Oncidium cultivars gave different embryogenic responses of leaf explants when affected by auxins (2,4-D, IAA, IBA and NAA), cytokinins (2iP, BA, kinetin, TDZ and zeatin), sucrose, NaH₂PO₄, casein hydrolysate, peptone, and glutamine. The best embryogenic responses of cv. Sweet Sugar were at 20 g dm^-3 sucrose, 85 mg dm^-3 NaH₂PO₄ and 3 mg dm^-3 kinetin, respectively. The development of somatic embryos on leaf explants of cv. Sweet Sugar was delayed for about 10 - 20 d in comparison with cv. Gower Ramsey. On growth regulator-free medium, about 40 % of leaf derived embryos of cv. Gower Ramsey were fused together in their basal parts and so called multiple-state embryos. However, under the same condition, the embryos of cv. Sweet Sugar were all in multiple-state form.

The in vitro rooting of myrtle (Myrtus communis L.) plantlets was performed in containers with gas permeable (V) and non-permeable (C) closures characterized by a different number of gas exchanges (1.4 and 0.3 h^{- 1}, respectively). The rooting was induced on Perlite, soaked with half strength Murashige and Skoog (MS) medium with 0.5 mg dm^-3 IBA, either with and without 15 g dm^-3 of sucrose. During the rooting phase, it was demonstrated that C cultures without sucrose (C-) negatively affect the growth of myrtle plantlets. The net photosynthetic rate and the starch content showed the lowest values in C cultures with and without sucrose (C+ and C-) while chlorophyll a content did not vary among treatments, therefore it could not be considered an indicative parameter to evaluate the autotrophic metabolism in myrtle plantlets. Electron microscopy and image analysis were employed to evaluate the leaf ultrastructure at three sample dates. Plantlet rooted in vented vessels with and without sucrose (V+ and V-) showed chloroplasts with numerous starch inclusions, while several osmiophilic plastoglobules (frequently related with leaf senescence) were found in chloroplast of leaf cells of C- myrtle plantlets.

Late blight of potato, caused by Phytophthora infestans was studied by using a resistant clone of potato on one side and a susceptible clone on the other side. A gene coding putatively for an α-galactosidase has been isolated by mRNA reverse transcription polymerase chain reaction differential display and was shown to be differentially expressed between the resistant and the susceptible clone. α-Galactosidases catalyse the hydrolysis of α-1,6 linked α-galactose residues from oligosaccharides and it could be shown in the present work that raffinose content decreases at 30 h after infection by P. infestans in the resistant clone.

A reproducible protocol has been developed for high frequency plant regeneration from immature embryos of Argyrolobium roseum Jaub & Spach, an important medicinal legume. Green nodular calli were initiated from immature embryos excised from 10-d-old pods in 70 % of cultures within 3 weeks when grown on Murashige and Skoog (MS) medium supplemented with 0.5 mg dm^-3 benzylaminopurine (BAP) + 0.25 mg dm^-3 indole-3-acetic acid (IAA). Subsequent transfer of 5 mm² callus pieces to MS medium supplemented with BAP (0.5 mg dm^-3) alone or in combination with IAA (0.25 mg dm^-3) facilitated regeneration of multiple shoots. Organogenic calli bearing multiple shoots when transferred to MS medium supplemented with BAP (0.5 mg dm^-3) + IAA (0.25 mg dm^-3) supported rapid shoot elongation. Shoot propagules subcultured to Gamborg's medium (B5) with 0.5 mg dm^-3 indole-3-butyric acid (IBA) rooted with 80 % frequency and developed into phenotypically normal plants. Plantlets were successfully acclimatized in a sterile mixture of sand and garden soil (1:1) under greenhouse and thereafter transferred to field beds.

The effects of NaCl on growth, contents of proteins and proline, and activities of catalase, peroxidase and polyphenol oxidase were investigated in seedlings and calli of Trigonella foenum-graecum L. and T. aphanoneura Rech. f. Seeds and hypocotyl explants were cultured on Murashige and Skoog medium supplemented with 0, 50, 100, 150 and 200 mM NaCl. Seed germination and the fresh and dry mass of the seedlings decreased significantly under salinity. In both species significant increases in protein content of seedlings over that of control were observed at 150 and 200 mM NaCl. Protein content in calli decreased at 200 mM NaCl over that of control. Protein content was higher in seedlings than in calli at all NaCl concentrations. Conversely, proline content was lower in seedlings than in calli at all the tested NaCl concentrations. NaCl caused changes in the activities of peroxidase, catalase and polyphenol oxidase in seedlings and calli.

The inoculation of the seedling roots of the resistant (Bousthami Noir) and susceptible (Jihel) date palm (Phoenix dactylifera) cultivars by Fusarium oxysporum f. sp. albedinis induced an increase in phenylalanine ammonia-lyase (PAL) activity. The response of the PAL activity in the resistant cultivar was faster and higher than in the susceptible one. However, the elicitation of the seedlings with the hyphal wall elicitor (HWE) of the pathogen induced identical PAL activity in both cultivars. In the resistant cultivar, the the PAL activity elicited with the HWE was not influenced by the addition of the fungal culture filtrate (FCF) whereas it was suppressed in the susceptible cultivar. This FCF suppressor effect was dose-dependent, not influenced by sodium periodate, whereas it was strongly reduced by the heat (121 °C for 45 min) and pronase E. These results show that differential induction of the defence mechanisms in both cultivars was not related to differences in the induction of the PAL activity, but to the suppression of its elicitation in the susceptible cultivar.

The aim of this study was to investigate the protein alterations in the transgenic kiwifruit (Actinidia deliciosa) overexpressing a transcription factor gene, OSH1. Although transgenic plant with introduced OSH1 indicates suppression of gibberellin (GA)-20 oxidase activity, application of GA to transgenic kiwifruit could not completely recover plant morphology and protein profiles. Eleven proteins decreased in the transgenic kiwifruit detected by two-dimensional polyacrylamide gel electrophoresis showed homologies to kiwifruit hypothetical protein, osmotin I and photosynthesis related protein. These results suggest that introduction of an OSH1 into kiwifruit caused wide-range alterations at protein level and alterations of protein accumulation should be considered to evaluate the substantial equivalence of plants transformed by a transcription factor.

To determine whether the major influence of high salinity is caused by the osmotic component or by salinity-induced specific ion toxicity, we compared the effects of mannitol, sorbitol, NaCl and KCl (all in concentratuions corresponded to osmotic potential -1.0 MPa) on the antioxidant and anatomical responses of the apple rootstock MM 106 explants grown in the Murashige and Skoog (MS) medium. All the compounds had a significant influence on explant's mineral composition and reduced the leaf water content, whereas mannitol and salts decreased chlorophyll (Chl) content and increased proline content. Superoxide dismutase (SOD), peroxidase (POD) and non-enzymatic antioxidant activities as well as H₂O₂ content were increased in the leaves and stems. In addition, in the leaves of explants exposed to NaCl an additional Mn-SOD isoform was revealed, while specific POD isoforms were detected in the leaves and stems treated with NaCl or KCl. However, catalase activity was depressed in the salt-treated leaves. At the ultrastructural level, the NaCl-treated leaves had the thickest lamina, due to an extensive increase of the size of epidermal and mesophyll cells. Also, an increase of the relative volume of the intercellular spaces in response to NaCl was observed. The results suggest that Na accumulation is the first candidate for the distinct antioxidant and anatomical responses between saline and osmotically generated stress in the MM 106 explants.

The effect of arsenic (32 - 96 µM) on the phosphorus content and Chl fluorescence was studied in soybean (Glycine max Merril) grown in the nutrient solution with and without phosphorus. The increased concentration of As led to the decrease in P content in plant organs. Parameters of Chl fluorescence of soybean leaves in the presence of these As concentrations did not show significant changes.

The biological activity of cell wall-derived galactoglucomannan oligosaccharides (GGMOs) was dependent on their chemical structure. Galactosyl side chains linked to the glucomanno-core influenced their inhibition of elongation growth of pea (Pisum sativum L. cv. Tyrkys) stem segments induced by 2,4-dichlorophenoxyacetic acid (2,4-D). Reduction of the number of galactosyl side chains in GGMOs caused stimulation of the endogenous growth. Modification on the glucomanno-reducing end did not affect significantly the activity of these oligosaccharides. GGMOs inhibited also the elongation induced by indole-3-acetic acid (IAA) and gibberellic acid (GA₃). In the presence of IAA the elongation growth was inhibited to 20 - 35 % after 24 h of incubation depending on GGMOs concentrations (1 μM, 10 nM, 0.1 nM), similarly as in the presence of 2,4-D, which confirms the hypothesis of GGMOs antiauxin properties. The elongation induced by GA₃ was inhibited to 25 - 60 %, however, the time course of inhibition was different compared with IAA and 2,4-D. The highest inhibition was determined already after 6 h of incubation with a significant decrease after this time. The results indicated a competition between GGMOs and growth regulators.

The aim of the present work was to evaluate oxidative stress and plant antioxidant system of three contrasting bean (Phaseolus vulgaris L.) genotypes in the response to drought. Drought was imposed 14 d after emergence, by withholding water, until leaf relative water content reached 65 %. Water stress increased lipid peroxidation (LPO), membrane injury index, H₂O₂ and OH^⋅ production in leaves of stressed plants. Activities of the antioxidative enzymes superoxide dismutase (SOD) and ascorbate peroxidase (APOX) increased significantly under water stress in all the studied cultivars, while catalase (CAT) increased in cvs. Plovdiv 10 and Prelom, but decreased in cv. Dobrudjanski ran. Furthermore cv. Plovdiv 10 which had the highest APOX and CAT activities also showed the lowest increase in H₂O₂ and OH^⋅ production and LPO while cv. Dobrudjanski ran showed the lowest increases (and often the lowest values) in the antioxidant enzyme activities and the highest increases of H₂O₂ and OH^⋅ production, and LPO. On the basis of the data obtained we could specify cv. Plovdiv 10 and cv. Prelom as drought tolerant and cv. Dobrudjanski ran as a drought sensitive.

Flow cytometric analysis of ten bulked seeds is proposed to quantify particular embryo ploidy classes in Hieracium. The method is recommended 1) for the detection and quantification of residual sexuality in facultative apomicts, which can generate progeny from heteroploid crosses, 2) for the quantitative screening of pollen donors with different ploidy levels, based on the fertilization success of the maternal plant, and 3) for the screening of parents producing a high proportion of polyhaploids.

Partial cDNAs sequences for arginine decarboxylase (Pvadc), S-adenosylmethionine decarboxylase (Pvsamdc) and spermidine synthase (Pvspds) were isolated from the bean Phaseolus vulgaris using primers designed from conserved regions of enzymes belonging to plant species. Sequence analysis showed that the Pvadc, Pvsamdc and Pvspds genes were most closely related to the orthologous genes from Glycine max, Phaseolus lunatus and Pisum sativum, respectively. The expression patterns of the genes, together with that of ornithine decarboxylase (Pvodc), were analysed in young and mature leaves, stems, roots, root tips, petals, stigma, ovaries, filaments and anthers of bean plants. Pvsamdc was found to be expressed at similar levels in all tissues. The other transcripts showed tissue specific expression. Pvadc was barely expressed in petals and not at all in roots tips, Pvspds was mainly expressed in roots, stigma and filaments, and Pvodc was detected only in roots.

A regulatory hrpL non-virulent mutant of Erwinia amylovora is effective in controlling fire blight disease when inoculated on apple seedlings simultaneously with the pathogenic parental strain. Mechanisms involved in this protective effect were investigated. The use of two marker genes, uidA and lacZ, expressed in the hrpL mutant and the pathogenic strain, respectively, allowed to localize simultaneously the two inoculated strains in plant tissue. An anti-β-glucuronidase antibody was also used to detect the hrpL mutant. Both techniques indicated that the two strains localized mainly in separate areas of the leaf tissue. In addition, leaves infiltrated with the hrpL mutant exhibited a significant increase in peroxidase activity in contrast to a hrp secretion mutant known to be less effective in the protection. It is suggested that protection obtained with the hrpL mutant relies on the physical separation between the mutant and the parental strain after co-inoculation and the rapid and sustained activation of plant defense mechanisms in reactive tissue, i.e. not invaded by the virulent strain.

An efficient and rapid regeneration protocol was developed using shoot apices from germinating seedlings of two cultivars of sorghum, SPV-462 and M35-1, as explants. A vertical slit given from the base of each dissected apex enhanced the efficiency of callusing response by two fold. MS medium containing 0.5 mg dm^-3 each of 2,4-D and kinetin was most effective in producing friable and embryogenic calli. Scanning electron microscopy of these calli detected somatic embryogenesis. Calli thus induced gave rise to approximately 42 green shoots per callus in both the genotypes when transferred to regeneration medium containing 1.5 mg dm^-3 kinetin.

The pattern and expression level of β-glucuronidase (gus) reporter gene regulated by six heterologous promoters were studied in transgenic Populus tremula × P. alba plants obtained by Agrobacterium-mediated transformation. Binary vector constructs used contained the following promoter sequences: the CaMV35S from cauliflower mosaic virus; its duplicated version fused to the enhancer sequence from alfalfa mosaic virus; CsVMV from cassava vein mosaic virus; ubiquitin 3 from Arabidopsis thaliana (UBQ3); S-adenosyl-L-methionine synthetase (Sam-s) from soybean; and the rolA from Agrobacterium rhizogenes. Histochemical staining of root, stem and leaf tissues showed phloem and xylem-specific gus expression under rolA promoter, and constitutive expression with the other putative constitutive promoters. Quantitative GUS expression of 10 - 15 independently transformed in vitro grown plants, containing each promoter, was determined by fluorimetric GUS assays. The UBQ3-gus fusion induced the highest average expression level, although an extensive variation in expression levels was observed between independent transgenic lines for all the constructs tested.

Shoot apical meristem-derived calli were transformed with a hLF cDNA in an attempt to produce human lactoferrin (hLF) in transgenic cell suspension cultures of sweet potato [Ipomoea batatas (L.) Lam.]. Calli were bombarded with tungsten particles coated with the binary vector pLSM1 containing a hLF cDNA under the control of the 35S promoter and the neomycin phosphotransferase gene as a selection marker. Calli were then transferred to Murashige and Skoog (MS) medium supplemented with 4.52 µM 2,4-dichlorophenoxyacetic acid (2,4-D) and 100 mg dm^-3 kanamycin. Kanamycin-resistant calli were selected at four-week intervals and subcultured. Cell suspension cultures were established in liquid MS medium with 4.52 µM 2,4-D. Southern and Northern blot analyses confirmed that hLF cDNA was incorporated into the plant genome and was properly expressed in the cells. ELISA analysis showed that transgenic cells produced hLF up to 3.2 µg mg^-1 (total protein).

In the present study, two polymerase chain reaction (PCR)-based methods namely, randomly amplified polymophic DNA (RAPD) and amplification fragment length polymorphism (AFLP) were employed to assess genetic variations, which may appeared, in tissue culture-derived date palm (Phoenix dactylifera) offshoots. Analysis of RAPD banding patterns generated by PCR amplification using 37 random primers gave no evidences for somaclonal variations and the percentage of polymorphic bands in a total of 259 scored bands was zero. Meanwhile, analysis of AFLP banding patterns generated using 13 primer combinations pointed to minor genetic variations in the AFLP banding patterns. The percentage of genetic variations (polymorphism) in tissue culture-derived date palm offshoots belonging to cultivars Sakkoty, Gandila and Bertamoda was 2.6, 0.79 and 1 %, respectively, as revealed by AFLP analysis. The low percentage of genetic variations confirms the genetic stability of tissue culture-derived dry date palm cultivars.

This report describes in vitro shoot induction and plant regeneration from mature nodal explants of Vitex trifolia L. on Murashige and Skoog (MS) medium fortified with benzylaminopurine (BAP), kinetin (KN), thidiazuron (TDZ), adenine (ADE), and 2-isopentenyladenine (2-iP) (0.25 - 10.0 μM). Multiple shoots differentiated directly without callus mediation within 3 weeks when explants were cultured on medium supplemented with cytokinins. The maximum number of shoots (9 shoots per explant) was developed on a medium supplemented with 5.0 μM BAP. Shoot cultures was established repeatedly subculturing the original nodal explant on the same medium. Rooting of shoots was achieved on half strength MS medium supplemented with 0.5 μM naphthaleneacetic acid (NAA). Rooted plantlets transferred to pots containing autoclaved soil and vermiculite mixture (1:1) showed 90 % survival when transferred to outdoor.

We have developed three protocols for the rapid micropropagation of Ruscus aculeatus. The primary explants utilised were immature embryos, aerial buds excised from rhizomes and shoot buds regenerated from organogenic calli. In order to increase the plant regeneration from the primary explants, we used organogenic calli from cladode, stem and rhizome segments. We tested more than 20 culture media for callus induction and shoot regeneration and the best results were obtained when rhizome segments were cultured on Murashige and Skoog medium supplemented with 0.5 mg dm^-3 2,4-dichlorophenoxyacetic acid and 1 mg dm^-3 kinetin.

Hypocotyls of cotton (Gossypium hirsutum L.) cultivars cv. YZ-1, Coker 312 and Coker 201 were inoculated on Murashige and Skoog callus induction medium. YZ-1 exhibited a very high regeneration potential, with 81.9 % of the explants inoculated differentiated into embryogenic callus within 8-10 weeks. During the process of callus maintenance (subculture for 1 to 3 years), the total embryos number in Coker 312 and Coker 201 calli dropped sharply, and the percentage of embryo germination decreased. On the contrary, the callus of YZ-1 consistently maintains a high frequency of plant regeneration after long-time subculture. Transgenic kanamycin-resistant calli of Coker 201 partially lost the ability of somatic embryogenesis and plant regeneration. The stress produced by the transformation procedure slightly affected somatic embryogenesis and plant regeneration of YZ-1, which showed minimum loss of plant regeneration ability.

Alfalfa (Medicago sativa L. cv. Siwa 1) seeds were germinated in polyethylene glycol (PEG 4000) of different concentrations and with or without putrescine. The decrease in water potential of the PEG solution reduced germination rate, germination percentage, and growth criteria (e.g., hypocotyl length, fresh and dry masses of shoot and root), while the root length was increased. The decrease in water potential also reduced the contents of total soluble and reducing sugars, and proteins, and activities of α-and β-amylases and invertase, while increased protease activity. Putrescine treatment improved germination and all growth criteria and increased the activity of the hydrolytic enzymes except protease. In a pot experiment, drought stress was imposed by decreasing the soil moisture. Growth criteria, contents of proteins, chlorophyll a, b and carotenoids, as well as Hill reaction activity decreased while the hydrolytic enzyme activity and total soluble and reducing sugar contents increased under drought stress. Putrescine treatment decreased the activity of the hydrolytic enzymes and increased the polysaccharide, protein and photosynthetic pigment contents, and Hill reaction activity.

Effect of alginate matrix composition on regrowth performance of encapsulated microcuttings of hybrid aspen (Populus tremula L. × P. tremuloides Mincx.) was studied. Both high regrowth frequency and viability of explants were registered in all encapsulation mixtures tested. Some ingredients of the matrix (nutrient medium salts, sugars, growth regulators) significantly affected the initial development of the microcuttings. Sucrose appeared to play an important role in the starting stage of the regrowth event.

The effects of carbon sources (sucrose, glucose, fructose and mannitol) and auxins [indolebutyric acid (IBA) and α-naphthaleneacetic acid (NAA)] on in vitro propagation of banana (Musa spp. AAA) were studied. Over all carbon sources tested, sucrose induced highest frequency of shoot proliferation. Optimal shoot proliferation rates were achieved on the Murashige and Skoog (MS) medium supplemented with sucrose and glucose combination (1:1) at the concentration of 30 g dm^-3. Similarly, higher frequency of root induction was obtained at IBA and NAA combination (1:1; concentration of 2 mg dm^-3) than at other concentrations of IBA or NAA alone or their combinations.

Random amplified polymorphic DNA (RAPD) markers were used to assess the genetic diversity of 14 individuals belonging to 7 populations of Coscinium fenestratum (Gaertn.) Colebr. (Menispermaceae). 18 decamer primers used for the analysis generated 99 scorable bands of which 79 were found to be polymorphic. Coefficient of similarity ranged from 0.6604 to 0.9809. Variation within population was slightly higher than between populations. Similarity between individuals within and between populations was found. Dendrogram was obtained by using unwieghed pair-group method analysis (UPGMA). Distinct accession also exhibited higher percentage of medicinally active compound.

Leaf explants of Phalaenopsis amabilis var. formosa formed clusters of somatic embryos directly from epidermal cells without an intervening callus within 20 - 30 d when cultured on 1/2-strength modified Murashige and Skoog medium supplemented with 0.1, 1 and 3 mg dm^-3 TDZ. Repetitive production of embryos involved secondary embryogenesis could be obtained by culturing segments of embryogenic masses on TDZ-containing media. Plantlet conversion from embryos was successfully achieved on regulator-free growth medium.

A rapid and efficient in vitro plant regeneration method was developed for Aristolochia indica. Multiple shoot formation was induced from shoot tip and nodal explants on Murashige and Skoog (MS) medium with 1 - 6 mg dm^-3 2-isopentenyl-adenine (2-iP) or 1 - 4 mg dm^-3 6-benzyladenine (BA). Maximum number of shoots were induced with 5 mg dm^-3 2-iP alone (about 12 - 14 shoots). Shoot differentiation occurred directly from the leaf bases as well as from the internodes when cultured on 1 - 4 mg dm^-3 BA and 0.8 - 2 mg dm^-3 α-naphthaleneacetic acid (NAA) containing medium. Regeneration from the callus occurred when the calli initiated on MS medium containing 0.6 - 4 mg dm^-3 NAA in combination with 0.8 - 3 mg dm^-3 BA were transferred to 1 - 6 mg dm^-3 BA alone containing medium. Elongated shoots were separated and rooted in MS medium containing 1 mg dm^-3 indole-3-butyric acid. These were then transferred to soil after gradual acclimatization.