 generation revealed single and multiple insertions of the transgene. RT-PCR and Western blot analysis of T0 and T1 progeny demonstrated that the P5CS gene is expressed and produced functional protein in chickpea. T1 transgenic lines accumulated higher amount of proline under 250 mM NaCl compared to untransformed controls. Higher accumulation of Na⁺ was noticed in the older leaves but negligible accumulation in seeds of T1 transgenic lines as compared to the controls. Chlorophyll stability and electrolyte leakage indicated that proline overproduction helps in alleviating salt stress in transgenic chickpea plants. The T1 transgenics lines were grown to maturity and set normal viable seeds under continuous salinity stress (250 mM) without any reduction in plant yield in terms of seed mass.

A simple and reliable regeneration system from leaf bases of barley (Hordeum vulgare L.) has been developed. The in vitro regeneration frequencies of seven commercial barley genotypes were compared using segments from the first leaves of 5-d-old seedlings. The regeneration frequency ranged from 31.56 to 72.22 % among the barley genotypes. Murashige and Skoog medium supplemented with 6-benzyladenine (0.5 mg dm^-3) and kinetin (0.5 mg dm^-3) was optimum for the regeneration. Longitudinal cut of the segments or the removal of coleoptiles further increased plantlet regeneration frequency.

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.

Tobacco (Nicotiana tabacum L.) plants were cultured in vitro photoautotrophically at three levels of irradiance (PAR 400-700 nm): low (LI, 60 µmol m^-2 s^-1), middle (MI, 180 µmol m^-2 s^-1) and high (HI, 270 µmol m^-2 s^-1). Anatomy of the fourth leaf from bottom was followed during leaf development. In HI and MI plants, leaf area expansion started earlier as compared to LI plants, and both HI and MI plants developed some adaptations of sun species: leaves were thicker with higher proportion of palisade parenchyma to spongy parenchyma tissue. Furthermore, in HI and MI plants palisade and spongy parenchyma cells were larger and relative abundance of chloroplasts in parenchyma cells measured as chloroplasts cross-sectional area in the cell was lower than in LI plants. During leaf growth, chloroplasts crosssectional area in both palisade and spongy parenchyma cells in all treatments considerably decreased and finally it occupied only about 5 to 8 % of the cell cross-sectional area. Thus, leaf anatomy of photoautotrophically in vitro cultured plants showed a similar response to growth irradiance as in vivo grown plants, however, the formation of chloroplasts and therefore of photosynthetic apparatus was strongly impaired.

A glutathione S-transferase (GST) gene cloned from the lepidopteran spruce budworm, Choristoneura fumiferana Clem. was transformed into the model plant Arabidopsis thaliana. The CfGST-transgenic and wild-type A. thaliana were subjected to 4 and 10 °C for 48 h and their cold resistance was studied. The GST activity of the transgenic plants was 46.6 and 35.7 % higher than that of the wild-type plants after 48 h under 4 and 10 °C, respectively. Relative membrane permeability and malondialdehyde content in the transgenic plants were lower while contents of the chlorophyll and proline were higher than those in the wild-type plants under 4 and 10 °C. The survival rate of the transgenic plants was 43.7 % for 24 h under 0 °C, while survival rate of wild-type plants was 28.3 %. The results indicated that the insect GST could enhance cold resistance in the transgenic A. thaliana.

There are significant changes in the structure of the upper tobacco (Nicotiana tabacum L.) leaves systemically infected with tobacco mosaic virus (TMV) especially in the light green tissue (LGT). Dark green areas (DGI) had intermediate status between healthy tissue and LGT. DGI contained significantly less infectious TMV and viral antigen than the LGT. The DGI, LGT and healthy tissues did not differ in the permeability of cell membranes and in the set of acidic pathogenesis-related (PR) proteins but the total content of PR-proteins in the healthy plants was higher than in the infected ones with the DGI being intermediate between healthy tissue and LGT. The crude leaf extracts from DGI and LGT showed less total ribonuclease activity and ribonuclease isozymes in comparison with control.

Studies on cadmium effects in the root meristematic cells of Allium sativum L. were carried out using electron microscopy in order to explain the possible mechanisms of garlic seedlings' tolerance to Cd stress. Seedlings were treated with 0.01, 0.10 and 1.00 mM CdCl₂ solutions for 0.5, 1, 2, 4, 8, 10, 12, 24 and 48 h, respectively. The results indicated that cell walls, plasma membrane and main organelles actively participated in Cd detoxification and tolerance at low Cd concentrations. Once excessive Cd ions entered the cytosol, a defence mechanism becomes activated, protecting the cells against cadmium toxicity. However, under high Cd content in cells, the cell structure was damaged, even leading to cells death.

In order to study chloroplast biogenesis, we chose natural variegated Epipremnum aureum (golden pothos) and regenerated pale yellow, variegated and green plants from all three types of tissue explants. The percentage of three types of regenerated shoots from three different explants was very close. Regenerated plants have been maintained for a year and show no sign of a colour switch. By comparing their protein profiles, two major differences between pale yellow and green plants were observed at the 15 and 40 to 50 kDa proteins. Moreover, pale yellow plants had unexpected high molecular mass proteins (greater than 60 kDa). Both variegated and green plants had more chlorophyll (Chl) a than Chl b, the ratios were about 1.46 and 1.93, respectively. In contrast, the pale yellow plants not only had less total Chl, but also the reduction of Chl a was much greater than Chl b, resulting in a higher content of Chl b than Chl a. Microscopic analysis revealed that pale yellow plants contained predominantly undeveloped chloroplasts with low Chl contents, even though their mesophyll cells were similar to green and variegated plants. PCR amplification of chloroplast DNA with 14 universal chloroplast primers did not reveal any difference among these regenerated plants.

Twenty accessions of the sparsely cultivated diploid Musa cultivars Matti (AA) and Rasakadali (AB) were subjected to random amplified polymorphic DNA (RAPD) assay. A total of 14 random primers were used for the estimation of interand intracultivar variations. Out of 86 bands generated, 64 were polymorphic (74.4 % polymorphism). The cluster analysis grouped the cultivars into two major clusters: cluster I with 10 accessions of Matti and 2 of Rasakadali and cluster II comprising the remaining 8 accessions of Rasakadali. The coefficient of genetic similarity (GS) was from 0.73 to 0.99, suggesting low level of intercultivar variation. The accessions of Rasakadali with mean GS of 0.89 were genetically more diverse than those of Matti (GS = 0.93).

To characterize the low molecular mass glutenin subunit gene 177-21 (AY994364) in wheat (Triticum aestivum L. cv. Jinan 177), we developed a specific PCR primer set to decide its locus with nullisomic-tetrasomic lines of Chinese spring wheat. The result showed that it was assigned to Glu-D3. The DNA fragment of 177-21 was then subcloned into the pGEX-4T-1 expression vector and expressed in E. coli with isopropyl-1-thio-β-D-galactoside induction. The result indicated that this gene encodes about 30 kD polypeptide and deduced amino acid sequence consists of eight cysteine residues. Of the eight, six may be related with the formation of intra-molecular disulfide bonds, the last two with the formation of inter-molecular disulfide bonds, which could be a potential extender in "glutenin polymer" to have positive influence on quality of wheat flour.

A near isogenic line (NIL) of Brassica oleracea var. botrytis with resistant and susceptible lines C712 and C731, was used in this study. More than 100 differentially expressed cDNA fragments were obtained from black rot resistant cauliflower plants obtained using cDNA-amplified fragment length polymorphism (AFLP) after infection with the pathogen. Thirteen of these fragments were cloned and subjected to reverse Northern blot analysis using both infected and control cDNA pools. Two positive clones, M2 and M6, were isolated. Northern dot blot and Northern blot analyses showed that M2 was constitutively expressed, whereas M6 contained a gene that was differentially expressed during pathogen infection. Moreover, M6 cDNA fragment was also highly expressed 16-24 h after H₂O₂ treatment. Southern blots showed that M6 is a single copy gene in the cauliflower genome, and encodes a protein with 84 % homology to gene on Arabidopsis chromosome 1. The deduced M6 protein has 91 % positive homology with the Arabidopsis 2A6 protein, which regulates ethylene synthesis; 76 % homology with a 1-aminocyclopropane-1-carboxylate oxidase (ACO), the last enzyme in ethylene synthesis; and 70 % homology with an ethylene induced DNA binding factor. These results suggest that M6 gene fragment is a new H₂O₂ downstream defense related gene fragment and can be induced by Xanthomonas campestris pv. campestris and H₂O₂.

In 7-d-old seedlings of Brassica juncea chromium (VI) promoted photosystem 2 (PS 2) mediated photoreactions. The increase in PS 2 activity in the thylakoids from Cr-treated seedlings, in the presence of uncoupler (5 mM NH₄Cl), was similar to that recorded with the control thylakoids. Thus Cr enhanced PS 2 activity was not due to uncoupling of electron transport from photophosphorylation. Photon saturation kinetics revealed that the PS 2 activity of thylakoids from Cr-treated seedlings was significantly higher at almost all irradiances in comparison to that of controls. PS 2 activity of thylakoids from Cr-treated plants at 25 % of the saturating irradiance was in par with the PS 2 activity of the thylakoids from control plants at saturating irradiance. Thylakoids from both control and Cr-treated seedlings exhibited maximum PS 2 activity at pH 7.5. The PS 2 activity of thylakoids from Cr-treated plants remained high even at pH 8.0 and 8.5, demonstrating Cr enhances tolerance of PS 2 to alkaline pH.

In order to better understand the role of cold acclimation in alleviating freezing injury, two barley cultivars with different cold tolerance, i.e. a sensitive cv. Chumai 1 and a tolerant cv. Mo 103, were used. The freezing treatment increased leaf soluble protein content more in the tolerant cultivar than in the sensitive one. Cold acclimation increased H₂O₂ content of the two cultivars during freezing treatment, especially in Mo 103. Glutathione and ascorbate contents during freezing and recovery were significantly higher in cold-acclimated plants than in non-acclimated ones. Activities of peroxidase, ascorbate peroxidase and glutathione reductase were also higher in cold-acclimated plants than non-acclimated plants during freezing treatment. However, there was no significant difference between cold-acclimated plants and the control plants in catalase activity. It may be assumed that cold acclimation induced H₂O₂ production, which in turn enhanced activities of antioxidative enzymes and synthesis of antioxidants, resulting in alleviation of oxidative stress caused by freezing.

An efficient micropropagation protocol for annatto (Bixa orellana L.) was achieved using nodal shoot tip explants. Shoot buds were obtained on the Murashige and Skoog (MS) medium supplemented with various concentrations and combinations of indole-3-acetic acid (IAA), N⁶-benzyladenine (BA) and triacontanol (TRIA). Maximum of 213 shoot buds along with 18 primary shoots were produced on MS medium containing 0.05 µM IAA, 8.87 µM BA, and 11.2 µM TRIA. The primary shoots elongated best on MS medium containing 6.66 µM BA and 2.45 µM indole-3-butyric acid (IBA). The regenerated shoots rooted best on MS medium supplemented with 4.9 µM IBA. The in vitro rooted plantlets were hardened and establishment rate under field conditions was 70 to 80 %.

In order to evaluate effects of γ-rays on adventitious root formation and ginsenoside production, embryogenic calli induced from cotyledon explants of Panax ginseng C.A. Meyer were treated with γ-rays of 0, 10, 30, 50, 70, and 100 Gy. The highest frequency of adventitious root formation of 75 % occurred at γ-irradiation of 30 Gy, which is considered adequate dosage for selecting mutant cell lines. Five mutated adventitious roots (MAR)3-lines out of the propagation of 142 adventitious root lines treated with 30 Gy were selected based a 100-fold increase in proliferation rate compared to control adventitious roots (CAR) and content of the seven major ginsenosides (Rb₁, Rb₂, R_c, R_d, R_e, R_f, and Rg₁) was determined. In the CAR and four of the MAR3-lines (except for MAR3-109), the Rb/Rg ratio was greater than 1.0, thereby indicating altered ginsenoside composition in these root lines. The HPLC analysis of the MAR3-13 and MAR3-26 lines confirmed different ginsenoside profiles, including the three unidentified ginsenoside candidates, Gm₁, Gm₂, and Gm₃. The ginsenosides of the MAR3-13 and MAR3-26 lines showed high hydroxyl and superoxide radical scavenging activities.

Specific activities and isoform patterns of peroxidases, acid phosphatases, DNases and RNases were studied in relation to in vitro rooting of Petunia × hybrida microshoots in the presence of 4 µM indole-3-butyric acid (IBA). Specific activities of the above enzymes increased in the course of rooting. Rhizogenesis could be related with an increased specific activity of peroxidases during the initiation phase, in parallel with increased lignin content. Twelve peroxidases, six anionic (A1-A6) and six cationic (C1-C6), seven acid phosphatases (ACP1-ACP7), seven RNases (R1-R7) and four DNases (D1-D4) isoforms were detected following native PAGE. Variation in the number of the above isoforms and their quantity was observed during different stages of rooting. Particularly, A2, A3, C3, C4, C5, ACP2, R1, R2, R3, and D4 isoforms appeared after the induction phase and could be related to emergence of root primordia. Additionally, R3 and D4 could be associated with cell division and differentiation, since these are only expressed in rooted microshoots. Moreover, the higher number of roots in IBA-treated microshoots could be related to the higher expression of RNase and DNase isoforms during initiation and expression phases.

Cuttings from two contrasting Populus cathayana Rehder populations originating from Hanyuan (wet climate) and Ledu (dry climate) in western China were grown in a greenhouse to determine the effects of drought, shade and their interaction on the morphological and physiological traits of leaves. The dry climate population was more droughttolerant than the wet climate population, as indicated by smaller decreases in the leaf relative water content (RWC) and net photosynthetic rate (PN), as well as by greater increases in antioxidative enzyme activities and free proline content under drought. On the other hand, the negative effects of shade on leaf traits were more pronounced in the dry climate population, which suggested that the dry climate population was more light-demanding. In addition, moderate shade alleviated the drought stress of P. cathayana not only by improving the leaf RWC but also by maintaining the positive carbon balance. In contrast, severe shade aggravated drought stress as indicated by a pronounced decrease in leaf size, carbon and nitrogen contents, maximum PN, free proline content and antioxidative enzyme activities.

An attempt has been made to determine if drought-induced proteins could be used as a selection marker to differentiate between tolerant and sensitive cultivars. Three Indian tomato (Lycopersicon esculentum Mill.) cultivars (Pusa Ruby, Arka Vikas and Pusa Early Dwarf) were subjected to drought stress in vivo as well as in vitro and the pattern of polypeptide expression was determined using one-dimensional SDS-PAGE. In all the three cultivars, a new 29 kDa polypeptide accumulated in leaves, in response to gradual drought stress and its accumulation was fastest in Pusa Ruby. Drought stress also resulted in an increase in ion leakage from leaf discs of all the three cultivars but the rate was lower in Pusa Ruby than in other two. Therefore, it was concluded that Pusa Ruby is most tolerant to drought stress among the three tomato cultivars investigated.

To reveal the maternal donor of species in genus Kengyilia, the chloroplast trnL-F sequences of 14 Kengyilia species and several related diploid species were analyzed by using Maximum Parsimony (MP) and Bayesian Inference (BI) methods. The species in Kengyilia were clustered in different clades, which indicated that Agropyron (P) is the likely maternal genome donor to Kengyilia melanthera, K. mutica and K. thoroldiana, while the maternal donor to Kengyilia batalinii, K. nana, K. kokonorica, K. kaschgarica, K. hirsuta, K. alatavica, K. gobicola, K. zhaosuensis, K. rigidula, K. longiglumis and K. grandiglumis was St or Y Roegneria genome.

Molecular farming provides a powerful tool for low cost production of recombinant proteins with pharmaceutical value. The use of transgenic plants has been increasingly tested as alternative system for obtaining biologically active human lactoferrin in plants. Precise selection of plant species, transformation techniques and expression cassettes, in addition to conduction of detailed glycosylation and immunogenicity studies, serves as basis of obtaining safe recombinant human lactoferrin in high concentrations for the use of pharmacy. On the other hand, expression of antimicrobial protein lactoferrin in plants is a promising opportunity for crop quality improvement by increasing plant disease resistance.

β-1,3-Glucanase activity was detected in extracts of different tissues of healthy mature petunia flowers except the filament. The stigma was studied further as it had the highest enzyme activity and there is a paucity of information on the occurrence of this enzyme in this tissue. Specific activity of the enzyme was found to increase within the stigmatic tissue from early development until just before anthesis. Following non-denaturing polyacrylamide gel electrophoresis at pH 8.8, extracts of dehiscent stigma seem to contain three acidic isoforms of β-1,3-glucanase. Crude extracts of stigma was passed through a pachyman affinity column. A fraction of affinity-purified active β-1,3-glucanase enzyme was found to have no antifungal activity against Trichoderma viride, Phloma clematidina and Cladosporium fulvum.

The effect of in vitro cultivation of donor shoots on subsequent morphogenesis in leaf explants of quince (Cydonia oblonga Mill.) clone BA29 was investigated. Proliferating donor shoots were cultured in ventilated or closed vessels under different photosynthetic photon flux densities (PPFD; 200 and 100 µmol m^-2 s^-1) with 0, 15, 30 g dm^-3 sucrose. Shoots grown in ventilated vessels, especially with sucrose at 15 or 30 g dm^-3, were better developed with fully expanded leaves compared to those in standard closed vessels. Leaves collected from pre-treated donor shoots were used to assess regeneration capacity. Somatic embryo production was highest in leaves harvested from shoots cultured in closed vessels with 30 g dm^-3 sucrose and in ventilated vessels with 15 and 30 g dm^-3 sucrose and under high PPFD which was, in comparison with the control treatment (closed vessel, 30 g dm^-3 sucrose and low PPFD), about 2 to 2.5 times higher. A similar response was observed for root regeneration.

Anthocyanin accumulation and expression pattern of anthocyanin biosynthesis genes were investigated in developing coleoptiles of wheat (Triticum aestivum L.). In epidermal cell layers of the growing coleoptiles of cv. Hope, anthocyanins started to accumulate between day 2 and 3 after germination, reached their maximum on day 6 and then decreased while another cultivar, Chinese Spring (CS) did not accumulate anthocyanin pigments. None of the six anthocyanin biosynthesis genes was upregulated in coleoptiles of both cvs. grown in the dark, whereas all genes were activated by light in coleoptiles of cv. Hope. Transcript levels of all the six genes were relatively low on day 2, increased from days 3 to 5 and then declined to almost non-detectable levels on day 6. In coleoptiles of CS grown in the light, the early biosynthesis genes (EBGs) were expressed, but the three late biosynthesis genes (LBGs) were not.

A rapid and efficient plant regeneration protocol for a wide range of alfalfa genotypes was developed via direct organogenesis. Through a successive excision of the newly developed apical and axillary shoots, a lot of adventitious buds were directly induced from the cotyledonary nodes when hypocotyl of explants were vertically inserted into modified Murashige and Skoog (MS) medium supplemented with 0.025 mg dm^-3 thidiazuron (TDZ) and 3 mg dm^-3 AgNO₃. When the lower part of shoots excised from explants were immersed into the liquid medium with 1.0 mg dm^-3 α-naphthaleneacetic acid (NAA) for 2 min, and then transferred to hormone free half-strength MS medium, over 83.3 % of the shoots developed roots, and all plantlets could acclimatize and establish in soil. The protocol has been successfully applied to eight genotypes, with regeneration frequencies ranging from 63.8 to 82.5 %.

The objective of this study was to determine the development of the antioxidant enzymes induced by drought stress in white clover (Trifolium repens L.) leaves. Water stress was imposed during 28 d by decreasing the daily irrigation. Leaf water potential (Φ_w) gradually decreased from -0.46 to -2.33 MPa. For the first 7 d, dry mass (DM), H₂O₂ and lipid peroxidation were not significantly affected by water deficit. From 14 d of treatment, water stress decreased dry mass and increased content of reactive oxygen species (O₂ ^.- and H₂O₂) and oxidative stress (malondialdehyde content). The ascorbate peroxidase (APOD) was activated most rapidly, already during the first week of water stress, but then its activity slowly decreased. Activation of superoxide dismutase (SOD) and catalase (CAT) by water deficit continued during the 14 d (Φ_w ≥ -1.65 MPa) and then their activities remain on the similar level. The activity of guaiacol-peroxidase (GPOD) increased mostly under progressive water stress and was correlated with increase in lipid peroxidation and growth restriction.