A greenhouse experiment was conducted to assess the effect of 25, 50, 75, and 100 mM NaCl on growth, ion accumulation, seed yield, and seed oil content in 67-d-old plants of Foeniculum vulgare Mill. Increasing NaCl concentration caused a significant reduction in fresh and dry masses of both shoots and roots as well as seed yield. Na⁺ and Cl^- in both shoots and roots increased, whereas K⁺ and Ca²⁺ decreased consistently with the increase in NaCl concentration. Plants maintained markedly higher Ca²⁺/Na⁺ ratios in the shoots than those in the roots, whereas that of K⁺ /Na⁺ ratios remained almost uniform in both shoots and roots. Proline content in the shoots increased markedly at the highest NaCl concentration. Oil content in the seed decreased progressively with increase in salinity.

Comparative studies on rooting and growth performance of cuttings raised from in vitro and in vivo grown plants of Rosa damascena are described. Cuttings were treated with different auxins and upon transfer to soil their growth performance was recorded. Overall, the auxin treated cuttings of in vitro raised plants responded better than the cuttings of in vivo raised plants. Optimal response for percentage of rooting, root number, root length and bottom breaks was observed at 100 mg dm^-3 IBA. The cuttings derived from in vitro raised plants showed a significantly better response for percent rooting, root number, root length and bottom buds in control treatments.

In vitro regeneration of four Begonia genotypes, B. semperflorens, B. rex, B.×elatior, and hybrid of Begonia with unknown parents 'Tiger' was carried out starting from leaf and petiole segments as explants. Five Murashige and Skoog's derived media were tested, three of them supplemented with α-naphthaleneacetic acid (NAA) and 6-benzyladenine (BA), and the other two with NAA and kinetin (KIN) in different concentrations. Shoot regeneration was preferentially induced on the BA containing media, quantitative differences being observed among explants and genotypes.

The aim of this work was to assess the responses of seedlings of five species of Nicotiana genus to red and far red radiation. N. acuminata exhibits positive photoblastic behaviour and germination was completely inhibited under far red and darkness. In N. glauca germination was reduced under far red and darkness, but the other species showed neutral behaviour. The hypocotyl elongation was inhibited in N. glauca and N. tabacum under white and far red radiation. In N. langsdorffii and N. debneyi hypocotyl was elongated under far red radiation. Only in N. acuminata red radiation promote greater hypocotyl elongation than dark condition. On the phylogenetic tree obtained from restriction analysis N. glauca and N. acuminata are grouped in one branch, while the other species, N. langsdorffii, N. debneyi and N. tabacum, are grouped in the other branch cluster. Moreover, the N. debneyi behaviours under different radiation treatments were similar to those of N. tabacum. These two species are allopolyploid members of the genus Nicotiana, as also was confirmed by this study.

The impact of aluminium stress on activities of enzymes of the oxidative metabolism: superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POD), NADH peroxidase (NADH-POD) and oxalate oxidase (OXO) was studied in barley (Hordeum vulgare L. cv. Alfor) root tips. SOD appeared to be involved in detoxification mechanisms at highly toxic Al doses and after long Al exposure. POD and APX, H₂O₂ consuming enzymes, were activated following similar patterns of expression and exhibiting significant correlation between their elevated activities and root growth inhibition. The signalling role of NADH-POD in oxidative stress seems to be more probable than that of OXO, which might be involved in Al toxicity mechanism.

Using monoclonal FITC conjugated antibodies that specifically recognize phosphorylated form of threonine (α-T^P-FITC) it was shown that in excised, sugar-starved root meristems of Vicia faba subsp. minor the expression of two principal control points (PCPs) is correlated with a marked decrease in nuclear and nucleolar phosphorylation of proteins. When stationary phase meristems are supplied with 2 % sucrose, the G1-arrested cells start out DNA replication (assessed by pulse ³H-thymidine labeling), while the cells blocked in G2 phase initiate mitotic divisions. Using this model, we have found that depending on the period during which the sucrose-mediated PCP1→S and PCP2→M transitions are affected by 6-dimethylaminopurine, an inhibitor of protein kinases, the release from G1 and G2 phase arrest-points of the cell cycle become prolonged, showing different time-course modifications. Furthermore, our results seem to implicate that both PCP1 and PCP2 comprise subpopulations of cells differing with respect to the rates at which they commence DNA replication and mitosis.

It is suggested that cathodal esterase isoenzyme (E₁) might be used as a marker for the VA 1 gene on 7 S maize chromosome and for the "B" linkage group of Tripsacum dactyloides in Zea mays L. ×T. dactyloides L. hybrids. The latter genic zones have a regulatory effect on fertility and on the apomictic mode of reproduction.

Androgenic lines of Brassica juncea cv. PR-45 raised by anther culture, were screen for genetic variation. 393 androgenic plants were transferred to pots to study the R₀ generation. These plants showed substantial variation for different characters. Seed progenies of 27 lines of R₀ plants were sown in the field to study R₁ generation. Androgenic plants within lines were significantly homogeneous for the various agronomic characters studied. Two lines were shorter (18 - 20 %) than the control plants, with a remarkable feature of early maturation. Three lines showed 27 - 31 % higher yield than the parent cultivar.

In vitro shoot culture was applied to an Italian local cultivar Nebbiara of olive (Olea europaea L.) to preserve its endangered germplasm. This cultivar showed a notable difficulty for the in vitro establishment due to heavy pathogen contamination. Mercury chloride and sodium hypochloride in the sterilisation step and antibiotics in culture media allowed to overcome the problem. Proliferation of shoot apical bud on olive culture medium with 36 g dm^-3 mannitol and 4.56 μM zeatin appeared very satisfactory. All the explants tested rooted during a subculture (1 month) preceeded by a 5-d long dark pre-treatment.

Two experiments were conducted independently with plants of cassava (Manihot esculenta Crantz) growing in sand with nutrient solutions with four nitrate concentrations (0.5, 3, 6 or 12 mM). In leaves, nitrate-N was undetectable at the low nitrate applications; total-N, ammonium-N, amino acid-N, reduced-N and insoluble-N all increased linearly, while soluble proteins did it curvilinearly, with increasing nitrate supply. In contrast, soluble-N did not respond to N treatments. Total-N and soluble proteins, but not nitrate-N or ammonium-N, were much higher in leaves than in roots. Plants grown under severe N deficiency accumulated ammonium-N and amino acid-N in their roots. Further, plants were exposed to either 3 or 12 mM nitrate-N, and leaf activities of key N-assimilating enzymes were evaluated. Activities of nitrate reductase, glutamine synthetase, glutamate synthase and glutamate dehydrogenase were considerably lower in low nitrate supply than in high one. Despite the low nitrate reductase activity, cassava leaves showed an ability to maintain a large proportion of N in soluble proteins.

Elevated UV-B radiation (12.2 kJ m^-2 d^-1) as against the ambient level of 10 kJ m^-2 d^-1 affected flowering, productivity and biomass partitioning of green gram [Vigna radiata (L.) Wilczek cv. KM-2]. UV-B stress delayed flowering initiation and achievement of 50 % flowering, reduced flower retention by 25 %, potential yield by 18 % and all yield attributes such as pod number (25 %), pod mass (41 %), seed number (32 %) and seed mass (45 %). Harvest index and shelling percentage were also reduced by 31 and 7 %, respectively. Application of triadimefon (20 mg dm^-3) to unstressed plants accelerated flowering and enhanced flower retention (21 %), potential yield (15 %) and yield attributes (7 to 44 %). The partitioning of biomass between plant parts also showed improvement over the control plants. In UV-B-stressed plants, triadimefon treatment compensated the inhibitions to varying extents.

A Na⁺/H⁺ antiporter catalyzes the transport of Na⁺ and H⁺ across the tonoplast membrane. We isolated a vacuolar Na⁺/H⁺ antiporter cDNA (SsNHX1) clone from a euhalophyte, Suaeda salsa. The nuclear sequence contains 2262 bp with an open reading frame of 1665 bp. The deduced amino acid sequence is similar to that of AtNHX1 and OsNHX1 in rice, with the highest similarities within the predicted transmembrane segments and an amiloride-binding domain. Northern blot analysis shows that the expression of the S. salsa gene was increased by salt stress. The results suggest that the SsNHX1 product is likely a Na⁺/H⁺ antiporter and may play important roles in the salt tolerance of S. salsa.

The chloroplast within the plant cell has a dynamic environment where proteases play an important role in processing of precursor proteins, degradation of incomplete proteins lacking cofactors, stress-induced degradation and removal of damaged proteins. A number of proteases in the chloroplast are well characterized and found to be localized within different compartments such as stroma, thylakoids and lumen. In recent years, an increasing number of proteases in chloroplasts have been discovered and identified as bacterial protease homologues. These include the stromal Clp, thylakoidal FtsH and lumenal DegP. The current focus is to understand their role in chloroplast regulation both at the enzyme-substrate and genetic levels.

Effect of pre-treatments of 1 and 5 μM epibrassinolide or homobrassinolide prior to water stress induction on changes in root nodulation and contents of endogenous abscisic acid (ABA) and cytokinin trans-zeatin riboside (ZR), and nitrogenase activity was investigated in the nodulated roots of Phaseolus vulgaris L. cv. Arka Suvidha. Brassinosteroids in the unstressed plants increased root nodulation, ZR content and nitrogenase activity, and also ameliorated their stress-induced decline in the nodulated roots. The ABA contents in the nodules of control or stressed plants were not altered by brassinosteroids treatment. There was an increase in pod yield by brassinosteroids treatment (5 μM) in the irrigated control as well as stressed plants without influencing pod number or pod length. Among the brassinosteroids, epibrassinolide was relatively more effective.

The lignin contents and anatomical structure of roots of wild cherry (Prunus avium L.) and pedunculate oak (Quercus robur L.) plantlets were compared to explain differences in response during transfer from in vitro to ex vitro conditions. Lignification of cell walls increased significantly in both oak and cherry roots during the period of acclimation and finally lignin content of root tissues of in vitro propagated plantlets reached the levels not significantly different from seedlings grown in soil. Later on when secondary tissues appeared, lignified secondary xylem constituted most of the tissues of both species. The most conspicuous interspecific difference in root structure was the presence of phi-thickenings in cortical layers just outer to endodermis in cherry roots cultivated ex vitro. Formation of phi-thickenings was avoided in vitro and their presence thus seems to be under environmental control. Suberised well established exodermis was present in roots of oak but not detected in those of cherry. Very early development of exodermis in oak roots, preceding suberisation of endodermis, was recorded in vitro but not in well aerated soil. While multilayered and well-developed cork occurred in oak, only thin walled and less suberised secondary dermal tissues were found in cherry.

Seeds of Cassia angustifolia Vahl. were subjected to 0, 20, 50, 100 mM NaCl for 7 d in order to study the effect of salt stress on growth parameters, endogenous Na⁺ and Cl^- concentrations, antioxidant system, lipid peroxidation, hydrogen peroxide, and proline contents. Salinity affected all of the considered parameters and caused a great reduction in plant biomass. The root and shoot length, fresh and dry mass and germination percentage were inhibited by NaCl treatments. These changes were associated with an increase in the Na⁺ and Cl^- contents in the seedlings and increased activities of superoxide dismutase, catalase, peroxidase, and polyphenol oxidase. The increased enzyme activity coincided with decreased ascorbate content and enhanced H₂O₂ and proline content.

A new protocol for micropropagation of endangered Daphne cneorum through multiple shoot formation has been developed. Two different types of explants (dormant apical buds and in vitro seed-derived young seedlings) from plants in two different localities were used for the initiation of multiple shoots on agar woody plant medium (WPM) with 0.2 mg dm^-3 benzylaminopurine (BAP), 0.1 mg dm^-3β-indolebutyric acid (IBA), 200 mg dm^-3 glutamine, and 200 mg dm^-3 casein hydrolysate. From 10 seeds only one germinated and the multi-apex culture bearing 12 shoots sprouted out from in vitro seed-derived young seedling. After 6-month cultivation 35 multi-apex cultures were achieved from in vitro seed-derived young seedling. On 1/3 strength WPM medium supplemented with 2.83 mg dm^-3 IBA 50 % of cultures (clusters of 3 - 5 shoots) rooted but no rooting occurred in the presence of α-naphthaleneacetic acid (NAA). The rooted plantlets were acclimatized for 4 weeks in the greenhouse and then transferred into natural conditions. The plants successfully survived the winter and flowered.

We employed continuous irradiation (CL) for induction of premature senescence caused by enhanced production of reactive oxygen species. As a model plant we used bean (Phaseolus vulgaris L. cv. Jantar) cotyledons because they have well defined and a quite short life span. Senescence of bean cotyledons induced by CL progressed more rapidly than natural senescence: the life span of CL cotyledons was 13 d compared to 16 d in controls (C). Chl content was significantly lower in 10- and 13-d-old CL plants than in C plants and the change with age was not statistically significant. Activities of all antioxidative enzymes declined either with senescence onset or during whole life span. Activity of antioxidative enzymes, except ascorbate peroxidase, was lower in CL plants compared to C plants. On the contrary, contents of non-enzymatic antioxidants β-carotene and ascorbate were higher in CL plants than in C plants. No significant difference, except in the youngest cotyledons, was observed in glutathione content.

Shoot tip explants of cucumber (Cucumis sativus L. cv. Poinsett 76) were cultured in vitro on Murashige-Skoog medium with L-glutamine, ammonium nitrate, adenine sulphate, asparagine, ammonium succinate, potassium nitrate and sodium nitrate as the nitrogen sources along with optimal concentration of 0.044 mM benzyladenine to study their effects on in vitro morphogenesis. The explants grown with 0.068 mM L-glutamine displayed the highest culture response (74.6 %) and greatest shoot number per explant (13.6) at the end of two subcultures. The explants cultured with other nitrogen sources resulted in low culture frequency and low number of shoots per explant accompanied by basal callusing and necrosis.

We have designed and constructed four oligonucleotides corresponding to the most conserved regions of ornithine decarboxylases (ODC; EC 4.1.1.17) of plant origin. These oligonucleotides were used for the amplification of homologous fragments from several plants (Zea mays, Capsicum annuum, Sorghum bicolor, Phaseolus vulgaris, Carica papaya and Daucus carota). The amplified fragments were cloned and sequenced, revealing high homology to other ODCs. Peptide sequences coded by these fragments were compared by Clustal analyses. These analyses identified the location of the conserved sequences corresponding to the binding sites of substrate and cofactor. Data demonstrated that the plant ODCs fragments lacked intron sequences and were extremely homologous (over 80 %), constituting a compact group separated from other eukaryotic ODCs.

Exposure of barley plants (Hordeum vulgare L.) to soil flooding for 72 - 120 h led to decrease in the content of the both subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase. The effect was more pronounced on the small subunit. Further, the changes in protein pattern were observed, mainly proteins with molecular masses 30 - 85 kD were down-regulated.

Programmed cell death (PCD) was triggered in wheat leaves by a heat treatment (42 °C). This treatment caused DNA fragmentation as shown in DNA laddering analysis and in terminal deoxynucleotidyl transferase-mediated deoxyuridine-5'-triphosphate (dUTP) nick end labeling (TUNEL) analysis. Methanol and acetone treatment of leaves significantly blocked PCD. Western analysis indicated that a 65 kDa poly(ADP-ribose) polymerase-like protein was degraded during the treatment. However, high temperature (80 °C) treatment caused necrosis but not PCD.

Effects of 28-homobrassinolide (HBR) and kinetin (KIN) on photosynthesis, nitrogen metabolism, and the seed yield were studied. The leaves of 25-d-old plants of Vigna radiata (L.) Wilczek were sprayed with 0.01, 1.0 or 100 μM aqueous solution of KIN, or 0.0001, 0.01 or 1.0 μM that of HBR. KIN and especially HBR increased the activities of nitrate reductase and carbonic anhydrase, chlorophyll and total protein contents and net photosynthetic rate in the leaves, and pod number and seed yield, at harvest.

Trigonelline (TRG), which act as a cell cycle regulator and a compatible solute in response to salinity and water-stress, is the N-methyl conjugate of nicotinic acid the formation of which is catalyzed by S-adenosyl-L-methionine nicotinic acid-N-methyltransferase. The enzyme was purified 2650-fold from soybean (Glycine max L.) leaves with a recovery of 4 %. The purification procedure included ammonium sulfate (45 - 60 %) precipitation, linear gradient DEAE-Sepharose chromatography, adenosine-agarose affinity chromatography, hydroxyapatite chromatography and gel filtration (Sephacryl-S-200). The purified enzyme preparation showed a major band with a molecular mass of 41.5 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis that is related to the enzyme activity. The native enzyme had a molecular mass of about 85 kDa as estimated by gel filtration. The K_m values for S-adenosyl-L-methionine and nicotinic acid were 31 and 12.5 μM, respectively. The purified enzyme showed optimum activity at pH 6.5 and temperature of 40 - 45 °C. High concentration of dithiothreitol (10 mM) and glycerol (20 %) stabilize the enzyme during purification and storage. Hg²⁺ strongly inhibits enzyme activity.

Effects of NaCl on growth in vitro and contents of sugars, free proline and proteins in the seedlings and leaf explants of Nicotiana tabacum cv. Virginia were investigated. The fresh and dry mass of the seedlings decreased under salinity. These growth parameters in leaf explants decreased at 50 mM NaCl and increased up to 150 mM NaCl and then decreased at higher level of salinity. Free proline content in both seedlings and leaf explants increased and polysaccharide content decreased continuously with increasing of NaCl concentration. Reducing sugars, oligosaccharides, soluble sugars and total sugars contents in both seedlings and leaf explants decreased up to 150 mM NaCl and then increased at higher concentrations of NaCl.

This paper describes rapid propagation of Sesbania drummondii using nodal explants isolated from seedlings and young plants. The nodal segments proliferated into multiple shoots on Murashige and Skoog's (MS) medium supplemented with 22.2 μM benzyladenine. MS medium containing 2.2 and 4.5 μM thidiazuron induced 5 - 6 shoots per stem node from 3-month-old plants. Nodal explants when cultured on MS medium containing combinations of benzyladenine (8.8 and 11.1 μM) and indole-3-butyric acid (0.24 - 2.46 μM) or indole-3-acetic acid (0.28 - 2.85 μM) gave lesser number of shoots. Callus induced on cotyledonary explants when subcultured on 2.2 μM thidiazuron containing medium resulted in its mass proliferation having numerous embryoid-like structures. Indole-3-butyric acid (0.24 - 2.46 μM) was found suitable for root induction. In vitro regenerated plants were acclimatized in greenhouse conditions.

This study was conducted to examine the response of date palm (Phoenix dactylifera L., cvs. Barhee and Hillali) calli to water stress. Callus derived from shoot tip explants was inoculated in liquid Murashige and Skoog medium containing 10 mg dm^-3α-naphthaleneacetic acid, 1.5 mg dm^-3 2-isopentenyladenine, and 0 to 30 % (m/v) polyethylene glycol (PEG 8000) to examine the effect of water stress. After 2 weeks, callus growth, water content, and proline accumulation were assessed. Increasing water stress caused a progressive reduction in growth as expressed in callus fresh mass, relative growth rate, and index of tolerance. Both genotypes tested followed this general trend, however, cv. Barhee was more tolerant to drought stress than cv. Hillali. Increasing PEG concentration was also associated with a progressive reduction in water content and increased content of endogenous free proline.

Embryogenic suspension cultures of soybean (Glycine max L. cv. Iroquois) were subjected to mutagenesis using varying concentrations (1, 3, 10, and 30 mM) of ethyl methanesulfonate (EMS). Depending on the concentration of EMS used, the mean survival rate of embryogenic cultures decreased from 74 % (1 mM EMS) to 43 % after 30 mM EMS treatment. Random amplified polymorphic DNA (RAPD) analysis was used to determine whether induction of genetic variability in embryogenic cultures in response to the different EMS treatments may result in identification of polymorphic markers. Two of 35 'core' primers tested revealed polymorphisms. One of the primers, OPO-01/1150, revealed polymorphism in tissue treated with 10 mM EMS, while the other primer, OPO-05/1200, revealed polymorphism in tissue treated with either 1 or 30 mM EMS. These results suggest that RAPD markers are useful in detecting mutations in embryogenic cultures of soybean.