Showing papers in "Plant Cell Tissue and Organ Culture in 2000"

Effects of saline and osmotic stress on proline and sugar accumulation in Populus euphratica in vitro.

Abstract: The use of in vitro shoot cultures to evaluate osmotic and salt tolerance and the effects of salt and mannitol in the medium on proline and sugar accumulation were investigated in two poplar species, P. euphratica and P. alba cv. Pyramidalis × P. tomentosa. Shoot length, leaf number, whole plant dry weight, and the accumulation of proline and total soluble sugars in leaves were quantified after 2 weeks. All P. euphratica plantlets survived at all levels of mannitol and NaCl, while the mortality of P. alba cv. Pyramidalis × P. tomentosa increased both at the mannitol and the NaCl treatments. A significant increase in proline accumulation was observed in both young and mature P. euphratica leaves at 200 mM mannitol and above, and at 150 mM NaCl and above. The total soluble sugar content increased in young P. euphratica leaves at 250 mM NaCl; however, it decreased in the mature leaves. Similar increases of the total soluble sugar content were not seen in P. alba cv. Pyramidalis × P. tomentosa plants in response to either mannitol or NaCl treatment. Our results suggest that accumulated proline and sugars promote osmotic and salt tolerance. The effects of accumulated proline and total soluble sugars on leaves are discussed in relation to growth and osmotic adjustment.

In vitro micropropagation of Gymnema sylvestre - a multipurpose medicinal plant.

Abstract: The nature of the explant, seedling age, medium type, plant growth regulators, complex extracts (casein hydrolysate, coconut milk, malt extract and yeast extract) and antioxidants (activated charcoal, ascorbic acid, citric acid and polyvinylpyrrolidone) markedly influenced in vitro propagation of Gymnema sylvestre. A maximum number of shoots (57.2) were induced from 30 day old seedling axillary node explants on Murashige and Skoog (MS) medium containing 6-benzyladenine (1 mg l−1), kinetin (0.5 mg l−1), 1-napthalene acetic acid (0.1 mg l−1), malt extract (100 mg l−1) and citric acid (100 mg l−1). High frequency of rooting was obtained in axillary node explant derived shoots (50%) on half strength MS medium supplemented with IBA (3 mg l−1). The plantlets, thus developed, were hardened and successfully established in natural soil.

The effects of silver nitrate and different carbohydrate sources on somatic embryogenesis in Coffea canephora

Abstract: The response of five Coffea canephora Pierre genotypes with regard to somatic embryogenesis was tested on media containing silver nitrate (AgNO3) and different carbohydrates (sucrose, fructose, maltose and glucose). The presence of AgNO3 caused only small modifications to the ionic equilibrium of the media. At concentrations between 30–60 μM, AgNO3 improved embryo yield for the genotypes evaluated, while higher doses negatively affected the regenerative capacity. The substitution of maltose, glucose or fructose for sucrose produced different responses depending on the genotype. Fructose significantly increased somatic embryo production in genotypes N91 and N128, while maltose was highly effective for N75. In addition, more synchronous embryo development was observed in genotype N91 when glucose was used instead of sucrose.

Pilot-scale culture of adventitious roots of ginseng in a bioreactor system

Abstract: A pilot-scale culture of multiple adventitious roots of ginseng was established using a balloon-type bubble bioreactor. Adventitious roots (2 cm) induced from callus were cultured in plastic Petri dishes having 20 ml of solid Schenk and Hildebrandt (1972) medium containing 3% sucrose, 0.15% gelrite, and 24.6 μM indole-3-butric acid. An average of 29 secondary multiple adventitious roots were produced after 4 weeks of culture. These secondary roots were elongated on the same medium, reaching a length of 5 cm after 6 weeks of culture. A time course study revealed that maximum yields in 5-l and 20-l bioreactors were approximately 500 g and 2.2 kg at day 42 with 60 g and 240 g inoculations, respectively. Cutting twice during the culture increased the total amount of biomass produced. The root biomass in a 20-l balloon-type bubble bioreactor was 2.8 kg at harvest with 240 g of inoculum after 8 weeks of culture. The total saponin content obtained from small-scale and pilot-scale balloon type bubble bioreactors was around 1% based on dry weight. Inoculation of 500 g fresh weight of multiple adventitious roots into a 500 l balloon-type bubble bioreactor with cutting at 4 and 6 weeks after inoculation produced approximately 74.8 kg of multiple roots. The ginsengnoside profiles of these multiple adventitious roots were similar to profiles of field-grown ginseng roots when analyzed by HPLC.

Mass multiplication of protocorm-like bodies using bioreactor system and subsequent plant regeneration in Phalaenopsis

Abstract: Protocorm-like bodies (PLBs) formed on leaf segmentsin vitro were used as explants for bioreactor cultures. Continuous immersion cultures (air lift column and air lift-balloon bioreactor), and temporary immersion cultures (with or without charcoal filter attached) were used for the culture of PLB sections. A temporary immersion culture with charcoal filter attached was most suitable for PLB culture. About 18,000 PLBs were harvested from 20 g of inoculum (∼1000 PLB sections) in 2 l Hyponex medium after 8 weeks of incubation. Aeration in a bioreactor at 0.5 or 2.0 volume of air per volume of medium min−1 (vvm) yielded similar levels of biomass production. PLBs grown in bioreactors were cultured on solid Murashige and Skoog, Vacin and Went, Knudson C, Lindemann and Hyponex media. Hyponex medium was found to be suitable for conversion of PLBs into plantlets and 83% of PLBs transformed into plantlets on this medium. The feasibility of using PLBs for large-scale micropropagation was evaluated for scaled-up liquid cultures in bioreactors, rate of proliferation, and regeneration.

Somatic embryogenesis and plant regeneration of turf-type bermudagrass: Effect of 6-benzyladenine in callus induction medium

Abstract: In order to optimize tissue culture conditions for bermudagrass, an important warm-season turfgrass species, tissue culture responses of young inflorescences of a hybrid bermudagrass cultivar `Tifgreen' (Cynodon dactylon×Cynodon transvaalensis) and a common bermudagrass cultivar `Savannah' (Cynodon dactylon) were investigated. When cultured on Murashige and Skoog medium with 4.52 to 13.57 μM (1–3 mg l-1) 2,4-D, young inflorescence segments yielded non-embryogenic calli which were unorganized and had loosely associated, long tubular cells on the surface. However, inclusion of 6-benzyladenine (BA) in callus induction medium at a level of 0.044 μM (0.01 mg l-1) induced formation of a compact, nodular embryogenic structure on approximately 20% of the calli. Calli with such a compact embryogenic structure were highly regenerable. When young inflorescences smaller than 0.75 cm were cultured, the embryogenic structure yielded green plantlets with regeneration rates of 79.5% and 83.3%, respectively for the two cultivars. All 96 plants regenerated from calli induced in the BA-containing medium were green and morphologically normal. The embryogenic nature of the compact structure was confirmed by scanning electron microscopy.

Micropropagation of Hemidesmus indicus for cultivation and production of 2-hydroxy 4-methoxy benzaldehyde

Abstract: Caulogenic responses of various explant types from 12-month-old plants of Hemidesmus indicus were tested Second and third visible nodes (05 cm) from the apex and root segments (05 cm) were the most and least regenerative respectively, with the formation of 937 and 26 shoots in 4 weeks on half strength MS medium supplemented with 222 μM BA and 107 μM NAA and 444 μM BA and 269 μM NAA respectively Caulogenic ability of the nodes decreased with increasing maturity Shoot buds initiated upon the young nodes on day 10 developed into 72 cm long shoots within 4 weeks thereby making a shoot elongation phase unnecessary Nodal explants of the in vitro raised shoots subcultured in the same medium produced 932 shoots of 71 cm length in 3–4 weeks, similar to those of the mature plant-derived nodes Multiplication through subculture of the nodes up to 25 passages of 4 weeks each was achieved without decline Shoot cultures were rooted in quarter salt strength MS medium containing 98 μM IBA and the rooted plants were hardened for establishment in pots at 96% rate Four months after establishment, the micropropagated plants were stable and showed uniform morphological and growth characteristic After 12 months of cultivation in the field, on an average micropropagated plant consisted of 4–5 shoots, 5–8 branches per shoot and increased root biomass (135 g) compared to the poor growth (single shoot and 2–3 branches) and root production (46 g) values obtained with plants raised from conventional rooted stem cuttings The concentration of the root specific compound, 2-hydroxy 4-methoxy benzaldehyde per plant was 2–3 fold higher in micropropagated plants though on unit dry root biomass (012% per g dry wt) basis it remained the same between two sources of plants

Micropropagation of Centella asiatica (L.), a valuable medicinal herb

Abstract: A protocol is described for rapid and large-scale in vitro clonal propagation of the valuable medicinal herb Centella asiatica (L) by enhanced axillary bud proliferation in nodal segments isolated from mature plants Although bud break was dependent on BA supply, the synergistic combination of 222 μM BA and 268 μM NAA induced the optimum frequency (91%) of shoot formation as well as shoot number (4 to 5 shoots per node) Subculturing of nodal segments harvested from the in vitro derived axenic shoots on the multiplication medium enabled continuous production of healthy shoots with similar frequency MS medium supplemented with 67 μM BA and 288 μM IAA was found most suitable for shoot elongation Rooting was highest (90%) on full-strength MS medium containing 246 μM IBA Micropropagated plants established in garden soil were uniform and identical to the donor plant with respect to growth characteristics This micropropagation procedure could be useful for raising a stock of genetically homogenous plant material for field cultivation

Callus formation and plant regeneration from Hypericum perforatum leaves

Abstract: Use of Hypericum perforatum L. has increased in the past few years due to the antidepressant and antiviral activities found in extracts of this plant. As a result of its potential as a pharmaceutical, a new system was developed for in vitro culture of this species. Leaf explants were inoculated onto MS medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D, 0.45 or 4.5 μM) and 6-benzyladenine (BA, 0.44 or 4.4 μM) or kinetin (0.46 or 4.6 μM). Explants were cultivated under dark or light conditions to induce callus formation. Callus initiation was observed in all media evaluated and the highest cell proliferation was obtained from explants cultivated in the presence of 4.4 μM BA and 4.5 μM 2,4-D in the dark. Shoot induction was obtained from callus induced on 4.6 μM kinetin and 0.45 μM 2,4-D 6 weeks after transferring the callus to a MS medium supplemented with 4.4 μM BA. Roots were induced from shoots on full and half-strength MS media with or without indolebutyric acid (IBA, 4.9 μM) and the highest rooting frequencies were obtained on half-strength MS medium, regardless of the presence of IBA. Regenerated plants were easily acclimated in greenhouse conditions. The procedure reported here allows the micropropagation of H. perforatum in five months of culture and the proliferation of cell masses which could be used for studies on organic compounds of pharmaceutical interest.

In vitro multiplication and ecorehabilitation of the endangered Blue Vanda

Abstract: Rapid multiplication of endangered Vanda coerulea Griff ex. Lindl. (Orchidaceae) was achieved through culture of shoot tips of mature plants, shoot tips and leaf bases of 8-month-old axenic seedlings on Mitra et al. (1976) medium supplemented with 10% coconut water, 500 mg1-1 casein hydrolysate and a combination of 8.8 μM benzyladenine and 4.1 μM napthaleneacetic acid (NAA). Shoot tips (0.5 – 0.8 cm) cultured in both agar and agitated liquid media responded alike with direct formation of 3–12 shoot buds in 12 weeks, while callus-free formation of 3–8 protocorm-like bodies (PLBs) in 4–8 weeks was noticed in seedling leaf base segments (1.0–1.5 cm). Formation of new buds or PLBs, rapid growth of buds into shoots and emergence of shoots from PLBs occurred when the explants with proliferating buds / PLBs were subcultured in medium enriched with 35 g 1-1 banana pulp, 30% coconut water and 1.08 μM NAA. A maximum of 70 and 100 shoots of varied length were obtained from a single shoot tip/leaf base explant after 30 weeks of culture. Rooting of shoots (3.0–4.0 cm) occurred in medium containing 35 g 1-1 banana pulp and 1.08 μM NAA within 3–4 weeks. Rooted plants were established easily (95–100%) in community pots without hardening. The regenerated plants were cytologically stable (2n = 38). They were free from morphological, growth and flowering abnormalities. Eighty-five community potted plants were reintroduced into alien forest habitats at Ponmudi and Palode in southern ranges of the Western Ghats. They established at 70–80% rate.

Direct shoot regeneration from node, internode, hypocotyl and embryo explants of Withania somnifera

Abstract: In vitro studies were initiated with Withania somnifera (L.) Dun. for rapid micropropagation of selected chemotypes using nodes, internodes, hypocotyls and embryo explants. Direct regeneration of shoot buds was observed in MS basal medium supplemented with various concentrations of either benzyladenine (BA) or thidiazouron (TDZ) depending on the explant. Nodal explants formed multiple shoots both from pre-existing and de novo buds on Murashige and Skoog's medium (MS) containing 0.1–5.0 mg l−1 BA and a ring of de novo shoot buds on MS medium containing 0.2 and 0.3 mg l−1 TDZ. Internodal explants formed shoot buds on MS with 1.0 and 5.0 mg l−1 BA while the hypocotyl explants gave rise to multiple shoots only on MS with 0.5 mg l−1 BA. Isolated embryos gave rise to many shoot buds on MS with 0.2 and 0.3 mg l−1 TDZ. The shoot buds elongated and rooted either on MS medium with 0.01 mg l−1 BA or on half strength MS medium lacking growth regulators, which depended upon the growth regulator used in the shoot bud induction medium. Except for the embryo-derived plantlets, all other plantlets could be acclimatized with 100% success.

Micropropagation of Pistachio from mature trees

Abstract: Multiple shoots were induced from nodal segments of mature trees of Pistacia vera L. on Murashige and Skoog (MS) medium supplemented with benzylaminopurine (BA). Maximum shoot production was obtained from shoot tips taken from in vitro proliferated shoots when cultured on solidified MS medium containing 8.8 μ MB A. The multiplication rate was 20 microshoots per explant on the 30th day. Rooting of microshoots was achieved in MS medium supplemented with indole butyric acid (IBA). Rooted plantlets reassumed independent growth after a short period of acclimatisation. Stable regenerated plants were established in the greenhouse.

Morphogenic response of the alginate-encapsulated axillary buds from in vitro shoot cultures of six mulberries

Abstract: Axillary buds obtained from in vitro shoot cultures of six mulberries (Morus alba L., M. australis Poir., M. bombycis Koidz., M. cathyana Hemsl., M. latifolia Poir., and M. nigra L.) were encapsulated in calcium alginate hydrogel containing Murashige and Skoog (1962) nutrients (MS) and 4.4 μM benzyladenine (BA). Morphogenic response of encapsulated buds to various planting media such as MS medium + 4.4 μM BA, MS basal medium, soilrite mix + half-strength MS medium, garden soil + half-strength MS medium, soilrite mix + tap water and garden soil + tap water was evaluated. Encapsulated buds of M. alba, M. bombycis, M. latifolia and M. nigra exhibited shoot development in each of the six media tested whereas that of M. australis and M. cathyana responded only to the first four media. Analysis of variance revealed that the planting medium exhibited the greatest influence on shoot development. Of the six planting media evaluated, shoot development was highest in MS medium containing 4.4 μM BA and lowest in garden soil moistened with water. Of the six Morus species studied, one-step regeneration, i.e. both shoot and root formation, was recorded in M. alba, M. bombycis and M. latifolia. Rooted shoots were retrieved from encapsulated buds of these species on all planting media tested except the one that contained BA. Root development was significantly affected by the planting medium and the plant species with planting medium contributing the maximum amount (82%) of the total variation observed. Of the five planting media tested, the percentage of root development was highest in MS basal medium. Of the six Morus species studied, the best shoot and root development was observed in M. alba. Encapsulated buds of M. bombycis, M. latifolia and M. nigra stored for 90 days and those of M. alba, M. australis and M. cathyana for 60 days at 4 °C still regenerated shoots. Plants regenerated from the encapsulated buds were hardened off and transferred to soil.

Regeneration of indian ginseng plantlets from stem callus

Abstract: The development of stem callus mediated plant regeneration system for Withania somnifera is described. Maximum callus proliferation was obtained on Murashige and Skoog medium supplemented with 2.26 μM 2,4-D. Three-week-old, white, friable callus was used for shoot regeneration. The maximum shoot regeneration (6.2 ± 0.34 shoots/explant) was achieved in four weeks when callus was cultured on MS medium fortified with 4.44 μM BA and 0.57 μM IAA. Regenerated shoots were excised and multiplied (8.4 ± 0.43 shoots/explant) on MS medium supplemented with 4.44 μM of BA. Multiple shoots were divided into single shoots and were rooted (5.1 ± 0.49 rootlets/shoot) on half strength MS medium supplemented with 9.84 μM of IBA. After a hardening phase of 3 weeks the plantlets were transferred to the field.

Effect of sugars, amino acids, and culture technique on maturation of somatic embryos of Pinus strobus on medium with two gellan gum concentrations.

Abstract: Maturation of five embryogenic lines of Pinus strobus L was tested on media with various sugars and sources of organic nitrogen, and solidified with two gellan gum concentrations (06 and 10%) Mature somatic embryo production was more abundant at 10% gellan gum than at 06% Complex combinations of amino acids had little effect on mature embryo production of most tested embryogenic lines Increasing glutamine concentration of the maturation medium from 17 to 73 g l−1 was beneficial to one embryogenic line Increasing sucrose concentration or substituting part of the sucrose with mannitol or sorbitol had variable effects on somatic embryo maturation depending on the embryogenic line A medium with 88 mM sucrose plus 175 mM sorbitol solidified with 10% gellan gum produced high numbers of somatic embryos in four out of five embryogenic lines tested

Micropropagation of Indian wild strawberry.

Abstract: An efficient method of micropropagation based on an increased percentage survival of explants and reduced phenol-induced browning in wild strawberry has been developed. Serial transfer of nodal explants was carried out at 24-, 48- and 96-h intervals. Nodal segments cultured on Murashige and Skoog medium supplemented with 6-benzyladenine (4.0 μM) and α-naphthalene acetic acid (0.1 μM) gave the best (94.4%) explant establishment and shoot number (22.3) per explant. Of the cytokinins tested, 6-benzyladenine was found more effective than kinetin and N6-(γ,γ dimethylallyamino) purine. Excised shoots rooted on half-strength agar-gelled medium with 1.0 μM α-naphthalene acetic acid. Rooted shoots with fully expanded leaves acclimatized successfully and about 70% of plantlets survived ex vitro.

Number of air exchanges, sucrose concentration, photosynthetic photon flux, and differences in photoperiod and dark period temperatures affect growth of Rehmannia glutinosa plantlets in vitro.

Abstract: Rehmannia glutinosa plantlets were cultured for 4 weeks under different culture conditions to determine the optimum environment for in vitro growth and ex vitro survival. Plantlet growth increased with an increasing number of air exchanges of the culture vessel, exhibiting greatest shoot weight, total fresh weight, leaf area, and chlorophyll content at 4.4 h−1 of air exchanges. High sucrose concentration (30 g l−1) increased root weight but reduced shoot growth. Net photosynthetic rates of the plantlets were greatest when sucrose was not added to the medium. On the other hand, ex vitro survival of the plantlets was not influenced by sucrose concentration. In the experiment on difference in photoperiod and dark period temperatures (DIF) and photosynthetic photon flux (PPF), plantlet growth increased as DIF and PPF levels increased. Particularly, increasing PPF level had a more distinctive effect on plantlet growth than increasing DIF level. The interaction of DIF × PPF was also significant, showing the greatest plantlet growth in positive DIF (+8 DIF) and a high PPF (210 μmol m−2 s−1). In conclusion, the results of this experiment suggest that increased number of air exchanges of the culture vessel, decreased sucrose concentration, and positive DIF in combination with high PPF level enhanced growth and acclimatization of Rehmannia glutinosa plantlets.

Influence of nitrogen and phosphorus on induction embryogenic callus of sorghum

Abstract: Fragments of young panicles and immature embryos of different cultivars of grain sorghum were cultured on modified MS and N6 media supplemented with L-asparagine (6.7 mM), L-proline (17.4 mM) and different concentrations of NO 3 - , NH 4 + and PO 4 3- . The panicle-derived cultures were used in experiments with different nitrogen sources; the influence of PO 4 3- level was studied in embryo-derived and panicle-derived cultures. An increase of the NO 3 - and NH 4 + levels in the media with amino acids significantly increased induction and growth of embryogenic callus (EC) and its regeneration ability. A new M2 medium, which contained 62.5 mM NH 4 + and 72.4 mM NO 3 - , exceeded other media which were previously effective for obtaining EC of sorghum. The level of NO 3 - and NO 3 - /NH 4 + ratio in the media supplemented with L-asparagine and L-proline were established to be the critical factors of friable EC formation in sorghum. High level of NH 4 + with low level of NO 3 - resulted in formation of compact EC, while increase of NO 3 - concentration (39.9–82.4 mM) in MS or N6 media favoured proliferation of friable EC in some genotypes. Formation of compact EC in the NH 4 + -rich media was accompanied by strong pigmentation of the medium, which was never observed in cultures with friable EC. An increase of the PO 4 3- level (up to 8.8–14.2 mM) was shown to increase the frequency of somatic embryogenesis by 3–4 times, the EC mass by 1.5–2.0 times and its regeneration ability. Media with increased nitrogen or phosphorus could be used for maintenance of sorghum EC for 4–5 passages; for a more prolonged maintenance, their level in the medium should be decreased.

In vitro propagation of the endangered orchid, Geodorum densiflorum (Lam.) Schltr. through rhizome section culture

Abstract: Micropropagation of the endangered terrestrial orchid, Geodorum densiflorum (Lam.) Schltr. was achieved through rhizome section culture from in vitro seed- derived rhizomes. Rhizome sections were cultured on Murashige and Skoog (MS) and Knudson C(KC) media supplemented with various growth regulators and 0.1% activated charcoal. The rhizome sections responded on MS medium. Naphthaleneacetic acid (NAA) at 2.0 μM stimulated rhizome growth. However, benzyladenine (BA) at 5.0 μM induced multiple shoots within four weeks of culture and inhibited rhizome growth. The regenerated shoots rooted on MS only or with NAA at 1.0 μM. Well-developed plantlets were transferred to community pots and then to a greenhouse where the plants have been acclimatised.

Plant regeneration via somatic embryogenesis in cotton

Abstract: An efficient in vitro plant regeneration system characterized by rapid and continuous production of somatic embryos using leaf and stem explants of abnormal seedling as an explant have been developed in Gossypium hirsutum L. Embryogenic callus and somatic embryos have been obtained directly from the explants of cotton abnormal seedlings. Plant growth regulators influenced the induction of cotton somatic embryogenesis. The optimal medium for direct somatic embryogenesis was modified MS medium supplemented with 0.1 mg l-1 ZT and 2 g l-1 activated carbon. On this medium, an average of 28.0 and 28.1 matured somatic embryos formed from per leaf and stem explants respectively. The highest frequency of somatic embryogenesis was 100%. The somatic embryos were converted into normal plantlets when cultured on modified MS medium supplemented with 0.1 mg l-1 ZT. Upon transfer to soil, plants grew well and appeared normal. Plants could be regenerated within 60–80 days. The system of cotton somatic embryogenesis and plant regeneration described here will facilitate the application of plant tissue culture and genetic engineering on cotton genetic improvement.

Thidiazuron-induced de novo shoot organogenesis on seedlings, etiolated hypocotyls and stem segments of Huang-qin

Abstract: Development of an efficient in vitro propagation system for Huang-qin (Scutellaria baicalensis), a traditional Chinese medicinal plant used in the treatment of a wide range of human ailments, is described. Thidiazuron [TDZ: N-phenyl-N′- (1,2,3-thidiazol-5-ylurea)] effectively induced regeneration on cultured intact seedlings, etiolated hypocotyl explants and sterile stem segments of Huang-qin. Histological examinations of excised hypocotyl or nodal explants revealed that adventitious shoots formed through an intermediate callus. Comparison of TDZ-induced regeneration in the three tissue types indicated that isolation of explants was not essential for optimal regenerative efficiency. Significantly more regenerants formed along hypocotyls of intact seedlings (20 shoots/explant) than were observed on excised hypocotyls (9.7 shoots/explant) indicating that endogenous metabolites produced in adjacent tissues provided resources for the shoot initiation. More than 95% of de novo regenerants formed roots and then intact plantlets under either sterile culture or greenhouse conditions. Regeneration protocols developed in this study may provide the basis for improvement of this crop through the identification of medicinally active constituents and eventual development optimized pharmaceutical products.

Recovery and regeneration of embryogenic cultures from female flowers of False Horn Plantain.

Abstract: Somatic embryogenesis from immature male flowers in Musa is only suitable for genotypes with a male bud. Six friable embryogenic cultures were obtained from 28 cultured buds of female flowers of the AAB False Horn Plantains, ‘Currare’ and ‘Currare Enano’. Embryogenic suspensions were established from these embryogenic cultures. Somatic embryogenesis was demonstrated histologicaly. Regeneration of plants was obtained either from somatic embryos directly isolated from embryogenic cultures or from suspensions after plating on a semi-solid medium. This study demonstrates that somatic embryogenesis from immature flowers is suitable for genotypes of Musa with or without male buds.

Different media requirements for micropropagation of apricot cultivars

Abstract: Factors affecting in vitro propagation of several apricot cultivars were studied. The effect of nutrient media and BA concentration were strongly genotype dependent. Generally, best results were achieved with Quoirin and Lepoivre (1977) and a modification of WPM macronutrients (Lloyd and McCown, 1981). Optimum BA concentration was different for each cultivar but best results were obtained between 1.78 and 3.11 μM. Apricot shoots rooted well with different concentrations of IBA but most shoots showed symptoms of apical necrosis that could be overcome by dipping the shoot tips in solutions of 22.2 or 44.4 μM of BA prior to transfer to rooting medium.

In vitro androgenesis of triticale in isolated microspore culture

Abstract: Culture conditions for triticale (X Triticosecale Wittmack) androgenesis were studied using microspore culture Sporophytic development of isolated triticale microspores in culture is described in five winter hexaploid triticale genotypes Microspores were isolated using a microblendor, and embryogenesis was induced in modified 190-2 medium both in the presence and absence of growth regulators The highest induction of microspore embryogenesis was obtained in a growth regulator-free medium Adventitious embryogenesis was observed during in vitro development of triticale microspores Albino and green plantlets were regenerated from embryo-like structures More than 50% of regenerants were albino In total, 126 green plantlets were produced, transplanted and established in soil Cytological evidence revealed that 90% of the transplanted regenerants were haploid

Plant regeneration from callus culture of a Paphiopedilum hybrid

Abstract: Totipotent calli of a Paphiopedilum hybrid (Paphiopedilum callosum ‘Oakhi’ × Paph. lawrenceanum ‘Tradition’) were induced from seed-derived protocorms on a 1/2 strength Murashige–Skoog medium plus 1–10 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.1–1 mg l−1 1-phenyl-3-(1.2.3-thiadiazol-5-yl)urea (TDZ). These calli grew well when subcultured on the same medium, but proliferated more on 1/2 MS medium plus 5 mg l−1 2,4-D and 1 mg l−1 TDZ. Calli developed further along a route of production of protocorm-like bodies and eventually formed plantlets that could be transplanted to pots and grew well.

In vitro storage of Eucalyptus grandis germplasm under minimal growth conditions.

Abstract: Slow growth-storage, for up to 10 months, has been achieved for Eucalyptus grandis shoot cultures by either the addition of 10 mg l−1 abscisic acid to the growth medium or by the halving of nutrient supply (half MS) and removal of exogenous plant growth regulators. Reduction of light intensity or the addition of mannitol to the media were less effective in reducing growth rate. Isolated in vitro axillary buds encapsulated in calcium alginate and stored under low temperature and low light intensities survived for up to 3 months without loss in viability. Storage of such encapsulated fresh axillary buds at higher temperature resulted in a loss in viability. These methods have immediate applications to forestry breeding and clonal programs.

The effect of gamma irradiation on potato microtuber production in vitro

Abstract: The effects of low doses of gamma irradiation and potato (Solanum tuberosum L) cultivar on the production of microtubers in vitro were investigated Nodal segments from virus free explants of three potato cultivars (cv) were placed on tuberization inducing medium and irradiated with 4 doses of gamma radiation (25, 5, 10, 15 Gy) Cv Diamant produced the highest number of microtubers followed by Draga and Spunta Irradiation of the explants with 25 Gy of gamma radiation led to a significant increase in the number of microtubers (38% increase over the control) Average weight of microtubers was not significantly influenced by low doses of gamma irradiation Draga microtubers were the largest followed by Diamant and Spunta Microtubers resembled mature tubers in shape (Spunta was oval and Draga and Diamant were spherical) Size of microtubers was crucial for sprouting in vivo It is suggested that only microtubers larger than 5 mm in diameter (250 mg) be used to produce minitubers in vivo Since 25 Gy is a low irradiation dose, it can be used to enhance tuberization in vitro without fear of genetic changes in the used cultivars

Plant regeneration via embryo and shoot bud formation from flower-stalk explants of Oncidium Sweet Sugar

Abstract: Segments taken from flower-stalk internodes of Oncidium Sweet Sugar formed somatic embryos and shoot buds directly from wound surfaces or via nodular masses proliferation within 1.5 months, when cultured on a Gelrite-gelled 1/2-MS basal medium supplemented with thidiazuron (0.1–3 mg l−1) in darkness. In light, when subcultured, these nodular masses proliferated into green compact callus, and produced somatic embryos, shoot buds and/or yellowish abnormal structures spontaneously. Supplementing 0.1–1 mg l−1 NAA enhanced embryo formation, but retarded proliferation of shoot buds and yellowish abnormal structures. Somatic embryos that directly formed from wound surfaces of flower stalk explants usually developed into abnormal structures, but the callus-derived embryos could germinate into PLBs and eventually developed to normal plantlets on a hormone-free basal medium for 3–4 weeks. Both the embryo-and shoot bud-derived regenerants developed into healthly plantlets when potted in sphagnum moss and acclimatized in the greenhouse.

Micropropagation of Pothomorphe umbellata via direct organogenesis from leaf explants

Abstract: The establishment of a micropropagation protocol for Pothomorphe umbellata was carried out using leaf segments cultured on 1/4 strength Murashige and Skoog medium supplemented with 0.5 mg l-1 6-benzyladenine, 0.1 mg l-1 gibberelic acid added with 10 g l-1 sucrose. Rooting was achieved using MS medium devoid of growth regulators. An anatomical study confirmed shoot regeneration via direct organogenesis.

Cryopreservation of in vitro -grown shoot tips of grapevine by encapsulation-dehydration

Abstract: In vitro-grown shoot tips of the LN33 hybrid (Vitis L.) and cv. Superior (Vitis vinifera L.) were successfully cryopreserved by encapsulation-dehydration. Encapsulated shoot tips were precultured stepwise on half-strength MS medium supplemented with increasing sucrose concentrations of 0.25, 0.5, 0.75 and 1.0 M for 4 days, with one day for each step. Following preculture, encapsulated shoot tips were dehydrated prior to direct immersion in liquid nitrogen for 1 h. After thawing, cryopreserved shoot tips were post-cultured on a post-culture medium for survival. An optimal survival of cryopreserved shoot tips was achieved when encapsulated shoot tips were dehydrated to 15.6 and 17.6% water content for the LN33 hybrid and cv. Superior, respectively. Comparison between the effects of dehydration with silica gel and by air drying on cryopreserved shoot tips, showed that survival was dependent on water content, not on dehydration method. The thawing method markedly affected survival of cryopreserved shoot tips, and thawing at 40 °C for 3 min was found best. No callus formation and fastest shoot elongation were obtained when cryopreserved shoot tips were post-cultured on the post-culture medium composed of half-strength MS supplemented with 1 mg l−1 BA and 0.1 mg l−1 NAA. With these optimized parameters, 60 and 40% survival of cryopreserved shoot tips were obtained for the LN33 hybrid and cv. Superior, respectively.