Induction of both somatic embryogenesis and organogenesis in presence of thidiazuron is reported in peanut tissues. However the histological evidence of thidiazuron induced somatic embryogenesis was unclear. Thidiazuron triggered multiple shoot differentiation in the plumule of the embryos. Keeping in view the ability of thidiazuron to induce both organogenesis and embryogenesis in peanut tissues, experiments were conducted to define the pathway of morphogenesis in the plumule of rooted somatic embryos. On exposure to thidiazuron, projections appeared from the plumule. These projections closely resemble the somatic embryos. However histological examination revealed that these are caulogenic buds and not somatic embryos. In concurrence with the earlier reports on thidiazuron induced organogenesis it is concluded that this growth regulator induces organogenic response in peanut tissues.

Influence of boron on somatic embryogenesis in papaya (Carica papaya L.) cv. Honey Dew was investigated. Immature zygotic embryos were grown in the induction medium containing Murashige and Skoog basal salts, with B₅ vitamins, picloram (1 mg dm^-3) or 2,4-dichlorophenoxy acetic acid (2 mg dm^-3) and different concentrations of boric acid (30 to 500 mg dm^-3). Maximum somatic embryo initiation was observed at 62 mg dm^-3 boric acid irrespective of the growth regulator used. The cotyledonary stage somatic embryos were germinated on MS basal medium devoid of growth regulators. The regenerated plantlets were hardened under greenhouse conditions and transferred to field.

High-frequency regeneration of shoots was achieved at root region of seedlings of Robinia pseudoacacia L. cultured from seeds on medium supplemented with thidiazuron (TDZ, 1.0 μM). The roots of intact seedlings proliferated and formed a compact callus followed by differentiation of numerous shoots. Corresponding cultures on benzylaminopurine-containing medium exhibited much weaker response. Hypocotyl segments also formed shoots at a lower concentration of TDZ (0.1 μM). The shoots formed on TDZ-containing medium were well-developed and readily rooted on hormone-free medium. The obtained plants after acclimation in culture room survived after transfer to soil.

The salicylic acid-induced changes in the polypeptide patterns of barley (Hordeum vulgare L.) leaves have been analysed using two-dimensional gel electrophoresis. An optimized 2-D PAGE protocol was used and gave reproducible 2-D gels from leaf crude protein extracts with a high number of detected polypeptides. When applied for 24 h SA affected the expression of a number of soluble proteins. Most of them appeared to be down-regulated. Although no abundant expression of specific proteins was observed, we detected three polypeptides that were present only in SA-treated leaves.

A spontaneously embryogenic cell line of the coumarin producing angelica [Angelica archangelica (L.) subsp. archangelica] was established via callus formation from seedlings grown from sterilized seeds on semi-solid, hormone-free modified B5 medium. The cell line has retained its embryogenic capacity for 5 years. The highest coumarin production for the cell line after 3 weeks of cultivation was achieved in the medium containing 3.0 % sucrose. Jasmonic acid had no statistically significant effect on the biomass or coumarin production. The established embryogenic cell line could be stored using cryopreservation. Plantlets grown in an air-sparged bioreactor were transferred directly to soil and vermiculite, and 63 % of them grew to maturity through two growth seasons. The coumarin content in the regenerated plants was comparable to that in wild plants. Thus this cell line could be used for in vitro propagation.

The regeneration of European linden (Tilia × europaea L.) in vitro was successful. When using axillary buds as primary explants it was possible to induce a new shoot growth. The highest number of shoots per explant (2.13 ± 1.09) was recorded at the presence of 0.2 mg dm^-3 6-benzylaminopurine. Up to 50% of elongated shoots rooted in the presence of 2.0 mg dm^-3 α-naphthaleneacetic acid.

A micro-propagating system based on the young stem node segments of Sophora flavescens Ait. (Fabaceae) was established. Murashige and Skoog (MS) basal medium supplemented with 8.88 μM 6-benzyladenine (BA) plus 2.69 μM α-naphthalene acetic acid (NAA) and that with only 5.37 μM NAA were found the best in promoting proliferation of shoots and induction of root, respectively. Percentages of shoot induction and number of shoot per explant were up to 93.4 % and 4.2 and rooting rate to 82.4 %, respectively. The segments of the regenerated shoots could be continuously induced to reproduce new shoots through subculture on the same medium in 30-d intervals and still kept this activity after being subcultured for 6 generations. After the regenerated plantlets were transplanted to field, they grew well, showing no any visible abnormalities.

The cyanobacterial crust occurring in desiccated state exposed to high temperature and solar radiation on the rock surface contained several low molecular mass (LMM) proteins (10.5, 13, and 25 kDa), water stress protein (wsp, 39 kDa), additional proteins (43 and 49 kDa), a chaperonin (58 kDa), and a stress-induced protein (84 kDa). When the crust was exposed to UV-C radiation, it counteracted the UV-B damage by overproduction of certain proteins and synthesis of two high molecular mass (HMM) proteins. Exposure of the crust to heat had an adverse effect on the survival of the organism there-in which was due to repression of few proteins. Unlike the modification pattern of protein synthesis in the cyanobacterium inhabiting the crust, the same organism grown in culture could tolerate heat by synthesizing two HMM proteins. Several proteins of diverse groups were repressed in the cyanobacterium in culture upon exposure to UV-C, which was counteracted by induction of three new polypeptides (chaperonin and HMMs), and overproduction of one 41 kDa protein.

The effect of exogenous brassinosteroids (BR) on the flowering induction of Pharbitis nil was examined. Generally plants treated with brassinolide and castasterone form less number of flowers than control plants, but degree of flowering inhibition was depended on the concentration and the method of BR application as well as the length of the inductive dark period. In plants regenerated from sub-induced apices treated with brassinolide at concentration of 1 and 10 μM the flower formation was inhibited completely.

Multiple shoots were initiated from nodal and shoot tip explants collected from mature trees of Morus alba L. cultivars Chinese White, Kokuso-27 and Ichinose, and M. multicaulis Perr. cultivars Goshoerami and Rokokuyaso after 2 weeks of culture. Nodal explants were more responsive than shoot tip explants. Murashige and Skoog basal medium was found to be most suitable medium and 6-benzylaminopurine was the most effective cytokinin for shoot induction. Explants collected between April and September evoked better response than the explants collected between October and March. Shoots were multiplied by transferring nodal explants excised from in vitro raised shoots onto a medium containing cytokinins. Sucrose was the most suitable carbon source examined for shoot multiplication. An increase in shoot multiplication rate was noticed upto 4 - 5 subcultures. Nodal explants rooted on an auxin-supplemented medium. The acclimatized plants were successfully transplanted in the field.

Leaves from mature in vitro grown plants of Drosera spathulata Labill. regenerated new plantlets on solid induction medium in light. Especially vascular sheath parenchyma cells located close to basal part of tentacule showed high embryogenic potential. Proembryoids arrising from the tentacule base part were visible by scanning electron microscopy. Their surface cells were linked and covered with thin external, fibrilar network representing an extracellular matrix (ECM). Proembryogenic surface cells were later connected by coarse strands of fibrils. Young protoderm was formed arround globular embryoids and its cells were characterized by "brain-like" surface structure. However, the surface of fully developed protodermal cells was practicaly smooth and cells were stick to each other very tightly in torpedo and cotyledonary shaped embryoids. The presence of ECM was typical only for somatic proembryos and globular embryos. The ECM network was never observed on the surface of heart and torpedo shaped embryos.

Somatic embryogenesis was achieved from mature embryos excised from stored hybrid Abies alba × Abies cephalonica seeds. Embryogenic tissue formation occurred on SH medium supplemented with 1 mg dm^-3 benzyladenine. The formation of embryogenic tissue was influenced by the time of storage of seeds. Initiation frequencies 27.2 - 29.0 % were obtained in embryos isolated from 6 month and 1 year stored seeds. Embryos excised from 4-year stored seeds showed no response. Embryogenic structures appeared on the surface of hypocotyl. They originated without previous callus formation. Embryogenic tissues were maintained in long-term cultures. After maturation treatment cotyledonary somatic embryos developed and germinated in small plantlets.

The induction of secondary somatic embryogenesis in Abies numidica De Lann. was achieved. Precotyledonary, cotyledonary, and desiccated cotyledonary embryos were used as explants. Cotyledonary embryos before desiccation were the most suitable. The most beneficial was induction medium Schenk and Hildebrandt (SH) with 1 mg dm^-3 thidiazuron and 1000 mg dm^-3 myo-inositol. Initiation frequency was from 1 to 34 %. Maturation of somatic embryos was achieved on modified Murashige and Skoog medium supplemented with 40 g dm^-3 maltose, 100 g dm^-3 polyethylene glycol-4000 and 10 mg dm^-3 abscisic acid. Mature somatic embryos after three weeks of desiccation germinated on SH medium with 10 g dm^-3 charcoal and 10 g dm^-3 sucrose.

Developmental changes and effects of various abiotic stresses on peptidyl prolyl cis-trans isomerase (PPIase) activity were studied in the seedlings of sorghum [Sorghum bicolor (L.) Moench cv. CSH-6]. The PPIase activity of sorghum seedlings markedly decreased after two days of germination. Up to 90 % of the PPIase activity was inhibited by cyclosporin-A. Maximal increase in specific PPIase activity in the 3-d-old seedlings was observed in response to osmotic stress and it was transient in nature. The stress-induced enhancement in PPIase activity, depending upon tissue and stress treatment, was due to induction of cyclophilins as well as other PPIases. Osmotic stress-induced enhancement in PPIase activity in the drought susceptible cv. SPRU-94008B was maximal in roots, as compared to shoots in the drought tolerant cv. ICSV-272.

The relationship between nutrient composition, crop biomass, and glutamate dehydrogenase (GDH) isoenzyme pattern was investigated in soybean (Glycine max) and maize (Zea mays) by monitoring the nutrient induced isomerization of the enzyme from the seedling stage to the mature crop. GDH was extracted from the leaves of the plants, and the isoenzymes were fractionated by isoelectric focusing followed by native polyacrylamide gel electrophoresis. The isomerization V_max values for soybean GDH, similar to maize GDH increased curvilinearly from 200 - 400 μmol mg^-1 min^-1 as the inorganic phosphate nutrient applied to the soil decreased from 50 - 0 mM. In soybean, combinations of N and K, P, or S nutrients induced the acidic and neutral isoenzymes, and gave biomass increases 25 - 50 % higher than the control plant. GDH isoenzymes were suppressed in soybean that received nutrients without N, K, or P and accordingly the biomass was about 30 % lower than the control. Treatment of maize with NPK nutrients increased the GDH V_max values from 138.9 at the vegetative to 256.4 μmol mg^-1 min^-1 at the reproductive phase, and suppressed the basic isoenzymes, but induced both the acidic and neutral isoenzymes thereby inducing seed production (27.0 ± 1.4 g per plant); whereas both the acidic and basic isoenzymes were suppressed in the control maize, and seeds did not develop. Simultaneous induction of the acidic, neutral, and basic isoenzymes of GDH indicated the occurrence of senescence. Therefore in maize and soybean, the induction of the acidic and basic isoenzymes of GDH led to the enhancement of biomass.

Mature zygotic embryos of Paspalum scrobiculatum L. cv. PSC 1 on MS or N₆ nutrient medium supplemented with various concentrations of 2,4-D (4.5 - 22.5 µM) formed embryogenic callus, which differentiated into somatic embryos within 5 weeks of culture. The somatic embryos after transfer to hormone-free regeneration medium germinated and formed plantlets. Of the two nutrient formulations, N₆ was relatively better than MS for somatic embryogenesis. A culture for 11 d on 100 µM 2,4-D was essential for the establishment of an embryogenic callus. Shorter duration, 4-d or 7-d culture on 2,4-D medium, supported some proliferation and subsequent differentiation into shoot-buds or multiple-shoots, in high-frequency cultures. This is first instance in monocots of a controlled regeneration response; either somatic embryogenesis or shoot formation.

Rootstocks for sweet cherry (Prunus canescens Bois) Camil GM 79 were grown in vitro on Murashige and Skoog (MS) medium, and on MS medium with double- and half-strength macroelements. All the media contained 4.4 μM 6-benzyladenine, 0.5 μM α-naphthylacetic acid, 0.3 μM gibberellic acid, 20 g dm^-3 sucrose and 7 g dm^-3 agar. The chemical analyses were monitored on day 0 and 40 of culturing in callus, stem and leaves. Fresh and dry mass of shoots increased linearly up to the end of culture. The highest fresh and dry masses and also the content of Ca and Mg were registered in shoots grown on half-strength MS medium.

ATPase activity was studied in calli from olive (Olea europaea L.) petioles cultured in media modified in their auxin/cytokinin ratio in order to induce different morphogenetic responses. Addition of 0.54 µM α-naphthaleneacetic acid (NAA) or 14 µM zeatin (ZEA) did not induce any morphogenesis in calli and proton pump activity in vivo was very low, while calli produced roots at 27 or 11 µM NAA + 0.28 µM ZEA and possessed clearly detectable proton pump activity. ATPase activity associated with microsomes isolated by differential centrifugation from different callus cultures had the same pH optimum and similar sensitivity toward nitrate and azide. However, microsomes isolated from non-morphogenetic calli had higher specific ATPase activity which was very poorly (6 %) inhibited by vanadate. Also, the fractionation of these microsomes on a continuous sucrose gradient showed two peaks of ATPase activity, the more pronounced one co-purifying with the Golg i marker enzyme, Triton-stimulated UDPase activity, suggesting thus the presence of very high ATPase activity in Golgi secretory vesicles. On the contrary, ATPase activity of microsomes from calli producing roots was more sensitive to vanadate (30 - 40 % inhibition). Furthermore, the component of ATPase activity attributable to Golgi secretory vesicles was less abundant.

High frequency shoot regeneration from cotyledons excised from 4-d-old seedlings of Brassica campestris L. cv. M 27 and Brassica juncea (L.) Czern. cv. Pusabold was achieved on Murashige and Skoog's (MS) medium supplemented with 1.0 mg dm^-3 N⁶-benzyladenine (BA) and 3 % (m/v) saccharose. Rooting occurred simultaneously with shoot formation on the medium containing 1.0 mg dm^-3 BA and 0.5 mg dm^-3 1-naphthaleneacetic acid. Cultures of cotyledon, cotyledon derived non-differentiating calli and differentiated calli with shoots and/or roots were analysed at different intervals for isozyme patterns of esterase and peroxidase. With the BA-induced development of shoot and/or root from non-differentiating callus, some conspicuous isozymes appeared which indicates the involvement of these isozymes in root and shoot development rather than in induction of morphogenesis in callus.

In vitro response of six tomato genotypes to different copper concentrations was studied. Cu was toxic to tomato explants at a relatively high concentration (100 µM), which reduced callus growth and shoot regeneration. Peto-86 followed by UC-97-3 were more tolerant to copper than the other genotypes. Cu (100 µM) induced the synthesis of eight new proteins (70.86 - 14.78 kD) in Peto-86 and six in Western Improve (46.43 - 14.78 kD) and UC-97-3 (77.69 - 14.78 kD). Cu-stress reduced the expression of some enzymatic bands of alcohol dehydrogenase and esterase, meanwhile, one peroxidase band at the locus Prx-1 was newly expressed under Cu-treatment.

The cloning of a 465 bp fragment from the 5'-flanking region of the gene encoding a cytosolic cyclophilin from periwinkle was achieved through inverse polymerase chain reaction. The DNA fragment was fused to a gusA-intron marker then introduced into tobacco by Agrobacterium tumefaciens-mediated transformation. Histochemical analysis of the transgenic shoot cultures demonstrated that the construct was able to drive GUS expression in stomata guard cells, but not in mesophyll cells when shoots were still attached to the callus from which they were initiated. In separated transgenic shoots and in seedlings, GUS was expressed in external and internal phloem and root hairs, respectively. GUS activity in transgenic tobacco seedlings was also investigated by fluorimetric assays. Treatments with NaCl or ABA decreased promoter activity whereas treatment with yeast extracts increased it.

Treatment of rose shoots with 50 µM acibenzolar-S-methyl (BTH) resulted in increased protection against Diplocarpon rosae. This was accompanied by the induction and accumulation of a set of extracellular proteins as shown by SDS-PAGE and 2D-PAGE. Some of these proteins have been identified as PR-1, PR-2, PR-3 and PR-5 proteins by immunoblot analysis probed with tobacco antisera against PR-1c, PR-N, PR-Q and PR-S protein. Most of the extracellular proteins activated by BTH were also induced and found to accumulate in leaves upon infection with Diplocarpon rosae. However, their accumulation was much more pronounced in BTH-pretreated leaves than in water-pretreated leaves upon a challenge inoculation with D. rosae, particularly, the 15 kD PR-1, 36 and 37 kD PR-2 proteins. They may be more important in the expression of disease resistance.

Plants were in vitro regenerated from leaf callus of Desmodium affine and D. uncinatum. Leaf explants were induced to form callus when aseptically cultured on Murashige and Skoog medium (MS) supplemented with 6 mg dm-3 6-benzylaminopurine (BAP) in combination with 1 mg dm-3 naphthaleneacetic acid (NAA). Regeneration of shoots was induced when callus was cultured on MS medium supplemented with 6 mg dm-3 BAP and 0.01 mg dm-3 NAA. Roots regenerated in high frequency when differentiated shoots were subcultured on MS medium supplemented only with 0.01 mg dm-3 NAA. The regenerated plantlets were successfully grown in pots. Calli from D. incanum failed to regenerate shoots.

The morphological and anatomical aspects of direct and indirect somatic embryogenesis in pea were described. Direct embryos were induced from shoot apical meristems of 3 to 5-d-old pea seedlings, embryogenic callus originated from immature pea zygotic embryos or shoot apices. Auxin (picloram, 2,4-dichlorophenoxyacetic acid) was necessary to induce somatic embryos. The developmental stages typical for pea zygotic embryos were detected. Globular and heartshaped somatic embryos were morphologically similar to their zygotic counterparts; in contrast, torpedo and cotyledonary somatic embryos displayed great morphological variation, which affected mainly cotyledons (size, shape, number). Based on anatomical sections, possible ways of somatic embryo formation and localization of initiation sites within primary explant tissue have been proposed. The multicellular origin of somatic embryos is supposed in both systems of pea somatic embryogenesis under investigation.

Eryngium foetidum L. plants were regenerated from mature leaf and petiole explants through direct organogenesis without intervening callus phase. From leaf explants, adventitious multiple shoots raised on Murashige and Skoog (MS) medium supplemented with 4.43 μM benzylaminopurine (BAP) and 0.57 μM indole-3-acetic acid (IAA), whereas in petiole explants shoot regeneration occurred at 8.86 μM BAP and 0.57 μM IAAA. 80% of the leaf explants and 44% of petiole explants produced shoots after four weeks of culture. The regenerated plants were rooted on MS medium supplemented with 2.46 μM indole-3-butyric acid and 2.88 μM gibberellic acid. The plants were successfully established in the soil and showed 70.9% survival in the field.

The effect of brassinosteroids (BRs) on catalase (EC 1.11.1.6), peroxidase (EC 1.11.1.7) and superoxide dismutase (SOD, EC 1.15.1.1) activity in tomato leaf discs was analyzed at 25 and 40 °C. Tomato leaf discs were preincubated for 24 h in Petri dishes with 24-epibrassinolide (EBR) or a polyhydroxylated spirostanic analogue of brassinosteroids (MH5). Both concentrations (10.60 and 2.12 nM) of EBR and MH5 stimulated the activity of SOD at 25 and 40 °C, the MH5-stimulated increase of this enzyme activity was greater. Peroxidase activity was unaffected at 25 °C, while at 40 °C this activity was enhanced by both compounds. The changes in catalase activity markedly depended on the structure BRs, doses and temperature. The results suggest a possible role of EBR and MH5 in the reduction of cell damage produced by heat stress due to induction of enzymatic antioxidants.

Transient expression of β-glucuronidase (GUS) in zygotic embryo axes of two cotton (Gossypium hirsutum L.) cultivars NHH-44 and DCH-32 was induced by Agrobacterium mediated transformation or by particle bombardment. For Agrobacterium transformation, disarmed A. tumefaciens strain GV 2260/p35SGUSINT was used. In cv. NHH-44, the maximum frequency of transient expression (14.28 %) was achieved on spotting Agrobacterium paste on the apical regions of the split embryo axes. The method resulted in a transformed callus line, which showed strong GUS activity. Integration of NPTII gene was confirmed by Southern analysis. Transgene expression by particle bombardment was achieved with p35SGUSINT and pIBGUS plasmids independently. The maximum frequency of GUS expression in 29.16 % explants was observed in cultivar NHH-44 with gold microcarriers (1.1 µm) when bombarded once with rupture disc of 7586 kPa at target cell distance of 6 cm. A transformed callus line was obtained when explants were bombarded with p35SGUSINT and cultured on Murashige and Skoog's medium supplemented with B₅ vitamins, 0.1 mg dm^-3 1-phenyl-3-(1,2,3-thiadiazol-5-yl) urea, 0.01 mg dm^-3 α-naphthaleneacetic acid, 3 % glucose + 50 mg dm^-3 kanamycin. High GUS activity was observed in callus tissue as well as in somatic embryo like structures achieved in liquid shake cultures.

Differential display of mRNA has been recently developed as a tool to detect and characterize changes in gene expression. We applied this technique to fruit trees plantlets induced to root in vitro, in order to isolate and study genes involved in root induction. A reproducible pattern of polymerase chain reaction (PCR) products was obtained, both in almond and apple, in vertical polyacrylamide gels stained with ethidium bromide. Differences in PCR fingerprinting were detected in mRNAs of basal part of either auxin induced or non induced microcuttings. Thus, we suggest that this technique can be used in woody species to detect changes among mRNA populations during root induction.

The first step during shoot primordia development in Papaver somniferum L. was the differentiation of globular meristemoids, resulting from localized cell division in callus tissue. During meristemoid maturation differences observed were in mitotic activity, cytoplasmic density, starch distribution, and in cell size, cell shape, and nucleus size to cell size ratio between peripheral and central meristemoid cells. Cell specialization within the meristemoids is a prerequisite for shoot primordia development.

We obtained transformed bean shoots by electroporation of intact bean cells with the plasmid pDPG165 containing bar gene conferring herbicide resistance to plants. Transformed shoots were selected from electroporated callus on herbicide containing media. Data of molecular analysis (PCR and Southern blotting) confirmed the insertion of bar gene in the genome of herbicide resistant shoots. Detailed procedures for obtaining regenerative bean callus, optimization of electroporation of intact cells and transgenic shoots are given.