In vitro protocols for plantlet regeneration and medium-term genotype conservation of eight wild species of Curcuma have been optimized. Both the phenomena were genotype-dependent and influenced significantly by type and concentration of cytokinins used. In general, benzyladenine (BA) was found superior to other cytokinins tested for plantlet regeneration and γ,γ-dimethylallylaminopurine (2iP) for conservation. Number of shoots per culture ranged from 1.3 to 7.2 and conservation period from 264 to 379 d. In 30-d-old cultures, highest frequency of shoot regeneration could be obtained in C. malabarica (7.2 shoots per culture) on MS + 11.4 μM zeatin. Curcuma sp. (unidentified wild species) could be conserved for maximum period (379 d) on MS + 24.6 μM 2iP followed by C. aromatica (363 d) on MS + 22.8 μM zeatin. The tissue culture-raised plantlets were morphologically similar to their parents. The in vitro-conserved plants multiplied rapidly in tissue cultures and produced normal rhizomes upon transfer to soil in net house.

Thirteen flavonoid aglycons, contained in the strongly allelopathic epicuticular exudates of Dittrichia viscosa, were investigated for their effects on lettuce seedling radicle growth. Concerning radicle length and mass, variable results were obtained, with most of the substances having no effect, some being inhibitory and some even promotive. Shoot mass was slightly reduced in four cases. Seed germination rates, root hair and lateral root formation were not affected either. Three of the compounds (namely quercetin 3,3-dimethylether, naringenin and eriodictyol) induced a strong ageotropic response in radicle growth.

Net photosynthetic rate (P_N), transpiration rate (E), and stomatal conductance (g_s) during water stress and after rehydration were measured in Phaseolus vulgaris, Beta vulgaris, and Zea mays. Immediately before imposition of water stress by cessation of watering, plants were irrigated with water (control), 100 μM abscisic acid (ABA), and/or 10 μM N⁶-benzyladenine (BA). In all three species, application of ABA decreased g_s, E, and P_N already 1 h after application. However, during water stress g_s, E, and P_N in plants pre-treated with ABA remained higher than in plants pre-treated with water. Positive effects of ABA application were observed also after rehydration. In contrast, the effects of pre-treatment with BA were species-specific. While in bean plants BA application ameliorated negative effect of water stress, only very slight effects were observed in maize, and in sugar beet BA even aggravated the effects of water stress.

Carob tree (Cerafoma siliqua L.) micropropagated shoots were rooted on half-strength Murashige and Skoog medium, supplemented with different types and concentrations of sugars, in order to determine the effects of sugar composition and concentration on in vitro rooting and in vivo establishment of the plantlets. Among the various sugars tested, the best rooting response was obtained with 145 mM sucrose, both in terms of rooting frequency and index of rooting. The use of filter-sterilized rather that autoclaved fructose increased root number and root length. Sugar treatment during rooting slightly influenced plantlet survival and growth during acclimatization. A reduction in the glucose concentration during rooting was beneficial for plantlet acclimatization.

The in vitro cultures of apple rootstock MM 106 produced the highest fresh mass (FM) when 0.1 mM B was included in the culture medium. By increasing B concentration of the culture medium from 0.1 to 6.0 mM, FM and contents of B, P, Ca, and Mg in explants increased, whereas K, Fe, Mn, and Zn contents decreased. SPAD units of leaves characterizing chlorophyll contents declined as B concentration of the culture medium increased from 0.1 to 6.0 mM.

The effect of soil moisture on gas exchange and growth of an endangered species, Changium smyrnioides, was compared with a non-endangered species, Anthriscus sylvestris. The two species belong to the same family Umbellaceae. With the decrease of soil moisture, the net photosynthetic rate (P_N) and transpiration rate (E) decreased, while water use efficiency (WUE) increased, P_N and WUE of C. smyrnioides were lower than those of A. sylvestris, whereas E was higher than that of A. sylvestris. The biomass, leaf mass ratio (LMR) and leaf area ratio (LAR) of C. smyrnioides were lower than those of A. sylvestris. Under drought, biomass. LMR and LAR of C. smyrnioides decreased more steeply than those of A. sylvestris, whereas specific root length (SRL) of C. smyrnioides was higher, compared to that of A. sylvestris. The present study indicated that C. smyrnioides accumulated less biomass, and directed more biomass to roots than A. sylvestris.

Nodal explant cultures from field-grown five jojoba genotypes (EC 99690, EC 99692, EC 99692, EC 267779 and EC 171284; male and female plants), could be established on Murashige and Skoog (MS) medium. The nodal explants of different genotypes as well as sex elicited differential requirements of N⁶-benzyladenine (BA) for optimum shoot regeneration and medium-term conservation. Female nodal explants of EC 99692 produced maximum shoots (10 shoots per explant) followed by male of EC 171284 (9.3 shoots per explant) on MS + 10 μM BA. The pulse treatment of 50 μM indole-3-butyric acid for 20 min caused in vitro rhizogenesis in 44 - 67 % cultures of various genotypes tested. A significant difference was observed for the conservation period of male and female cultures of all the genotypes. MS + 10 μM BA supported the shoot cultures of EC 99690, EC 99691 and EC 267779 for maximum conservation period, while MS + 5 μM BA proved to be optimum for conserving the shoots of EC 99692 and EC 171284. Generally, the female shoot cultures of genotypes survived for longer period than male ones.

Direct shoot bud differentiation was achieved in leaf segments of Achras sapota cv. Cricket Ball inoculated on Schenk and Hildebrandt's medium supplemented with 5.0 μM thidiazuron and 8.88 μM benzylaminopurine. Leaves from middle part of the shoots and segments obtained from middle portion of leaf showed highest potential to regenerate shoot buds. Histological examination of developing shoot buds showed their de novo regeneration with clear vascular connection with the mother tissues.

Plant regeneration through indirect somatic embryogenesis was attempted from leaf, internode, node and shoot-tip derived callus of Leptadenia reticulata. Somatic embryos at the highest frequency was induced on Murashige and Skoog (MS) medium supplemented with 8.87 μM benzyladenine (BA) and 2.46 μM indole-3-butyric acid (IBA). From different explants, only shoot-tip and node explant derived calli induced somatic embryos. Transfer of the embryogenic callus to suspension cultures of the same concentration of growth regulators facilitated the development of embryos. Suspension cultures with reduced concentration of BA (2.22 μM) either alone or in combination with 0.49 μM IBA fostered maturation of embryos. Half-strength MS solid medium with 1.44 μM GA₃ and BA (0.22 or 0.44 μM) facilitated conversion of embryos into plantlets at higher rate compared to that on with BA alone. About 77 plantlets were recovered from 10 mg callus. Plantlets transferred to small cups and subsequently to field survived in 80 %. All the plantlets established in the field exhibited morphological characters similar to that of the mother plant.

Fatty acid ω-3 desaturase (FAD) is the key enzyme catalyzing the formation of trienoic fatty acids. We utilized an Arabidopsis FAD7 gene and the seven independent transgenic rice plants harbouring 1 to 3 copies of this gene were generated. The expression of FAD7 mRNA was different among independent transgenic lines regardless of the copy number. The total linolenic acid (18:3) contents reduced by about 7 - 32 % in transgenic rice plants but the linoleic acid (18:2) content increased accordingly. With or without wounding treatments, the jasmonate content was higher in transgenic lines than in wild-type rice plant. The transgenic lines overproducing jasmonate also showed increased expression of PR1b mRNA and allene oxide synthase inresponse to wounding.

Hypocotyl, cotyledon and cotyledonary node explants of Calendula officinalis L were cultured on Murashige and Skoog (MS) media supplemented with various concentrations of thidiazuron (TDZ), kinetin (KIN), α-naphthaleneacetic acid (NAA) and indole-3-butyric acid (IBA) to induce adventitious shoot regeneration and micropropagation. The highest frequency of adventitious shoot regeneration was achieved from hypocotyl and cotyledon explants on MS media supplemented with 0.75 mg dm^-3 TDZ and either 0.25 or 0.50 mg dm^-3 IBA. Efficient in vitro clonal propagation was also induced from cotyledonary nodes on a range of media supplemented with 0.75 mg dm^-3 TDZ and 0.05 mg dm^-3 NAA or 2 mg dm^-3 KIN and 1 mg dm^-3 NAA. Regenerated shoots were excised and rooted in MS medium supplemented with 1 mg dm^-3 NAA. The rooted plantlets were finally transferred to pots.

The effects of drought and rehydration on tea seedlings were significant. After five days of drought imposition the contents of chlorophylls, carotenoids, ascorbate and glutathione, and activities of guaiacol peroxidase and glutathione reductase decreased. Simultaneously, contents of proline, H₂O₂ and superoxide anion, lipid peroxidation and activities of catalase and superoxide dismutase increased. These parameters recovered to different degrees during subsequent rehydration.

Enzyme changes in non-rooted (treated with Fe-EDTA) and rooted (treated with Fe-EDDHA) stems of rootstock GF-677 (Prunus amygdalus×P. persica) during adventitious root formation in vitro have been recorded. The first roots appeared approximately after 12 d on the rooting medium. By contrast to non-rooted stems, rooted stems showed a maximum of soluble peroxidase activity on the 9^th day, of ionically bound peroxidase to cell wall on the 6^th and 12^th day and of catalase on the 6^th and the 15^th day. A time course study of changes of soluble peroxidases isoenzymes showed that there was a band visible only in the rooted stems and also a new band appeared three days before the emergence of roots.

Thermotolerance of pearl millet (Pennisetum glaucum cv. ICMV-94133) and maize (Zea mays cv. Golden) was assessed at germination and vegetative stage. Final percentage of germinated seeds and rate of germination (number of days to 50 % germination) decreased due to high temperature (45 °C) similarly in the both species. In contrast, at the vegetative stage, high temperature (38/27 °C) caused a significant reduction in shoot dry mass of maize, whereas this attribute remained almost unchanged in pearl millet. Relative growth rate and net assimilation rate (NAR) increased significantly in pearl millet due to high temperature, but in contrast, in maize NAR was slightly reduced. Concentrations of N, P, and K in the shoots of both species increased at high temperature, but N accumulation was more pronounced in pearl millet than in maize. High temperature caused a marked increase in both shoot and root Ca²⁺ concentration in maize, but it did not affect that of pearl millet. S concentration in the shoots of maize decreased significantly due to high temperature, whereas that in pearl millet remained unaffected. Shoot Na⁺ concentration of both species was not significantly affected by high temperature. High temperature caused a significant increase in uptake of N, P, and K⁺ in pearl millet, but the uptake of Ca²⁺, Mg²⁺, Na⁺ and S remained unaffected in this species. In contrast, in maize, a significant increase in uptake of K⁺ and Ca²⁺, and a decrease in uptake of N, S, Mg²⁺, and Na⁺ were found at high temperature. Overall, maize showed lower tolerance to high temperature compared with pearl millet.

Fatty acid content and composition of chloroplast membranes, ethylene production associated with thylakoid lipids degradation as well as photosynthetic electron transport involving photosystems 1 and 2 were used to determine the effects of increasing Cd concentrations in the growth medium [0, 14, 28, and 42 mg (Cd) kg^-1(sand)] on the photosynthetic performance of barley plants (H. vulgare L., cv. CE9704). High concentrations of Cd triggered serious disturbances of the chloroplast membranes. Ethylene production increased whereas a drop of 18:3 fatty acid content occurred, indicating that Cd mediates lipid peroxidation in the thylakoids. The enhanced ethylene production could be used as an early indicator of Cd-induced membrane degradation, yet at very high concentration (42 mg kg^-1) Cd decreased ethylene production.

Following 16, 40 and 64 h exposure to 0.33 M NaCl given after 8 h water imbibition, lentil seeds showed a gradual decrease of germination upon their transfer to water. These salt related changes were accompanied by modifications in the protein patterns of embryo axes as revealed by two-dimensional electrophoresis separation and by the computer image analysis of protein spots. In comparison with 8 h water imbibed seeds, prominent proteins comprised between the 5.1 - 7.6 pH isoelectric point in the first dimension and 75 - 50 kDa molecular mass in the second dimension showed a significant increase in their abundance as salt exposure increased. On transfer to water to complete germination, the content of many of these proteins decreased at 24h in 2 - 3 cm length embryo axes in comparison with the corresponding embryo axes of seeds continuously imbibed in water for 24 h. Some groups of proteins ranging between 15.5 - 17.3 kDa, already present after 8 h water imbibition, were not detectable after 24 h but were expressed in seeds exposed to NaCl and transferred to water for 24 h. Up- and down-regulated proteins in lentil embryo axes, imbibed under non-lethal salt stress conditions, have been tentatively identified by comparison with the protein map of germinating seeds of the model plant Arabidopsis.

In vitro root culture of yellow wort (Blackstonia perfoliata (L.) Huds.) was initiated on Murashige and Skoog (MS) medium. In the presence of benzylaminopurine (BAP) numerous adventitious buds formed, which developed into shoots. Presence of indole-3-butyric acid (IBA) in media significantly decreased number of buds, but increased development of lateral roots. On hormone-free medium shoots successfully rooted and developed flowers and viable seeds that formed another generation. Shoot cultures of B. perfoliata inoculated with suspension of Agrobacterium rhizogenes strain A4M70GUS developed hairy roots at 3 weeks and they were cultured on hormone-free MS medium. Spontaneous shoot regeneration occurred in 3 clones.

Changes in the proteins, chlorophyll, virus content and activity of key enzymes of viral RNA biosynthesis were investigated in the light- and dark-green regions of tobacco leaves systemically infected with tobacco mosaic virus. The protein content was increased to 118 % in the dark-green islands in contrast to 60 % in the light-green regions when compared with the control healthy leaves. The comparative analysis of soluble proteins from healthy and light- or dark-green regions of leaves by means of SDS-PAGE revealed that the main soluble proteins are equal in pattern but differ in quantity. The contents of chlorophylls did not differ from healthy tissues in the dark-green islands but were considerably lower in the light-green regions. The content of virus in light-green tissues was about 10 times higher than in the dark-green islands. The activities of key enzymes of oxidative pentosephosphate cycle -- glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase -- did not differ from healthy tissues in the dark-green islands but were considerably higher in the light-green tissues when compared with healthy control. Similar relationships were observed for ribonuclease, phosphomonoesterase and phosphodiesterase activities. The biosynthesis of viral RNA in the dark-green islands is probably restricted by the steady (or reduced) activities of key enzymes of these metabolic pathways.

A highly reproducible system for efficient somatic embryogenesis was developed to regenerate plantlets from cotton (Gossypium hirsutum L.) cultivars (Nazilli M-503 and Nazilli 143). Shoot apices, hypocotyls and nodes of 10-d-old seedlings were used as explants. High frequency (100 %) embryogenic calli was initiated from all tested explants on Murashige and Skoog (1962) (MS) media supplemented with 1 g dm^-3 polyvinylpyrrolidone (PVP), 1 mg dm^-3 6-benzylaminopurine (BAP), 0.5 mg dm^-3 kinetin for Nazilli M-503 and 1 g dm^-3 PVP, 2 mg dm^-3 BAP, 0.5 mg dm^-3 kinetin for Nazilli-143. Globular stage somatic embryos were produced 4 months after transfer to hormone-free MS medium supplemented with 1 g dm^-3 PVP. Subsequent subculture of globular embryos every 3 weeks on hormone-free MS medium led to the development of torpedo and cotyledonary stage embryos with the frequency of 75 and 83.2 % from hypocotyl explants of Nazilli M-503 and Nazilli-143, respectively. Afterwards, mature somatic embryos were isolated and cultured on hormone-free MS medium for germination and development into plantlets. The highest germination frequency (42.9 %) for Nazilli M-503 somatic embryos were obtained on hormone-free MS medium after 5 months with hypocotyl explants, whereas germination frequencies of Nazilli-143 embryos from hypocotyl, node and apex explants varied between 22 - 30 %.

Two-days-old in vitro grown protonemata of Funaria hygrometrica Hedw. were treated with a mixture PbCl₂ (4 μM Pb²⁺) and CaCl₂ (16 μM Ca²⁺) (Ca+Pb) for 48 h. The results were compared with the control: distilled water (H₂O) and the solution of PbCl₂ (4 μM Pb²⁺) (Pb). Protonemata treated with Ca+Pb were longer and contained more cells than those treated with Pb. Moreover, a lower number of cells showed apical cell deformations typical for lead toxicity: swollen tips and wall thickenings at the apex. If deformations were present they were not as extended as in Pb. In comparison with the control, however, protonemata treated with Ca+Pb were shorter, contained a lower number of cells and some apical cells in this material were altered. It can be concluded that the presence of calcium partially neutralised toxic effects of lead in Funaria hygrometrica protonemata cells.

The aim of this research was to carry out a critical study of the method of obtaining size equivalence between non-symbiotic alfalfa and alfalfa associated with Glomus and/or Rhizobium by applying fixed addition rates of nutrients to the non-symbiotic controls. The experimental design included three nutrient response curves in which the levels of added phosphorus and/or nitrogen were constant during the whole plant growth process: 1) a phosphorus response curve, in order to compare the growth of double symbiotic plants with that of only-Rhizobium inoculated ones; 2) a nitrogen response curve, that consisted of a comparison between the growth of double symbiotic alfalfa and four treatments associated only with Glomus; 3) a phosphorus and nitrogen response curve, to compare the growth of non-inoculated alfalfa with that of double symbiotic plants. Although similar size was achieved among some treatments at harvest, shoot growth over time and nutrient concentrations in tissues differed, indicating that growth equivalence did not mean functional equivalence. A second experimental design was performed taking into account the establishment of microsymbionts for determining the adequate moment to add supplemental phosphorus and/or nitrogen. It included four treatments: a) double symbiotic plants (MR); b) plants inoculated with Rhizobium only (R); c) plants inoculated with Glomus only (M), and d) non-inoculated plants (N). Great similarity in terms of plant growth and nutrient contents in tissues were obtained. Moreover, symbiotic plants were able to produce similar dry matter than non-symbiotic ones under P and N limitations.

Six pea (Pisum sativum L.) cultivars (Adept, Komet, Lantra, Olivin, Oskar, Tyrkys) were transformed via Agrobacterium tumefaciens strain EHA105 with pBIN19 plasmid carrying reporter uidA (β-glucuronidase, GUS, containing potato ST-LS1 intron) gene under the CaMV 35S promoter, and selectable marker gene nptII (neomycin phosphotransferase II) under the nos promoter. Two regeneration systems were used: continual shoot proliferation from axillary buds of cotyledonary node in vitro, and in vivo plant regeneration from imbibed germinating seed with removed testa and one cotyledon. The penetration of Agrobacterium into explants during co-cultivation was supported by sonication or vacuum infiltration treatment. The selection of putative transformants in both regeneration systems carried out on media with 100 mg dm^-3 kanamycin. The presence of introduced genes was verified histochemically (GUS assay) and by means of PCR and Southern blot analysis in T₀ putative transformants and their seed progenies (T₁ to T₃ generations). Both methods, but largely in vivo approach showed to be genotype independent, resulting in efficient and reliable transformation system for pea. The in vivo approach has in addition also benefit of time and money saving, since transgenic plants are obtained in much shorter time. All tested T₀ - T₃ plants were morphologically normal and fertile.

Tobacco plants (Nicotiana tabacum L. cv. Sevilla) were grown under controlled conditions. The leaf content of Ca²⁺, Mg²⁺ and K⁺, and the activity of the pyruvate kinase were analyzed. The increased application of Ca²⁺ diminished the content of K⁺ and Mg²⁺ in leaves, and decreased the activity of pyruvate kinase. Taking into account these results, we suggest the pyruvate kinase activity as an bioindicator of the contents of the Ca²⁺, Mg²⁺ and K⁺.

Callus cells of potato (Solanum tuberosum L.) cv. Désirée were exposed to various subzero temperatures and examined for the freezing damage. In the cells subjected to -3 °C, plasma membranes appeared to be intact, while tonoplast seemed to be damaged and organelles to be swollen. After freezing at -6 °C, the damage became severe and plasma membranes were ruptured. After exposure to -10 °C, the damage was so severe that the cell organelles could not be recognised and cytoplasm became fragmented.

The regulation of proline accumulation in polyethylene glycol (PEG, -1.5 MPa) treated rice leaves was investigated. PEG treatment resulted in a decrease in relative water content, indicating that PEG treatment caused water stress in rice leaves. Proline accumulation caused by PEG was related to protein hydrolysis, an increase in ornithine-δ-amino- transferase activity, an increase in the content of ammonia, and an increase in the contents of the precursors of proline biosynthesis, glutamic acid, ornithine, and arginine. Results also show that abscisic acid accumulation is not required for proline accumulation in PEG-treated rice leaves.

The effects of aluminum on lipid peroxidation and activities of antioxidative enzymes were investigated in detached rice leaves treated with 0 to 5 mM AlCl₃ at pH 4.0 in the light. AlCl₃ enhanced the content of malondialdehyde but not the content of H₂O₂. Superoxide dismutase activity was reduced by AlCl₃, while catalase and glutathione reductase activities were increased. Peroxidase and ascorbate peroxidase activities were increased only after prolonged treatment, when toxicity occurred. The results give evidence that Al treatment caused oxidative stress and in turn, it caused lipid peroxidation.