This study was conducted to determine the reciprocal effects for anther culture response in wheat (Triticum aestivum L.) using a set of 4 × 4 full diallel crosses. Both reciprocal and nuclear genetic effects were highly significant for anther culture response and useful for selection and breeding purposes. General combining ability (GCA) effects were predominant for all investigated anther culture traits. Also, significant differences for specific combining ability (SCA) effects were detected between reciprocal crosses. Although significant reciprocal differences for responding anther, callus number and green plant regeneration were recorded in some reciprocal crosses, there were no significant reciprocal differences for albino plant regeneration. The use of one parent as male or female could lead to change at the production of green plants from the F₁ hybrids and screening of inbred lines for response to anther culture, without reciprocal effects, could decrease the utilization of breeding material.

Two vacuolar green fluorescent proteins (GFP) were stably inserted in Nicotiana tabacum and Nicotiana benthamiana genome, with unexpected difficulties, and compared with A. thaliana cv. Wassilewskaja transgenic plants expressing the same constructs. GFP fluorescence was strong in all tissues of A. thaliana but it was barely visible in Nicotiana. Confocal microscopy analysis revealed a variable distribution of the marker in those cells where GFP fluorescence was visible. The role of light dependent proteases was the variable pointing out more inter-species diversity. GFPs degradation was much higher in Nicotiana spp. than in A. thaliana. The version of GFP used appeared not to be a good vacuolar marker for Nicotiana differentiated tissues, although it can efficiently label vacuoles in protoplasts or calli. Nevertheless the sensitivity of the reporter protein can be used as an indicator of hidden characteristics of the plant vacuoles, revealing differences otherwise invisible. One of the markers in our system, GFP-Chi, evidenced a clear morphological difference in the vacuolar system of guard cells of the three species.

To further optimize a culture medium for induction of direct embryo formation of Oncidium cvs. Gower Ramsey and Sweet Sugar, five kinds of carbon sources, cellibiose, fructose, glucose, maltose and sucrose at 10, 20, 30 and 60 g dm^-3 were tested in this study. Cellibiose supply had an inhibitory effect and resulted in high percentage of explant browning in both cultivars. By contrast, fructose, glucose and sucrose were all effective for direct embryo induction. In cv. Gower Ramsey, the suitable ranges of concentration were found at 30-60 g dm^-3 of sucrose, 10-20 g dm^-3 of glucose and 20-30 g dm^-3 of fructose, respectively. The suitable ranges for cv. Sweet Sugar were at 20-60 g dm^-3 of sucrose, 10-30 g dm^-3 of glucose, 10-20 g dm^-3 of fructose and 30-60 g dm^-3 of maltose, respectively. The highest amount of embryos was obtained at 30 g dm^-3 of sucrose for cv. Gower Ramsey and at 20 g dm^-3 of glucose for cv. Sweet Sugar.

Effect of plant growth regulators, explant size, season of explant collection, temperature (20, 25 and 30 °C) and photoperiod on in vitro lotus (Nelumbo nucifera Gaertn.) shoot formation and growth were examined. Shoots formation was greatly influenced by growth regulators, explant size and season of explant collection. The maximum number of shoots were induced from bud explants on Murashige and Skoog (MS) medium containing 4.44 µM benzyladenine (BA) + 0.54 µM α-naphthalene acetic acid (NAA). Explants formed by bud of one expanded and one unexpanded leaf, which was collected in spring gave encouraging results of shoot production. Higher temperature favoured shoot induction and subsequent growth was much better at 25 °C compared to that at 20 and 30 °C.

Immature and mature zygotic embryos were used as source of explants for induction of somatic embryogenesis in Araucaria angustifolia. Embryogenic cultures (EC) were only obtained from immature zygotic embryos. Basic medium, carbon source, and genotype showed a significant influence on the formation of stage I somatic embryos (SE). When EC were submitted to maturation conditions, SE continued their individual development until stage II, but mature embryos were not obtained. Proteins secreted by embryogenic cultures were, to a certain degree, genotype specific and included an extracellular class IV chitinase and β-1-3-glucanase.

Total protein patterns were studied in the course of development of pea somatic embryos using simple protocol of direct regeneration from shoot apical meristems on auxin supplemented medium. Protein content and total protein spectra (SDS-PAGE) of somatic embryos in particular developmental stages were analysed in Pisum sativum, P. arvense, P. elatius and P. jomardi. Expression of seed storage proteins in somatic embryos was compared with their accumulation in zygotic embryos of selected developmental stages. Pea vegetative tissues, namely leaf and root, were used as a negative control not expressing typical seed storage proteins. The biosynthesis and accumulation of seed storage proteins was observed during somatic embryo development (since globular stage), despite of the fact that no special maturation treatment was applied. Major storage proteins typical for pea seed (globulins legumin, vicilin, convicilin and their subunits) were detected in somatic embryos. In general, the biosynthesis of storage proteins in somatic embryos was lower as compared to mature dry seed. However, in some cases the cotyledonary somatic embryos exhibited comparatively high expression of vicilin, convicilin and pea seed lectin, which was even higher than those in immature but morphologically fully developed zygotic embryos. Desiccation treatments did not affect the protein content of somatic embryos. The transfer of desiccated somatic embryos on hormone-free germination medium led to progressive storage protein degradation. The expression of true seed storage proteins may serve as an explicit marker of somatic embryogenesis pathway of regeneration as well as a measure of maturation degree of somatic embryos in pea.

The changes in nuclear ultrastructure during garlic development were investigated. In quiescent cells, the nucleus was oblate and small, full of heterochromatin, and without nucleolus. In the active phase cells, the nucleus moved toward the center of the cell, and was enlarged with many deep fissures, and the heterochromatin in the nucleus turned to be euchromatin. One or more nucleoli were seen in active phase cells. Cell divisions were by means of amitosis. Relatively large nuclei with small distortions were seen in the callus cells. These results suggest that the metabolism of the active cells was higher than that of callus and quiescent cells.

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.

Embryogenic, friable and small (ca. 3 mm) calli showed optimum gus expression and were best suited for selection during genetic transformation of rice through particle bombardment. Through prolonged culture of mature seeds on original callus induction medium, this type of calli could be produced in large numbers across several elite rice genotypes. To minimize the non-transformed escapes 50 mg dm^-3 hygromycin and 8 mg dm^-3 glufosinate ammonium were found to be critical during selection. Addition of selection marker during regeneration was essential. Regular and frequent (every 15 d) transfer of calli to fresh selection medium for three cycles was also important. A simple and economic procedure for screening large number of putative resistant plants was described.

A protocol was developed for direct differentiation of multiple shoot buds from leaf explants of Cajanus cajan. In a modified Murashige and Skoog's medium supplemented with 2.22 µM benzyladenine (BA), 0.57 µM indole-3-acetic acid (IAA) and 41 µM adenine sulphate (AdS), the segments of basal halves of the first two leaves of a young seedling incubated on filter paper bridges in liquid medium took 20 - 25 d to differentiate shoot buds. The explants after transfer to solidified medium, with lower concentration of BA (0.22 μM) resulted in fast growing healthy shoots. The developed shoots (measuring ca. 3 cm) were rooted in a medium supplemented with 1.42 µM IAA. They were subsequently grown in pots with soil with more than 80 % transplantation success.

The shoot fresh mass, root length and root numbers of two potato (Solanum tuberosum L.) cultivars Favorita and Helanwuhua were increased significantly by the application of 0.2 - 2 mg dm^-3 jasmonic acid (JA) in the Murashige and Skoog medium. However, the growth of potato explants was inhibited by JA at high concentrations (20 - 50 mg dm^-3). Chlorophyll content in explant leaves decreased with an increase in the concentration of JA. In leaves treated with 0.2 mg dm^-3 JA acid peroxidase activity increased, while in the leaves treated with more than 2 mg dm^-3 JA peroxidase activity decreased. Under the dark, the microtuber numbers, fresh mass and percentage of big microtubers of two potato cultivars were not promoted by the application of 0.2 - 50 mg dm^-3 JA.

Shoot apices of Pinus roxburghii Sarg were cultured on Murashige and Skoog's medium (MS) supplemented with cytokinins [6-benzyladenine (BA), kinetin and N-benzyl-9-(2-tetrahydropyranyl) adenine (BPA)] alone and in combination with auxin, α-napthaleneacetic acid (NAA). Of the three cytokinins tested at varying concentrations, medium supplemented with 10 µM BA was found optimal in respect of explant responsiveness (97.22 %) and average number of buds induced per explant (7.42). The concentration of cytokinins in the induction medium had a profound effect on rate of elongation of induced buds on MS basal medium containing 0.5 % activated charcoal. Further, shoots induced on lower concentrations of BA increased up to 2.4 times in length in 4 weeks. Decapitation of the explant enhanced the rate of axillary bud elongation. Proliferating shoot cultures were established by sub-culturing the axillary shoots on MS supplemented with 10 µM BA. Shoots 2-3 cm in length were suitable for culturing as more buds were induced on them compared to longer or shorter shoots. Root primordia were induced on 70.83 % shoots when transferred to 1/2 MS medium supplemented with 5.0 µM NAA. Elongation of root primordia (60 %) was achieved in liquid 1/2 MS basal medium. The plantlets were successfully transferred to soil after hardening; the time period from initiation of shoot buds to transplantation being 20-22 weeks.

Plants of two cytotypes (2n=2x=20, and 2n=3x=30) of pinto peanut (Arachis pintoi Krapov. & W.C. Gregory) were regenerated through somatic embryogenesis. Embryogenic calli were induced from shoot tips or immature leaves dissected from in vitro growing plants. In the case of the diploid peanut the best somatic embryogenesis was achieved when shoot tips were cultured on Murashige and Skoog (MS) medium supplemented with 10 mg dm^-3 Picloram (PIC) and 0.1 mg dm^-3 6-benzylaminopurine (BAP) or when explants from immature leaves were cultured on MS + 10 mg dm^-3 PIC + 0.01 mg dm^-3 BAP. In the case of triploid peanut the highest number of somatic embryos was obtained when shoot tips were cultured on MS + 10 mg dm^-3 PIC + 0.01 mg dm^-3 BAP or when immature leaves were cultured on MS + 20 mg dm^-3 PIC + 0.01 mg dm^-3 BAP. Somatic embryos were converted into plants by culture on MS + 0.01 mg dm^-3 naphthaleneacetic acid + 0.01 mg dm^-3 BAP. Plants were successfully transferred to pots in greenhouse.

This study concerns the efficacy of partial agar substitution by galactomannans as support in plant regeneration media for Nicotiana tabacum. The production of multiple shoots from leaf-derived callus and their rooting were evaluated. The galactomannans applied were obtained from Cassia fastuosa (cassia) and Cyamopsis tetragonolobus (guar gum - a commercial galactomannan) seeds. The results obtained on media solidified with mixtures of agar/galactomannan (3 g dm^-3 each) gels were compared with those on media gelled with a standard concentration of agar (6 g dm^-3). The in vitro performance allowed to conclude that the use of galactomannans raised the number of shoots and improved their quality. Furthermore, the length of roots and the size of leaves were significantly higher in the media solidified with agar/guar galactomannan mixtures.

Ageing of plant organs is accompanied by an increased production of free radicals what results in membrane lipid peroxidation. Non-polar aldehydes originating from this process interact with the cellular material to form the fluorescent end-products, lipofuscin-like pigments (LFP). Their formation was studied both qualitatively and quantitatively in ageing of bean cotyledons. The concentration of lipofuscin-like pigments increased 9-fold in 14-d-old (senescent) cotyledons in relation to 8-d-old (young) cotyledons. HPLC fractionation patterns indicate changes in their composition during ageing. The LFP increase in old cotyledons was accompanied by elevated levels of non-polar aldehydes that increased during ageing to 167 %. The composition of aldehydes was studied by mass spectrometry. The most abundant fraction in both young and old cotyledon was represented by C12 aldehydes, which comprised both saturated and unsaturated species. We have observed differences in abundances of individual aldehydes between the young and the old cotyledons that might explain the differences in the composition of lipofuscin-like pigments. These results support the involvement of free radicals in plant ageing; however, it is suggested that plant aldehydic products of lipid peroxidation differ from those found in animals.

Regeneration of Plumbago rosea L., a rare medicinal plant, via somatic embryogenesis in callus cultures derived from leaf explants was described. Optimum callus formation was achieved on semi-solid Murashige and Skoog (MS) medium supplemented with 0.25 mg dm^-3 kinetin and 2.0 mg dm^-3 1-naphthaleneacetic acid (NAA). Somatic embryogenesis was achieved upon transferring the 4-week-old callus to a medium containing 1.0 mg dm^-3 kinetic (Kn), 0.5 mg dm^-3 gibberellic acid (GA₃) and 0.1 mg dm^-3 NAA. Embryo maturation and germination was achieved on the half-strength MS basal salts supplemented with 0.01 - 0.25 mg dm^-3 Kn and 2 % (m/v) saccharose. An average of 50 - 60 plantlets were obtained from 150 mg of embryogenic callus within 4 week of subculture. Out of the 50 plantlets about 28 survived in the greenhouse.

The endosperms of Carthamus tinctorius cv. HUS-305, excised at globular to heart-shaped stages of zygotic embryo development, were cultured on Murashige and Skoog's medium (MS) supplemented with different concentrations of 6-benzylaminopurine (BAP), kinetin, thidiazuron (TDZ), 2,4-dichlorophenoxyacetic acid (2,4-D) or α-naphthalene-acetic acid (NAA). The highest incidence of callusing was on 2,4-D supplemented media. However, embryos differentiated only from the calli developed on media supplemented with BAP, kinetin or TDZ with the last eliciting maximum embryogenic response. The addition of a reduced nitrogen source, casein hydrolysate to MS medium supplemented with BAP and/or NAA, did not stimulate the response. However, adenine sulphate (100 mg dm^-3) promoted the induction of somatic embryos. Upon transfer to MS basal medium or the same supplemented with 0.61 µM gibberellic acid (GA₃), plumular poles of few embryos elongated resulting in the development of shoots.

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 effects of NaCl on growth, contents of proteins and proline, and activities of catalase, peroxidase and polyphenol oxidase were investigated in seedlings and calli of Trigonella foenum-graecum L. and T. aphanoneura Rech. f. Seeds and hypocotyl explants were cultured on Murashige and Skoog medium supplemented with 0, 50, 100, 150 and 200 mM NaCl. Seed germination and the fresh and dry mass of the seedlings decreased significantly under salinity. In both species significant increases in protein content of seedlings over that of control were observed at 150 and 200 mM NaCl. Protein content in calli decreased at 200 mM NaCl over that of control. Protein content was higher in seedlings than in calli at all NaCl concentrations. Conversely, proline content was lower in seedlings than in calli at all the tested NaCl concentrations. NaCl caused changes in the activities of peroxidase, catalase and polyphenol oxidase in seedlings and calli.

The present study evaluated the effects of chilling, partial desiccation, cotyledon excision and successive subculture of microspore-derived embryos on plant development in oilseed rape (Brassica napus L.). The results showed that out of the five media, all the genotypes showed the best response when the embryos were cultured on the half-strength Murashige and Skoog medium with 2.0 mg dm^-3 benzylaminopurine. A cold treatment for 3 or 5 d further increased frequencies of embryo germination (90.0 %) and plantlet development (58.46 %). Desiccation for one day also increased the embryo germination and plantlet development in all genotypes tested. Cutting the cotyledons of the embryos at late cotyledonary stage significantly increased the frequency of plantlet development. The highest rate of plantlet development was obtained from cultures of embryos sampled with size of less than 4.0 mm. The successive subculture further improved the germination and development of plantlets from embryos. In the genotype ZJU452, the rate of plantlet development reached 99.78 % after the second subculture of embryos.

An efficient in vitro regeneration system in kumquats (Fortunella crassifolia Swingle) was established. Explant types and orientations, concentrations and combinations of plant growth regulators were evaluated for their influences on efficiency of plant regeneration. It was found that the optimum explant and its orientation was epicotyl planted vertically with upper part upward, and a shoot regeneration frequency of 1.48 shoots per explant was obtained on Murashige and Skoog (1962; MS) medium supplemented with 22.19 μM 6-benzyladenine (BA). A rooting percentage as high as 74 % was obtained on 1/2 MS supplemented with 0.54 μM 1-naphthaleneacetic acid (NAA), 9.29 μM kinetin (KN), and 0.5 g dm^-3 activated charcoal.

A cell culture system has been developed to examine a multicomponent defense response induced in grapevine (Vitis vinifera L. cv. Limberger) tissues by both biotic and abiotic elicitors. H₂O₂ from the oxidative burst, cell death, extracellular alkalinization, and defense responses such as the accumulation of defense-related proteins and expression of corresponding genes were analyzed in grapevine suspension cultures. Cultured cells responded differentially to a set of 14 elicitors. The most effective group of elicitors was represented by salicylic acid, chitosan, methyl jasmonate, and elicitor released from cell walls of phytopathogen Botrytis cinerea. These four representative elicitors highly stimulated accumulation of pathogenesis-related proteins and key enzymes of the phenylpropanoid pathway. Further, fungal elicitor caused rapid transcriptional activation of genes encoding diverse defense-related products. The expression kinetics of four defense-related genes (PR-1, PR-9, PAL, and CHI) were different and strongly dependent on the nature of elicitor used.

An efficient protocol has been developed for rapid micropropagation of Ocimum basilicum. Multiple shoots were induced by culturing shoot tip explants excised from mature plants on a liquid Murashige and Skoog (MS) medium supplemented with 5-100 µM of thidiazuron (TDZ) for different treatment duration (4, 8, 12 and 16 d). The optimal level of TDZ supplementation to the culture medium was 50 µM for 8 d induction period followed by subculturing in MS medium devoid of TDZ as it produced maximum regeneration frequency (78 %), mean number of shoots (11.6 ± 1.16) and shoot length (4.8 ± 0.43 cm) per explant. A culture period longer than 8 d with TDZ resulted in the formation of fasciated or distorted shoots. The regenerated shoots rooted best on MS medium containing 1.0 µM indole-3-butyric acid (IBA). The micropropagated shoots with well developed roots were successfully established in pots containing garden soil and grown in greenhouse with 95 % survival rate. The regenerated plants were morphologically uniform and exhibited similar growth characteristics and vegetative morphology to the donor plants.

Growth parameters and cadmium accumulation were investigated in alfalfa seedlings treated with 10 μM salicylic acid (SA) at the beginning of seed imbibition. Shoot and root growths were accelerated by SA treatment and suppressed by Cd both in presence and absence of SA. Cd accumulation was stimulated by SA in alfalfa seedlings in dependence of the treatment duration. K, Mg, Ca and Fe contents in roots are decreased in the presence of Cd alone, while SA induces a decrease of Mg, Ca and Fe. Shoot K, Mg and Ca concentrations are increased by Cd only in the absence of SA, while SA induces also an increase of these concentrations, but only in the absence of Cd. High negative correlation of Cd concentration with K and Ca concentrations in root indicates a competition for the same carrier not regulated by SA. Positive correlation between Cd and Mg concentrations in shoots, which is decreased by SA pre-treatment, together with the increase of positive correlation between Cd and Fe concentrations in shoots under the influence of SA, indicates a possible mechanism of SA action through maintenance of ionic homeostasis.

Dehydrins present a distinct biochemical group of late embryogenesis abundant (LEA) proteins characterised by the presence of a lysine-rich amino acid motif, the K-segment. They are highly hydrophilic, soluble upon boiling, and rich in glycine and polar amino acids. It is proposed that they can act as emulsifiers or chaperones in the cells, i.e., they protect proteins and membranes against unfavourable structural changes caused by dehydration. Cold usually precedes freezing in nature and induces many physiological and biochemical changes in the cells of freezing-tolerant plant species (cold-acclimation) that enable them to survive unfavourable conditions. It is demonstrated that the induction of dehydrin expression and their accumulation is an important part of this process in many dicotyledons (both herbaceous and woody species), and also in winter cultivars of cereals, especially wheat and barley. Some mechanisms which are proposed to be involved in regulation of dehydrin expression are discussed, i.e., endogenous content of abscisic acid, homologues of Arabidopsis C-repeat binding factor (CBF) transcriptional activators, the activity of vernalization genes and photoperiodic signals. Finally, we outline some new approaches emerging for the solution of the complex mechanisms involved in plant cold-acclimation, especially the methods of functional genomics that enable to observe simultaneously changes in the activity of many genes and proteins in a single sample.

The study presents the comparative analyses of endogenous contents of auxin (IAA), cytokinins (CKs), polyamines (PAs), and phenolic acids (PhAs) in apical and basal parts of elm multiplicated shoots with regard to the organogenic potential. The shoot-forming capacity was higher in the apical part than in the basal part. However, the timing of root formation was in the apical type of explant significantly delayed (compared with the organogenic potential of basal part). Significantly higher contents of free bases, ribosides and ribotides of isopentenyl adenine, zeatin and dihydrozeatin that were found in the apical segments, might be considered as the most important factor affecting in vitro shoot formation. The content of endogenous free IAA was approximately three times higher in the basal shoot parts than in the apical parts. The amounts of putrescine and spermidine were higher in the apical part which generally contains less differentiated tissues than the basal part of shoot. The predominant PhA in both types of explants was caffeic acid, and concentrations of other PhAs decreased in the following order: p-coumaric, ferulic, sinapic, vanillic, chlorogenic, p-hydroxybenzoic and gallic acids. The contents of all determined PhAs in their free forms and higher contents of glycoside-bound p-coumaric, ferulic and sinapic acids, precursors for lignin biosynthesis, were found in the basal parts.

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.

The nodal explants of in vitro shoots of Holarrhena antidysenterica L. were cultured on Murashige and Skoog's (MS) medium augmented with 15 μM N⁶-benzyladenine (BA) alone (control) or supplemented with different concentrations (1, 5, 10 and 20 mg dm^-3) of CdCl₂, CuSO₄, Pb(NO₃)₂ and ZnSO₄. The maximum morphogenic response in terms of average shoot number (4.95 ± 0.17) was seen in control. ZnSO₄ proved to be less inhibitory in comparison to CuSO₄, Pb(NO₃)₂ and CdCl₂. None of the explants cultured on CdCl₂ containing medium induced multiple shoots. Maximum protein content [3.80 ± 0.04 mg g^-1(f.m.)] was observed in control and slightly less [3.50 ± 0.02 mg g^-1(f.m.)] in tissues exposed to 1 mg dm^-3 of CuSO₄ and minimum [1.00 ± 0.02 mg g^-1(f.m.)] in Zn treated (20 mg dm^-3) explants. SDS-PAGE analysis of the treated tissues revealed that two new polypeptides (29 and 20 kDa) in response to Cu and Zn treatment, respectively, have been synthesized.

Rice (Oryza sativa L.) was grown in pots with pyridine N-oxide (PNO), 4-morpholino pyridine N-oxide (MNO), and sodium meta silicate as the sources for silicon. Aliquots of these were added in fortnightly intervals to seedlings through anthesis stage. The plants were monitored for plant growth characteristics, chlorophyll content (SPAD values), photosystem 2 activity (variable to maximum fluorescence ratio of dark adapted leaves), and for blast and yellow stem borer resistance. Deposition of silica in the leaves was monitored by scanning electron microscopy and silicon mapping. PNO or MNO application resulted in significant silicon accumulation in leaf bundle sheath cells. Application of PNO and MNO imparted disease and pest resistance by increasing silicon uptake of rice plants.

Embryogenic callus in Catharanthus roseus was initiated from hypocotyl on Murashige and Skoog's (MS) medium supplemented with 1.0-2.0 mg dm^-3 of 2,4-dichlorophenoxyacetic acid (2,4-D) or chlorophenoxyacetic acid (CPA). Calli from other sources were non-embryogenic. Numerous somatic embryos were induced from primary callus on MS medium suplemented with naphthalene acetic acid (NAA) within two weeks of culture. Embryo proliferation was much faster on medium supplemented with 6-benzylaminopurine (BAP). After transfer to medium with gibberellic acid (GA₃, 1.0 mg dm^{- 3}) mature green embryos were developed and germinated well into plantlets on MS liquid medium supplemented with 0.5 mg dm^-3 BAP. Later, embryos with cotyledonary leaves were subjected to different auxins treatments for the development of roots. Before transfer ex vitro, plantlets were cultivated on half strength MS medium containing 3 % sucrose and 0.5 mg dm^-3 BAP for additional 2 weeks. Additionally, the effect of liquid medium has been evaluated at different morphogenetic stages.