Transgenic rice plants in which the content of dienoic fatty acids was increased as a result of co-suppression of fatty acid desaturase were more tolerant to high temperatures than untransformed wild-type plants, as judged by growth rate and chlorophyll content. When untransformed wild-type and transgenic rice seedlings were incubated at 35 °C, seedlings of the transgenic rice lines showed approximately 1.6 and 2.1 times the growth of untransformed wild-type seedlings, as assayed by shoot and root mass, respectively. The chlorophyll content of the transgenic leaves after 9 d at 35 °C was also higher than that of wild-type rice. The maximum photochemical efficiency of photosystem 2 was also higher in transgenic plants than in wild-type plants upon high temperature stress.

An in vitro method for propagation of Holarrhena antidysenterica Wall. has been developed using nodal explants from mature trees growing in the field. Irrespective of concentrations and combinations of growth regulators used, the axillary and terminal buds sprouted and elongated when inoculated on Murashige and Skoog (MS) medium. The highest numbers of shoots were formed when sprouted shoots were subcultured from MS basal medium onto MS medium containing 2 mg dm^-3 N⁶-benzyladenine (BA) and 0.5 mg dm^-3 α-naphthalene acetic acid (NAA). The shoot number further increased upon subculture on MS medium containing 0.5 mg dm^-3 BA. By repeated sub-culturing of shoots derived from nodal axillary buds, a high frequency multiplication rate was established. The elongated shoots were excised and rooted in auxin free MS basal medium. Ex vitro rooting of in vitro formed shoots was achieved upon dipping the microshoots for 2 min in 2 mg dm^-3 of indole-3-butyric acid solution. Successful field establishment and high (80-90 %) survival of plants was observed.

A study was conducted to evaluate in vitro techniques for germplasm preservation of wild species of Arachis. Nodal segments excised from in vitro-grown plants of A. retusa, A. macedoi and A. burchellii were used to examine the effects of explant position and age of the donor plant. Explants were excised from plants maintained in culture for 30, 60, 90 or 180 d, numbered I - V from top to bottom and cultured on MS medium supplemented with 2.7 µM NAA or different BAP concentrations (0, 4.4, 13.2 and 22 µM). The age of the donor plant has not influenced the responses of the four genotypes studied. In contrast, shoot regeneration ability was significantly affected by the original explant position, decreasing from top to bottom. In media supplemented with different BAP concentrations, multishoot formation was induced from apical segments at low frequencies (10 - 20%) and segments of all positions originated calluses at the explant basis after 30 d of culture. The culture of nodal segments in the presence of 2.7 µM NAA as the sole growth regulator is recommended for the multiplication of in vitro collections of wild groundnut species in order to avoid callusing and adventitious shoot formation.

Hairy roots of Rhamnus fallax Boiss. were induced using Agrobacterium rhizogenes strain A4M70GUS. The culture established on Woody plant media (WPM) showed a typical hairy root phenotype: rapid growth, reduced apical dominance and root plagiotropism. Seven clones of R. fallax were selected on the basis of their differences in colour and the root branching. The growth of hairy root culture, measured through gain in fresh mass, was done under 16-h photoperiod or in the dark. An increase in anthraquinone (AQ) content was obtained in clones with yellow and less branched roots, like clone 1 [16.43 mg g^-1(d.m.)] and clone 7 [14.21 mg g^-1(d.m.)], compared with other analysed transformed and non-transformed tissue. This study presents the first report of successful transformation of any species from family Rhamnaceae by A. rhizogenes and analysis of AQ production in transformed tissue.

The interplay between nitric oxide (NO) and reactive oxygen species can lead to an induction of cell death in plants. The aim of our work was to find out if cyanide released from sodium nitroprusside (SNP; a donor of NO) could be involved in the cell death induction, which is triggered by SNP and H₂O₂. Cell suspension of Nicotiana tabacum L. (line BY-2) was treated with 0.5 mM SNP, 0.5 mM potassium ferricyanide (PFC; analogue of sodium nitroprusside which can not release NO) and/or by 0.5 mM glucose with 0.5 U cm^-3 glucose oxidase (GGO; a donor system of H₂O₂). The cell death was induced only by combination of SNP and GGO. Thus cyanide released was not involved in the induction of cell death. However, SNP showed toxic effect because of decrease in activities of intracellular oxidoreductases and esterases. The cell death caused by SNP and GGO occurred within 12 h. During cell death either length or width of the cell increased. Central vacuole was formed in 20 to 40 % of cells. Most of the dead cells showed a condensed cytoplasm. Two hallmarks of programmed cell death (PCD), chromatin condensation and blebbing of nuclear periphery, were observed. However, oligonucleosomal fragmentation of DNA, another hallmark of PCD, was not detected.

The phytoremediation is an environment friendly, green technology that is cost effective and energetically inexpensive. Metal hyperaccumulator plants are used to remove metal from terrestrial as well as aquatic ecosystems. The technique makes use of the intrinsic capacity of plants to accumulate metal and transport them to shoots, ability to form phytochelatins in roots and sequester the metal ions. Harbouring the genes that are considered as signatures for the tolerance and hyperaccumulation from identified hyperaccumulator plant species into the transgenic plants provide a platform to develop the technology with the help of genetic engineering. This would result in transgenics that may have large biomass and fast growth a quality essential for removal of metal from soil quickly and in large quantities. Despite so much of a potential, the progress in the field of developing transgenic phytoremediator plant species is rather slow. This can be attributed to the lack of our understanding of complex interactions in the soil and indigenous mechanisms in the plants that allow metal translocation, accumulation and removal from a site. The review focuses on the work carried out in the field of metal phytoremediation from contaminated soil. The paper concludes with an assessment of the current status of technology development and its future prospects with emphasis on a combinatorial approach.

Quantitative trait loci (QTLs) for Cu-tolerance were determined in wheat grown in control and Cu-treated soil in greenhouse. In addition, loci having an influence on the shoot Cu-, Fe-, Mn-and Zn-contents under non-stressed and Cu-stressed environments were mapped. One major QTL for Cu-tolerance was found on chromosome 5DL, while slighter effects were determined on the chromosomes 1AL, 2DS, 4AL, 5BL and 7DS. QTLs affecting the shoot Mn-and Zn-contents were found on the chromosomes 3BL and 3AL, respectively. The centromeric region on the chromosome 3B plays a role in the regulation of the shoot Fe-contents in the stressed plants. Under Cu-stress QTL affecting shoot Cu-content was found on chromosome 1BL, while on the chromosome 5AL a QTL influencing the Cu-accumulation ability of wheat from Cu-polluted soil was determined.

Water potential (ψ_w) and water saturation deficit (WSD), and several reflectance (R) indexes were assessed in an aerophytic lichen Umbilicaria hirsuta (Sw. ex Westr.) Hoffm. The water index (WI, R₉₀₀/_R970) and normalized difference vegetation index, NDVI [(R₉₀₀-R₆₈₀)/(R₉₀₀+R₆₈₀)] were strongly correlated both with the ψ_w and the WSD of lichen thalli. No significant changes during desiccation were found in structural independent pigment index, SIPI [(R₈₀₀-R₄₄₅)/(R₈₀₀-R₆₈₀)]. Sensitivity of the spectral detection of water status was rather small at high hydration level (WSD < 25 %, or ψ_w > -1 MPa), but this is not much limiting its value and potential use, because physiological processes in lichens are usually inhibited at much lower values of ψ_w than in leaves of vascular plants.

Foliar sprays of water or 1, 10 and 100 µM aqueous solutions of gibberellic acid (GA₃) or kinetin (KIN) were applied to 40-d-old plants of Nigella sativa (L.) to study their effects on net photosynthetic rate, nitrogen metabolism, and the seed yield. 10 µM solutions of both the hormones, especially GA₃, appreciably increased the activities of nitrate reductase and carbonic anhydrase, chlorophyll and total protein contents and net photosynthetic rate in the leaves, along with capsule number and seed yield plant^-1, at harvest.

A protocol for induction of direct somatic embryogenesis, secondary embryogenesis and plant regeneration of Dendrobium cv. Chiengmai Pink was developed. Thidiazuron (TDZ) at 0.3, 1 and 3 mg dm^-3 induced 5-25 % of leaf tip segments of in vitro grown plants to directly form embryos after 60 d of culture, and 1 mg dm^-3 TDZ was the best treatment. Somatic embryos mostly formed from leaf surfaces near cut ends, and occasionally found on leaf tips. Higher frequency of embryogenesis was obtained in light than in darkness. During subculture, secondary embryos developed from outer cell layers of primary embryos. All combinations of NAA (0, 0.1, 1 mg dm^-3) and TDZ (0, 0.3, 1, 3 mg dm^-3) increased the multiplication rate of embryos. It takes about 8 months from embryo induction, plantlet formation to eventually acclimatization in greenhouse.

A modified low copy number plant binary vector pUN has been constructed and successfully used to clone unstable DNA sequences. The vector pUN comprises of low copy number, broad host range RK2 replicon from pBin19 and of multiple cloning site (MCS) and T-DNA region, both from a pBINPLUS-derived pLV06 vector. The absence of the ColE1 replicon in the backbone of the binary vector significantly contributed to stability of hardly clonable DNA sequences and enabled their transfer into the tobacco plants through Agrobacterium-mediated transformation.

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.

We report here the successful micropropagation of adult Juniperus phoenicea L. with respective ploidy stability studies. Microcuttings with axillary buds were grown on five media supplemented with different growth regulator combinations. Best elongation rates were achieved on Driver and Kuniyuki (DKW) medium supplemented with kinetin alone or with naphthaleneacetic acid (NAA), while Rugini olive (OM) medium stimulated the development of new branches. Shoots growing on Murashige and Skoog (MS) medium browned and showed necrotic zones. Shoots of second to fourth subcultures usually had higher elongation rates than those of the first culture. For rooting assays, half strength DKW and OM media, different concentrations of growth regulators, auxin continuous exposure vs. dipping and the type of solid matrix were assessed. During rooting assays, two morphotypes were observed with one type having well developed internodes and the other showing hyperhydratation and no internode development. High rooting rates (40 %) were only obtained in the first morphotype shoots exposed for 5 min to 2.4 µM IBA and then transferred to OM medium without growth regulators. Plants were acclimatized in pots containing a mixture of peat and Perlite (3:2) in greenhouse with progressive reduction of relative humidity. A flow cytometric screening for major ploidy changes revealed no differences among the morphotypes and between them and the mother plant. Also the nuclear DNA content of this species was estimated for the first time using flow cytometry (2C = 24.71 pg).

The effect of different cadmium concentrations (6-120 µM) on Hill reaction activity (HRA) of isolated chloroplasts, contents of chlorophylls (Chls) and carotenoids (Cars), and Cd uptake and accumulation in plant organs of Indian mustard (Brassica juncea L. cv. Vitasso) and mung bean [Vigna radiata (L.) Wilczek] were determined. The Cd stress inhibited photochemical activity of isolated chloroplasts of both species and in both tested developmental stages. On the basis of EC₅₀ values, the mung bean showed a higher sensitivity to Cd treatment than Indian mustard. The higher sensitivity of both species was determined in the earlier than in the older developmental stage. The leaves of Cd-treated plants possessed lower contents of Chls and Cars in both species and the negative effect increased with Cd concentration. A difference between species was also found in Cd uptake and accumulation. In both species, Cd was accumulated more in roots than in shoots, with higher accumulation in Indian mustard than in mung bean.

In fern (Anemia phyllitidis) gametophytes cellulose in the walls of the antheridial zone cells which was organized in clusters and spots was transformed via dispersed form to fibrillar arrangement (layered in oblique and perpendicular array in relation to the transverse direction of cell expansion) during antheridiogenesis induced by gibberellic acid (GA₃) and/or enhanced by 1-aminocyclopropane-1-carboxylic acid (ACC). In the ACC-treated gametophytes, where antheridia were not induced, the cellulose was arranged in the same manner. Aminooxyacetic acid (AOA), which inhibits antheridiogenesis and development of fern gametophytes, produced in the cell walls both random and longitudinal type of organization of cellulose microfibrils, however, in the GA₃/AOA-treated plants the oblique type was also observed. The total numbers of cells with perpendicular and/or oblique type of cellulose microfibrils in the GA₃-, GA₃/ACC-and GA₃/AOA-treated gametophytes corresponded to the average number of antheridia formed. Moreover, it was found that the extracts from the gametophytes treated with GA₃ or with the mixture of GA₃ and ACC contained significantly less soluble sugars but more α-amylase-and endoglucanase-released sugars than the extracts from the gametophytes of the other series. Thin layer chromatography of the samples from the cell wall extracts hydrolyzed by endoglucanase contained xylose and cellobiose which suggested that these sugars built the xyloglucans, hemicellulose polymers responsible for tethering of walls of fern gametophyte cells like in higher plants.

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.

Four rice indica genotypes of local importance were transformed with RC7, rice chitinase cDNA clone through Agrobacterium-mediated gene transfer method using mature seed derived calli as explants. The putative hygromycin resistant calli showed varied level of regeneration efficiency ranging from 2.0 to 7.6 %. The stable integration and expression of RC7 was confirmed through polymerase chain reaction (PCR) and Western analysis. Transformation efficiency ranged from 0.9 to 5.2 %. The expression of RC7 (35 kDa chitinase) in different tissues of transgenic plant (root, sheath and leaf) was proved through Western analysis and in terms of increased chitinase activity. The inheritance of transgene was studied through PCR and Western analysis in transgenic plants of Pusa Basmati 1. Bioassays with transgenic plants of local cultivars exhibited enhanced resistance up to 33.3 % to rice sheath blight pathogen Rhizoctonia solani under glasshouse conditions. Enhanced expression or 3-to 4-fold increased activity of chitinase in transgenic plants was correlated with sheath blight resistance.

The paper is focused on two groups of proteins inevitably important for cellulose biosynthesis in vascular plants. These are cellulose synthases and chitinase-like proteins. Cellulose synthases have been the subject of much research, and current conceptions and recent findings are reviewed in this paper. Severe effects of mutations and expression analysis have recently shown that chitinase-like proteins are crucial components of cellulose biosynthesis. However, understanding of their precise function is missed. Further research is to be prompted by an effective idea on it. I propose that chitinase-like proteins could play a role in the assembly of nascent glucan chains into microfibrills. Therefore, cellulose synthases and chitinase-like proteins are possibly sequential elements of the cellulose biosynthesis.

The effect of silicon on the growth, boron concentrations, malondialdehyde (MDA) content, lipoxygenase (LOX) activity, proline (PRO) and H₂O₂ accumulation, and the activities of major antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX)] and non-enzymatic antioxidants (AA) of wheat grown in soil originally with toxic B concentrations were investigated. Applied of 5.0 and 10.0 mM Si to the B toxic soil significantly increased Si concentration of the wheat and counteracted the deleterious effects of B on shoot growth. The contents of PRO, H₂O₂, MDA, and LOX activity of wheat grown in B toxic soil were significantly reduced by Si treatments. Compared with control plants, the activities of SOD, CAT, APX and content of AA were decreased by applied Si. Based on the present work, it can be concluded that Si alleviates B toxicity of wheat by preventing oxidative membrane damage and also translocation of B from root to shoot and/or soil to plant.

Two-year-old potted plants of six Camellia sinensis cultivars (TV-18, TV-26, UPASI-3, UPASI-26, T-78 and HV-39) were subjected to water stress for 4, 8 and 12 d. Relative water content (RWC) of leaves of all cultivars declined with water stress, but in the two drought tolerant cultivars (UPASI-3 and UPASI-26), higher RWC were maintained in comparison to the others. Phenol content and activities of phenylalanineammonialyase, polyphenoloxidase and peroxidase initially increased, but decreased during extended drought. Chlorophyll contents decreased, whereas proline contents increased during water stress. SDS-PAGE analysis of proteins revealed increased accumulation of proteins of intermediate molecular masses (42 - 44 kDa) and low molecular masses (14 - 26 kDa). After 12 d of water stress, most of these proteins disappeared in T-78 and HV-39, but in the other cultivars they were still detectable.

The effect of 24-epibrassinolide (BR₂₇) on cold resistance of rape seedlings was studied by ion leakage and photosynthetic pigment degradation measurements. Aqueous solutions of BR₂₇ were injected into cotyledons or primary leaves of rape plants and these plants were incubated at 2 °C or 20 °C. Cold treatment (2 °C) without BR₂₇ injection elevated the membrane permeability in both primary leaves and cotyledons significantly. Surprisingly, injection of leaves with water or 0.467 % aqueous ethanol solution led to a massive increase in membrane permeability after cold stress at 2 °C. The synergistic effect of leaf infiltration and cold on permeability was abolished by 0.05 and 1.00 µM of BR₂₇ in primary leaves and by 1.00 µM of BR₂₇ in cotyledons. On the other hand, BR₂₇ solutions strongly elevated the membrane permeability at 20 °C, while water and ethanol solutions brought about only negligible increases. Water or ethanol infiltrations strongly reduced the leaf contents of chlorophyll (Chl) a, Chl b and carotenoids at 2 °C but less markedly at 20 °C. However, in seedlings exposed to 2 °C pigments content was significantly higher in BR₂₇-treated leaves as compared to water/ethanol control. There were no differences between pigment contents of leaves injected with BR₂₇ solutions or only water/ethanol at 20 °C. The above data strongly support the stress protecting effect of BR₂₇.

Epicotyl segments of kumquat (Fortunella crassifolia Swingle cv. Jindan) were transformed with Agrobacterium tumefaciens GV3101 harboring neomycin phosphotransferase gene (npt II) containing plant expression vectors. Firstly, the explants were cultured in darkness at 25 °C on kanamycin free shoot regeneration medium (SRM) for 3 d, and then on SRM supplemented with 25 mg dm^-3 kanamycin and 300 mg dm^-3 cefotaxime for 20 d. Finally, they were subcultured to fresh SRM containing 50 mg dm^-3 kanamycin monthly and grown under 16-h photoperiod. Sixty five kanamycin resistant shoots were regenerated from 500 epicotyl explants after four-month selection. Shoot tips of 20 strong shoots were grafted to 50-day-old kumquat seedlings and survival rate was 55 %. Among the 11 whole plants, 3 were transgenic as confirmed by Southern blotting. This is the first report on transgenic kumquat plants, and a transformation efficiency of 3.6 % was achieved.

Randomly amplified polymorphic DNA (RAPD) markers were used to assess genetic stability of 80 micropropagated Hagenia abyssinica plants, 40 of axillary origin and 40 of adventitious origin. The shoots were isolated from the same mother tree and micropropagated for over two years. Among the 83 RAPD primers screened, 16 gave reproducible band patterns. These 16 primers produced 115 bands for each plant. One plant from axillary origin showed two unique bands with primer OPC-11. All other plants showed identical band patterns. Generally, there was no significant difference in the shoot multiplication rate between shoots of axillary and adventitious origin. Indole-3-acetic acid (IAA) resulted in better ex vitro rooting compared to indole-3-butyric acid (IBA) and α-naphthaleneacetic acid (NAA). Non-micropropagated plants that were grown in the greenhouse for about one year were better in ex vitro rooting compared to those of juvenile material and mature tree derived micropropagated plants of the same treatment. Adventitious rooting related oxygenase gene (ARRO-1) isolated from apple (Malus domestica) was not expressed in H. abyssinica using a complementary DNA representational difference analysis fragment (cDNA RDA14) as a probe.

Potted 2-year-old lemon trees [Citrus limon (L.) Burm. fil, cv. Verna] grafted on sour orange (C. aurantium L.) rootstock were subjected to flooding for 3 d. Control plants were irrigated daily to field capacity. Continuously (sap flow, trunk diameter fluctuations) and discretely (predawn and midday leaf water potential, leaf conductance) measured plant-based water status indicators were compared. The sensitivity of the maximum daily trunk shrinkage signal intensity to flooding and its behaviour during the recovery period demonstrated that this indicator is more feasible than the others for use in automatic irrigation. The responses to flooding of continuously and discretely measured plant-based water status indicators were very similar to those observed in response to drought stress indicating that it necessary to use soil water measurement automatic sensors to detect the cause of the stress. The results underlined the robustness of the compensation heat-pulse technique for estimating instantaneous and daily transpiration rates on flooding stress and recovery.

Young plants of a rhizomatous grass Calamagrostis epigejos (L.) Roth were grown from seed in nutrient solutions containing nitrogen in concentrations 0.1, 1.0, and 10 mM. After six weeks of cultivation the plants were defoliated and changes in growth parameters and in content of storage compounds were measured in the course of regrowth under highly reduced nitrogen availability. Plants grown at higher nitrogen supply before defoliation had higher amount of all types of nitrogen storage compounds (nitrates, free amino acids, soluble proteins), which was beneficial for their regrowth rate, in spite of lower content of storage saccharides. Amino acids and soluble proteins from roots and stubble bases were the most important sources of storage compounds for regrowth of the shoot. Faster growth of plants with higher N content was mediated by greater leaf area expansion and greater number of leaves. In plants with lower contents of N compounds number of green leaves decreased after defoliation significantly and senescing leaves presumably served as N source for other growing organs. Results suggest that internal N reserves can support regrowth of plants after defoliation even under fluctuating external N availability. Faster regrowth of C. epigejos with more reserves was mediated mainly by changes in plant morphogenesis.

7-d-old etiolated and green barley seedlings (Hordeum vulgare L. cv. Alfa) were irradiated with UV-B for 30 min and then kept for 24 h in light or darkness. Chlorophyll (Chl) synthesis was inhibited by about 30 % as a result of UV-B irradiation, but there were no significant changes in photochemical activity measured by variable to maximum fluorescence ratio (F_v/F_m), quantum yield (Φ_PS2) and oxygen evolution rate. Electron transport of etiolated seedlings was similar to that of green ones, nevertheless, the Chl content was more then 2-fold lower. Ribulose-1,5-bisphosphate carboxylase/oxygenase large and small subunits were diminished as a result of UV-B irradiation in etiolated and green plants, especially in those kept in the darkness. Catalase activity decreased and total superoxide dismutase activity increased in green and etiolated plants following UV-B treatment. When benzidine was used as a substrate, an isoform located between guaiacol peroxidases 2 and 3 (guaiacol peroxidase X) appeared, which was specific for UV-B treatment. As a result of irradiation, the contents of UV-B absorbing and UV-B induced compounds increased in green seedlings but not in etiolated seedlings.

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.

Systemic acquired resistance (SAR) can be induced in plants by incompatible pathogens, pathogen derived extracts, or certain chemicals as benzothiadiazole (BTH). The aim of this work was to compare changes in peroxidase and chitinase activities, enzymes considered as PR-proteins, caused by BTH and the pathogen Plasmopara halstedii. Hypocotyls from susceptible and resistant BTH-treated sunflower seedlings showed increased peroxidase and chitinase activities. Inoculation with P. halstedii increased chitinase and peroxidase activities in inoculated hypocotyls from susceptible but not from resistant sunflower seedlings.

A simple and reliable protocol for regeneration of okra through somatic embryogenesis from suspension cultures has been developed. Embryogenic callus was obtained from hypocotyl explants cultured on media with Murashige and Skoog (MS) salts, Gamborg (B5) vitamins, 2.0 mg dm^-3 2,4-dichlorophenoxyacetic acid (2,4-D), 1.0 mg dm^-3 naphthaleneacetic acid (NAA), 25 mg dm^-3 polyvinylpyrrolidone and 30 g dm^-3 sucrose. More number and high frequency of healthy embryoids appeared individually in suspension culture containing MS salts, B5 vitamins, 2.0 mg dm^-3 2,4-D and 1.0 mg dm^-3 kinetin. Formation of cell clusters from the single cells was clearly noticed during ontogeny. Matured embryos at the cotyledonary stage were transferred to agar solidified medium for germination. The best conversion of embrya into plantlets (67.3 %) was recorded on media with half strength MS salts, B5 vitamins, 0.2 mg dm^-3 benzylaminopurine (BAP) and 0.2 mg dm^-3 gibberellic acid (GA₃). The plantlets were transferred to soil and hardened in the plastic pots. After proper acclimatization, the plantlets regenerated through somatic embryogenesis were compared to seed grown plants to observe any variation.

The experiment was conducted to identify the response of three cultivars of okra [Abelmoschus esculentus (L.) Moench] to exogenous hormones [gibberellic acid-(GA₃) and prohexadione-Ca] applied as foliar spray. Stem and leaf dry masses and stem length were significantly enhanced by the application of exogenous GA₃, but prohexadione-Ca inhibited growth. Control and prohexadione-Ca treated okra plants took more time to bloom than did GA₃ treated plants. In the fruits of all the cultivars a decrease in fructose content was observed, while protein content remained almost unchanged after the application of the two growth regulators. The small changes in chlorophyll a fluorescence characteristics observed under prohexadione-Ca suggested a weakening of the photochemical processes near the photosystem 2 reaction centre. The lowering of ratio between maximum time to reach maximum fluorescence, F_m (T_max) and Area (sum of F_m-F_t for t = 0 to t = T_max) caused by GA₃ was probably due to the increase of Area rather than to changes in T_max.