In four genotypes of chickpea (Cicer arietinum L.) BG 362, BG 372, BG 329 and C235 the relationship between somatic embryogenesis of leaf explants and ethylene and methane evolution was studied. In BG 362, which was more embryogenic than other genotypes, a higher ethylene:methane ratio of 5.8:1 at day one after inoculation in the induction medium and a lower ethylene:methane ratio of 2.89:1 in the maturation medium was found. On the contrary, in BG 372 with the least embryogenic potential, a lower ethylene:methane ratio of 1.7:1 in the induction medium and a higher ethylene:methane ratio of 4:1 in the maturation medium was found. Thus, these ratios in induction and maturation stages seems to be markers for embryogenesis in leaf explants of chickpea.

Plants of bean (Vicia faba L. cv. Calvor 103) were salt-stressed with NaCl and CaCl₂ in concentrations inducing soil osmotic potentials (ψ_soil) from 0 to -1.2 MPa and were sprayed with proline (8.7 µM) and glycinebetaine (8.5 µM) solutions. Bean plants respond to increasing soil salinity by decreased leaf relative water content and osmotic potential. Salinity decreased the contents of dry mass, chlorophyll, soluble and hydrolysable sugars, soluble proteins and enhanced content of total free amino acids, Na⁺, Ca²⁺ and Cl^-. The ratio of K⁺/Na⁺ was decreased on salinization. The membranes of leaf discs from salt-stressed plants appeared to be less stable under heat stress (51 °C) than that of unstressed plants. The reverse was true for discs placed under dehydration stress (40 % polyethylene glycol 6000). Proline and glycinebetaine application reduced membrane injury, improved K⁺ uptake and growth. Also both solutes increased chlorophyll contents.

An improved version of a simple histochemical test for the in situ assaying the production of hydrogen peroxide in living plant tissue was demonstrated. The test solution containing 50 mM KI in a 4 % potato starch solution was directly applied to the fresh cut surface of the tissue to be tested. Incorporation of an enhancer potassium permanganate (1 % final concentration) into the test reagent resulted in a ten times greater hydrogen peroxide mediated oxidation of iodide ions to iodine, especially in the case when, e.g. suboptimal concentration of H₂O₂ is present or endogenous catalase decomposes the H₂O₂ in tissue as quickly as it is evolved. Subsequently, iodine is complexed by the starch to form a coloured product. H₂O₂ production by wound-induced oxidative burst or lignification can be easily discriminated due to the dual colour response.

Chlorophyll (Chl) a and b content, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) content and activity, and electron transport rate were measured in flag leaves of wheat genotypes Uniculm and Kalyansona, grown at suboptimal and optimal supply of nitrogen. The Chl content, RuBPCO activity, and electron transport rate were decreased due to suboptimal nitrogen supply only in Kalyansona. There was no change in the ratio of RuBPCO and photosystem 2 (PS2) activity at various stages which suggests that there was no alteration in distribution of N due to additional N supply.

A fully habituated (auxin- and cytokinin-independent) self-regenerating (organo-genic) sugar beet cell line (HO) and a fully habituated non-organogenic one (HNO) derived from the former one, were analyzed as to their nuclear size and DNA content. Flow cytometry and image analysis were used and cells of certified diploid leaves of the same sugar beet strain served as controls. The HNO cells had been shown previously to have many characteristics of cancerous cells. The analyses made on leaves and HNO cells indicated the presence of only one population of cycling cells. In HO cells, two cycling populations were detected: the first one had the same DNA content as the leaves while the second one contained two fold more DNA than the first population. HNO cells showed the higher nuclear size and DNA content. HNO cells also showed evidence of aneuploidy. Thus, nuclear size, DNA content and ploidy level increase together with the neoplasic progression to culminate in HNO cells with the loss of organogenic totipotency.

Using various transformation methods, T-DNA constructions for insertional mutagenesis were introduced into Arabidopsis thaliana and the pattern of segregation of hygromycin resistance selectable marker was followed in succeeding generations in individual transgenic lines up to T₄ generation. Despite the low frequency of transformation, T-DNA was often inserted in two or more independent sites. Mendelian segregation ratios 3:1, 15:1, and irregular segregation ratios were observed. We have also shown continuous decrease of the expression of the resident hygromycin resistance transgenic trait in some lines.

The protein profile of cells of control somatic embryos was compared to that of embryos that have become selected and maintained on 200 mM NaCl in order to detect salt inducible proteins. Two proteins (60 and 51.5 kDa) were more abundant in the selected embryos and one protein with molecular mass 18 kDa was unique to the selected embryos. Enhanced content of 27 kDa protein was observed in all somatic embryos indicating its involvement in the embryonal state. Similar pattern of salt inducible proteins in selected somatic embryos and the plantlets regenerated from such embryos was found.

Ultrastructure of leaf mesophyll and two-layer trap wall of Utricularia vulgaris L. was studied after 24-h and 48-h treatment with different concentrations of cadmium. The treatment of plants with 0.25 g(Cd²⁺) m^-3 caused different changes in the chloroplasts of the two organs. The thylakoids swelled in chloroplasts of leaf and the starch content increased in chloroplasts of traps. Higher concentrations of Cd (0.5 and 1.5 g m^-3) caused osmiophilisation of thylakoids in the chloroplasts of both studied organs. The secretory cells in the trap wall was resistant to Cd.

Total chlorophyll (Chl) content, leaf mass per area (LMA), and net photosynthetic rate (P_N) were studied in four cultivars of mango (Mangifera indica L.) from September to May. Maximum Chl contents were found in September and December, the period considered to be crucial for flowering in mango. P_N was maximum during October and maintained almost steady during the fruit growth period. However, LMA varied significantly in all cultivars. Mean Chl content, P_N and LMA were lower in cv. Malaviyabhog than in other cultivars.

Treatment of excised marrow (Cucurbita pepo L., zucchini) cotyledons with methyl ester of jasmonic acid (MeJA) had no effect on their growth in darkness. On the other hand, MeJA induced the synthesis of three polypeptides (69, 60 and 43 kDa) and stimulated the accumulation of other polypeptides (97.4 and 53 kDa). These changes in the polypeptide profile were accompanied by a suppression of total protein and RNA synthesis as well as the activity of nuclear RNA polymerases. In contrast to MeJA, N⁶-benzylaminopurine (BAP) significantly enhanced cotyledon growth and stimulated protein and RNA synthesis. Furthermore, BAP, when applied together with MeJA, was able to counteract some effects of MeJA including the appearance of specific MeJA-induced polypeptide bands.

Root growth of Sinapis alba seedlings was used to determine the interactions (antagonism, synergism, and indifference) among Cu²⁺, Ni²⁺, Mo⁶⁺, Mn²⁺ and V⁵⁺ (each to each). For majority of combinations the antagonistic or indifferent effect was observed. The synergism was confirmed only between Ni and V, Mo and V, and Cu and V. V and Mn had reciprocal antagonistic effect each other, and Mn was like as Mo and Cu the antagonist to Ni. Molybdenum came up reciprocal indifference with regard to Cu and Mn, Mn and Ni did not influence unfavourable effect of Cu on S. alba root growth.

Shoots of Bacopa monniera exhibited 100 % regeneration on Murashige and Skoog medium with 2 % sucrose, 0.2 mg dm^-3 1-naphthaleneacetic acid, 0.5 mg dm^-3 6-benzylaminopurine and 50 mg dm^-3 glutamine. When the medium was supplied with various concentrations (5 - 15 g dm^-3) of sodium chloride, proline content in regenerants was six times higher than in the control. With increasing NaCl concentration photosynthetic rate decreased and fresh mass and root length of regenerants declined. NaCl also induced formation of new proteins.

The effect of indole-3-acetic acid (IAA) and gibberellic acid (GA₃) applications on parthenocarpic fruit set in Rosa canina and Diospyros lotus was investigated. GA₃ induced parthenocarpic fruit set in both plants, but IAA only in D. lotus. Maturation of seedless fruits was earlier than the seeded fruits. GA₃ caused a decrease in the fresh mass and size of both fruits. IAA induced an increase in the fresh mass and size in parthenocarpic fruit of D. lotus.

Growth and structural responses of primary roots of Zea mays L. to aluminium chloride were studied. The treatment of seedlings with 50 µM AlCl₃ resulted in high accumulation of Al, partial inhibition of root growth, occurrence of surface lesions in peripheral tissues, root thickening caused by expansion of inner cortical cells, reduced root cap length, extensive vacuolation, cell distortion, and increased synthesis of callose within 24 h.

The in vitro regeneration of three flax (Linum usitatissimum L.) breeding lines (cv. Jitka, cv. Areco and NLN 245) and selection of transgenic plants were studied. A. tumefaciens derived binary vector GV3101 (pPM90RK)(pPCVRN4) bearing tetramer of 35S promoter enhancer was used in transformation experiments. Following 3 weeks of cultivation on shoot inducing Murashige and Skoog agar medium containing BAP (0.1 µM) and NAA (0.005 µM) from 82.6 % to 98 % of hypocotyl segments formed shoots. While ticarcillin (500 mg dm^-3) used to eliminate Agrobacterium following the transformation decreased the organogenic response by about 10 % only, the addition of 20 mg dm^-3 hygromycin to ticarcillin efficiently suppressed the regeneration of untransformed control plants. To look up for genomic mutations caused by T-DNA insertion from Agrobacterium transformation or originated from somaclonal variation over 500 regenerated plants have been cloned, transferred into soil and evaluated especially for their morphological characteristics. Up to now among plants of cv. Areco-background at least 8 genotypes showed changes either in flower or filament and stigma colour and one clone of plants with pollen sterility was identified. Among fifty four plant clones evaluated in 7 clones the presence of transgene specific sequence hpt was detected and simultaneously Agrobacterium contamination of tissues was firmly excluded.

Micropropagation and Agrobacterium-mediated transformation were developed in Kalmia latifolia cv. Ostbo Red. The transformation of Kalmia latifolia plants was carried out by an Agrobacterium tumefaciens strain containing the nptII and gusA genes in its T-DNA. Shoots were regenerated on kanamycin selection medium and the expression of the gusA reporter gene was verified by fluorogenic β-glucuronidase (GUS) assay in a few vegetative generations after regeneration. The presence of the gusA gene in regenerated kanamycin resistant plants was detected by polymerase chain reaction.

The isolation and characterisation of cotyledonary ribonucleases (RNase; EC 3.1.27.1), are basic steps to understand the physiology and biochemistry of RNA turnover and mobilisation during seed germination and seedling establishment, as well as how environmental stresses affect them. RNase was isolated and purified 928-fold, to apparent electrophoretic homogeneity from 5-d-old seedlings of Vigna unguiculata. It is a protein with an apparent molecular mass of 16 kDa having three major isoforms. Its optimum pH is 5.8, which decreases to 5.2 in presence of KCl. It has an apparent K_m of 0.80 mg RNA cm^-3 and retains 40 % of its activity when heated to 80 °C. It is completely inhibited by Cu²⁺, Hg²⁺ and Zn²⁺ and is almost insensitive to Mg²⁺, Ca^2+- and EDTA. Urea, Fe²⁺, Co²⁺ and 2-mercaptoethanol partially inhibit its activity. Its amino acid composition shows a resem lance to that of other plant RNases.

An endopolygalacturonase (endo-PG), was purified from the culture medium of a local isolate of Sclerotinia sclerotiorum with ammonium sulphate precipitation, cation exchange chromatography and gel filtration. The purified endo-PG had a molecular mass of approximately 18 kDa estimated by gel filtration. The isoelectric point was determined by isoelectric focusing to be approximately 8, suggesting that PG II possesses a net positive charge at physiological pHs. The pH optimum for the enzyme was at pH 4.5. The endo-PG showed essentially the same affinity for pectin and polygalacturonic acid as substrates.

Exposure of Helianthus annuus L. seedlings to Al³⁺, Cd²⁺ or Zn²⁺ resulted in a marked decrease of fresh and dry masses of the shoots and the roots. The increase of Al³⁺, Cd²⁺ or Zn²⁺ uptake was accompanied by a significant decrease of nitrate, phosphorus and K⁺ uptake. There was a significant increase of malic and citric acid contents in the shoots and roots of heavy metal-treated seedlings whereas the change in fumaric acid was insignificant. Al³⁺ and Zn²⁺ alone stimulated excretion of malic and citric acids to the rhizosphere. Addition of high concentrations of malic or citric acid alleviate to some extent the inhibitory effect of Al³⁺ and Zn²⁺ on plant growth.