Mgl-1 Naphthaleneacetic Acid Research Articles

Tissue-Specific Natural Synthesis of Galanthaminein Zephyranthes Species and Its Accumulation in Different In Vitro-Grown Organs Following Methyl Jasmonate Treatment.

Galanthamine is an immensely valuable alkaloid exhibiting anti-cancer and antiviral activity. The cultivation of plant tissues in in vitro conditions is a good source for the synthesis and enrichment of secondary metabolites of commercial interest. In this study, the Amaryllidaceae alkaloid galanthamine was quantified in three Zephyranthes species, such as Zephyranthes candida, Zephyranthes grandiflora, and Zephyranthes citrina, and the impact of the methyl jasmonate (MJ) signaling molecule on galanthamine accumulation was monitored in in vitro-derived plant tissues. This is the first ever study of the MJ-regulated accumulation of galanthamine in in vitro-grown Zephyranthes tissues. Shoot regeneration was obtained in all three Zephyranthes species on Murashige and Skoog (MS) medium containing 2.0 mgL-1 benzylaminopurine (BAP) + 0.5 mgL-1 naphthalene acetic acid (NAA). The regenerated shoots were rooted on a medium containing 2.0 mgL-1 indole butyric acid (IBA). A GC-MS study of Zephyranthes extracts revealed the presence of 34 phyto-compounds of varied levels with therapeutic activities against diseases. The galanthamine content was quantified in plant parts of the three Zephyranthes species using high-performance thin layer chromatography (HPTLC); the maximum was found in Z. candida bulb (2.41 µg g-1 dry wt.), followed by Z. grandiflora (2.13 µg g-1 dry wt.), and then Z. citrina (2.02 µg g-1 dry wt.). The galanthamine content showed bulb > leaf > root source order. The in vitro-generated plantlets were treated with different MJ concentrations, and the galanthamine yield was measured in bulb, leaf, and root tissues. The highest galanthamine content was recorded in bulbs of Z. candida (3.97 µg g-1 dry wt.) treated with 150 µM MJ, showing an increase of 64.73% compared to the control. This accumulation may be attributed to MJ-induced stress, highlighting the potential commercial synthesis of galanthamine in vitro.

Phytochemical Profiles and Cytotoxic Activity of Bursera fagaroides (Kunth) Engl. Leaves and Its Callus Culture.

Bursera fagaroides, popularly used in México, possesses bioactive lignans. These compounds are low in the bark, and its extraction endangers the life of the trees. The aim of the present investigation was to search for alternative sources of cytotoxic compounds in B. fagaroides prepared as leaves and in vitro callus cultures. The friable callus of B. fagaroides was established using a combination of plant growth regulators: 4 mgL-1 of 2,4-dichlorophenoxyacetic acid (2,4-D), 1 mgL-1 Naphthaleneacetic Acid (NAA) and 1 mgL-1 Zeatin. The maximum cell growth was at day 28 with a specific growth rate of μ = 0.059 days-1 and duplication time td = 11.8 days. HPLC quantification of the dichloromethane callus biomass extract showed that Scopoletin, with a concentration of 10.7 µg g-1 dry weight, was the main compound inducible as a phytoalexin by the addition of high concentrations of 2,4-D, as well as by the absence of nutrients in the culture medium. In this same extract, the compounds γ-sitosterol and stigmasterol were also identified by GC-MS analysis. Open column chromatography was used to separate and identify yatein, acetyl podophyllotoxin and 7',8'-dehydropodophyllotoxin in the leaves of the wild plant. Cytotoxic activity on four cancer cell lines was tested, with PC-3 prostate carcinoma (IC50 of 12.6 ± 4.6 µgmL-1) being the most sensitive to the wild-type plant extract and HeLa cervical carcinoma (IC50 of 72 ± 5 µgmL-1) being the most sensitive to the callus culture extract.

Indirect shoot regeneration from callus of the shoot tip explants of Gerbera jamesonii Bolus cv. "Festival"

The study was conducted in the Tissue Culture Laboratory, Fadak Agricultural Company, Basrah, Iraq. Mother plants of the “Festival” gerbera cultivar were used for micropropagation by taking the shoot tip explants. The concentration of 2 mgL-1 benzyl adenine (BA) resulted in recording the highest percentage of response to callus induction, reaching 90%, which was significantly superior to the other two treatments, 1 and 1.5mgL-1 BA. The 1 mgL-1 BA treatment was significantly superior in response to indirect shoot generation when compared with the 1.5 and 2 mgL-1 BA treatments. The 1 mgL-1 BA treatment recorded the highest percentage of response to shoot growth induced by callus, which reached 100%. The treatment of callus grown in MS medium supplied with BA concentration of 1 mgL-1 recorded the highest average number of shoots, which reached 10 shoots per 50 mg of callus. The MS medium treatment supplied with a concentration of 0.5 mgL-1 of naphthalene acetic acid (NAA) was significantly superior to the other two treatments of 1 and 1.5 mgL-1 NAA in the percentage of shoot response to root formation. The concentration of 0.5mgL-1 NAA recorded the highest response to root formation, which reached 100%. The treatment of the MS medium supplied with a concentration of 0.5 mgL-1 NAA was significantly superior to the treatments of 1 and 1.5 mgL-1 NAA in the average number of main roots formed on the shoots. This treatment recorded the highest average of main roots, amounting to 3.2 main roots shoot-1. Callus, cultivar, indirect shoot, micropropagation, proliferation, MS salts.

Micropropagation and assessment of somaclonal variation in Galanthus transcaucasicus in vitro plantlets

Abstract In vitro culture of twin-scaling explants of Galanthus transcaucasicus with different concentrations of plant growth regulators (PGRs) including 0.5, 1, 2, 3, 4, 6, 8, and 10 mg L-1 naphthaleneacetic acid (NAA) and 0.5, 1, 2, 3, and 4 mg L-1 benzyladenine (BA) was studied. After 18 weeks, the number of regenerated bulblets and intensity of callus was measured. Subsequently, bulblets were transferred to a medium with 0.5, 1, 2, 3, and 4 mg L-1 NAA and 0.5, 1, 2, 3, and 4 mg L-1 BA and, after 15 weeks, the bulblets length and diameter were measured. The highest intensity of callus was obtained on 4 mg L-1 NAA or 8 mg L-1 NAA with 1 mg L-1 BA. The highest number of regenerated bulblets was detected with 6 mg L-1 NAA and 2 mg L-1 BA. The highest diameter of bulblets occurred on four mgL-1 NAA (9.4 mm), while the lowest was observed on 0.5 mg L-1 BA (1.83 mm). The analysis of genetic variation using ISSR revealed that there was no somaclonal variation among the regenerated plants from BA and low level of NAA, but there was a significant somaclonal variation at high concentrations of NAA.

Effect of Combined Growth Regulators on in vitro Multiplication of Recalcitrant Potato Varieties

The potato varieties studied in this paper were created at the National Institute of Research and Development for Potato and Sugar Beet Braşov. They have a high biological production capacity and are attractive and very appreciated by farmers, potato producers, consumers and processors, but manifest recalcitrance to the in vitro culture techniques. Thus we tried to find an optimal culture medium variant for these varieties, in order to obtain healty potato seed material in a short time. The study compared the effects of five different culture media using MS medium containing various concentrations of gibberelic acid (GA3) in combination with α-naphthalene acetic acid (NAA) in micropropagation of two recalcitrant potato varieties, Marvis and Brasovia. The longest shoots, maximum number of nodes and leaves, the longest roots and the best rooting efficiency were recorded on MS medium containing 2 mgL-1 GA3 and 1 mgL-1 NAA, for both varieties. The use of a larger quantity of GA3 negatively influenced the potato shoots and roots growth. The culture media using MS medium containing 4 mgL-1 GA3 and 1 mgL-1 NAA had an inhibitory effect on all the studied plantlet characteristics. The results showed that a certain combination of growth regulators (NAA and GA3) improved the micropropagation capacity of the two recalcitrant potato cultivars studied and resulted in the maximum improvement in the parameters.

Shoot Generation and Callus Induction of Dioscorea hispida Dennst by Different Plant Growth Hormones and Basal Media

Dioscorea hispida Dennst produces tuber which possess valuable medicinal properties but unsustainable harvesting has led to its reduction. The plant propagates slowly because of its low tuber sprouting rate. In average, Dioscorea hispida Dennst tubers took approximately 60 d to break dormancy and sprout. Hence, callus culture is proposed as a possible efficient type of culture for manipulation of this species. In the present study, calli were induced from stem segments to evaluate callus culture potential of Dioscorea hispida Dennst. Results indicate that the combination of 1 mgL-1 naphthaleneacetic acid (NAA), 1 mgL-1 6- benzylaminopurine (BAP) and 0.5 mgL-1 2,4-dichlorophenoxyacetic acid (2, 4-D) in Gamborg (B5) medium improved callus multiplication and differentiation in the stem culture as opposed to those in Murashige and Skoog (MS) medium. The findings from the present study provide the basis of callus culture protocol for stem explant of Dioscorea hispida Dennst with B5 being the more effective basal medium.

In vitro organogenesis and growth of Ocimum basilicum ‘Genovese’ (basil) cultivated with growth regulators

Genovese basil is a medicinal plant broadly used in medicine, perfumery, and cooking. In this study, the in vitro organogenesis and growth of Genovese basil seedlings are evaluated through the effect of growth regulators applied in different doses. Eight treatments were performed combining different concentrations of auxins and cytokinins, plus one control. At the end of the trial, growth characteristics of the seedlings were measured, and anatomical sections of the leaves and stems of the basil were prepared. The results demonstrated the need for cytokinins to increase the number and length of shoots and the length of roots. The treatment with 0.2 mgL-1 benzyl aminopurine (BAP) mgL-1 demonstrated the best result. The combined action of auxins and cytokinins increased fresh and dry masses of roots (0.3 mgL-1 BAP + 0.6 mgL-1naphthaleneacetic acid [NAA]). Partial changes in the leaf architecture as well as a reduction in the thickness of the palisade and lacunar parenchyma were observed, especially in treatment T8 (0.4 mgL-1 BAP+ 0.2 mgL-1NAA). In addition, all treatments with regulators presented adventitious roots in the stem, originating from inner-stem cells or vascular tissues. The formation of callus at the base of the plants and the occurrence of abnormal seedlings indicate that Genovese basil was responsive to the action of the growth regulators, although other factors regarding the medium could influence such responses. The growth regulators also function in the expression of genes linked to the stretching process (auxins) and cell proliferation (cytokinin).

Effects of carbendazim on <em>In vitro</em> micropropagation and flowering of pepper elder herbal plant

The present study reports on application of carbendazim for micropropagation and in vitro flowering of Peperomia pellucida. In vitro multiplication of shoot tips and axillary nodal explants were used in 25-100 mgL-1 carbendazim in 70% alcohol treatment for 5 min in MS (Murashige and Skoog) medium and MS hormone medium The explants were cultured on MS medium supplemented with auxins, cytokinins and additives (Casin hydrolyte and glutamine) used to proliferate the shoots. The maximum number of shoots (21.5/shoot tip) were developed on MS medium supplemented with 2.0 mgL-1 KIN (Kinetin) 0.5 mgL-1 NAA (α- Naphthalene acetic acid), 100 mgL-1 casein hydrolysate and 100 mgL-1 glutamine additives. The highest number of roots per shoot (17.6) and highest rooting frequency (94.2%) were obtained when the adventitious shoots were inoculated on MS medium with 1.5 mgL-1 IAA (Indole-3-acetic acid). The highest number of shoot development (75.4 %) was achieved on MS medium supplemented with 2.0 mgL-1 KIN 2.0 + 0.5 mgL-1 ABA (Abscisic acid) with 5% sucrose. It was found that MS medium devoid of 1.5 mgL-1 IAA promote the root formation and maturation of in vitro flower in P. pellucida. Acclimatized plantlets were transferred to botanical garden and the characters compared with mother plant of P. pellucida.

Effect of Growth Regulators on In-vitro Shooting of <em>Calathea ornata</em> for Commercial Cultivation

Calathea ornata is a member of the family Marantaceae, with glossy, leathery leaves in attractive dark or olive green colors. Its uniquely patterned feathered or fish-bone design of distinct white lines makes it a high demand in the foliage industry as a house plant. The aim of this study was to develop a shoot induction protocol with efficient sterilization technique, best explant type and different combination of growth regulators as a cost-effective method for commercial invitro propagation. Meristem tissue of C. ornata was successfully established with minimum contamination percentage, by following the protocol developed for surface sterilization, using stepwise rinsing with several disinfections. Different concentrations of BAP (6-Benzyl Amino Purine) and NAA (Naphthalene Acetic Acid) were tested for explant initiation and multiplication in ten replicates. The data were analyzed using ANOVA in Complete Randomized Design. The highest number of shoots was induced on MS basal media supplemented with 3.0 mgL-1 BAP and 3.5 mgL-1 NAA. Subsequently, initiated shoots were sub-cultured for shoot multiplication and the highest number of shoots and shoot length were observed in MS media in combination with BAP 3.0 mgL-1 with NAA 3.5 mgL-1 . Above stated effective sterilization and shoot multiplication protocols could be used in commercial in-vitro propagation of Calathea ornata.

In vitro plant regeneration in Capsicum chinense Jacq. (Naga Chili)

Article history: Received on: 07/01/2015 Revised on: 24/01/2015 Accepted on: 18/02/2015 Available online: 27/02/2015 An in vitro plantlet regeneration protocol was developed for Capsicum chinense Jacq. Naga Chili, one of the world’s hottest chili cultivars and an important horticultural crop of Northeast India. In vitro propagation plays a major role in conservation of genetically pure plants, crop improvement and production of disease free planting materials. The effect of different compositions of plant growth regulators on multiple shoot development and callus induction was investigated. Multiple shoot was induced by culturing explants in MS medium supplemented with Benzyl adenine (BA) in combination with Indole-3-acetic acid (IAA). Maximum numbers of shoot buds were induced in MS medium containing 5 mgl BA and 0.5 mgl IAA. Successful induction of callus from stem segments of in vitro raised plants were achieved in MS medium in combination with 3 mglBenzyl adenine (BA) and 1 mgl 1-Naphthaleneacetic acid (NAA).Shoot elongation and rooting were achieved in MS basal medium. This is the first successful report of plant regeneration from calluses in Capsicum chinense Jacq. Naga Chili. This protocol can be used as a cost effective method for the production of disease free planting materials and for genetic improvement and conservation of the crop.

English

Optimization of tissue culture conditions for Sorghum bicolor L. through somatic embryogenesis from immature embryos is important for the genetic manipulation and improvement of this agronomically valuable crop. In an attempt to develop a successfully reproducible in vitro regeneration protocol for a group of diverse sorghum genotypes, 10 sorghum lines including locally adapted and commercially important elite genotypes were assessed for their regeneration potential on different culture media–containing adequate growth regulators combinations. The maximum response of embryogenic callus induction was obtained from explants cultured on Murashige and Skoog (MS) medium supplemented with 1.5 mgL-1 of 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.7 mgL-1 L-proline. The addition of kinetin to the MS-based culture media had a negative effect on the formation of embryogenic calli. The results reveal that embryogenic callus formation and regeneration were highly genotype dependent. The line LG3 revealed the highest mean number of embryogenic callus (47.5 ± 6.0%) across the media tested. On the other hand, SPP462 was the least responsive (13.4 ± 3.3%) to embryogenic callus induction. The regeneration percentage of the different genotypes ranged from zero to 22.1%. The lines LG3, LG4, Dorado, SPGM94021 and SPMD94001 succeeded to form shoots on the three tested regeneration media. Nevertheless, the genotypes LG8 and TX2794 produced shoots on only two out of the three media. Three lines failed to regenerate on any of the tested media. Adding 0.5 mgL-1 naphthalene acetic acid and 0.5 mgL-1 of indole-3-butyric acid (IBA) did not enhance the root induction. Regenerated shoots developed into normal mature plants. Regeneration of sorghum genotypes could be improved through the use of different auxins and cytokinins in callus induction and shoot formation media. The auxin, 2,4-D was critical for the induction of embryogenic calli. However, the addition of the cytokinin (kinetin) adversely affected the formation of embryogenic callus. On the other hand, the shoot induction was more influenced by the addition of indole-3-acetic acid (IAA), 6-benzylaminopurine (BA) and thidiazuron (TDZ).   Key words: Sorghum, immature embryos, callus induction, regeneration, auxin, cytokinin.

English

The regeneration capacity between the shoot tip and petiole explants that excised from two date palm (Phoenix dactylifera L.) cutivar namely Unknown and Ferhi was compared. It was noted that the shoot tip explants started to swill after several subculture when placed on Murashige and Skoog (MS) medium supplemented with 100 mg l-1 2, 4-D, 3 mg l-16-Benzyladenine (BA) and 3 g l-1 activated charcoal while embryogenic calli was induced by culturing the petiole explants on MS medium supplemented with 1 mgl-1 2, 4-D. The data indicate that callus induction efficiency decreased with increasing 2, 4-D in the culture media. The embryonic calli were transferred into shoot inducing medium containing 1 mgl-1 BA and 1 mgl-1naphthaleneacetic acid (NAA). The developed protocol for plant regeneration using petiole explant is repeatable and takes less time (four months) compared with the shoot tips as explants which take much time (3 years). Genetic similarity between the mother plants of the Unknown and Ferhi cultivars and several plants regenerated in vitro from both cultivars were examined by random amplification polymorphic DNA (RAPD) analysis using 10 random primers. Each primer generated a unique set of amplification products ranging in size from 200-2600 bp. The data indicate that the regenerated plants from the Unknown and Ferhi cultivars showed 36.2 and 37.8 % polymorphism and sharing 63.8 and 62.2% of similarities, respectively with their mother plants. The level of genetic similarity between regenerated plants and their mother plants as revealed by RAPD analysis indicate that this regeneration protocol is promising and can be used to produce transgenic date palm plants expressing economically important genes.   Key words: Date palm, somatic embryogenesis, genetic stability, RAPD anaysis.

Mass propagation of Solanum surattense Bum. using direct adventitious shoot organogenesis from internode

An efficient and reproducible procedure was established for direct shoot regeneration of Solanum surattense Bum. using internodal explants. The shoot regeneration efficiency on Murashige and Skoog (MS) medium supplemented with 6-benzylaminopurine (BAP) was superior in compared to 6-furfurylaminopurine (Kn). The highest mean number of shoots per explant was recorded on MS medium containing 0.5 mgl-1 BAP. BAP alone was more effective for shoot regeneration than combination of BAP and -naphthaleneacetic acid (NAA). The number of shoot per explant was highest in the 4th subculture and then it was remained stable up to 6th subculture. The shoot number drastically reduced from 7th subculture when explants were repeated subculturing up to 8th subculture. Hundred percent adventitious shoots were rooted successively on half strength MS medium fortified with 0.05 mgl-1 NAA. At about 90% of the in vitro-propagated plantlets survived when they were transferred to ex vitro conditions for acclimatization.

Optimizing concentrations of growth regulators for in-vitro ginger propagation

Optimizing concentrations of growth regulators forin-vitroginger propagationThe study evaluates the performance of ginger in media containing different concentrations of growth regulators. Twenty-eight different treatment combinations of benzylaminopurine (BAP) and naphthalene acetic acid (NAA) incorporated into Murashige and Skoog (MS) medium were evaluated for optimal media composition for ginger micropropagation. The combination of 0.05 mgl-1NAA and 4.0 mgl-1BAP gave the highest shoot regeneration rate of 4.25. However, this did not differ significantly (p>0.05) from the result (3.38) from 0.05 mgl-1NAA and 1.0 mgl-1BAP. Considering the performance of the shoot tip explants in media and the need to lower the cost of micropropagation, the latter combination (0.05 mgl-1NAA and 1.0 mgl-1BAP) with 80 percent explant survival, gave an appropriate concentration of growth regulators in media composition for ginger propagation. This combination also supported root development, and perhaps would eliminate the stage ofin vitrorooting.

Somatic embryogenesis and plant regeneration in purple food yam (Dioscorea alata L.)

A study was conducted to establish a reliable procedure for somatic embryogenesis and plant regeneration from callus cultures of purple food yam (Dioscorea alata L.). The procedure involved three steps; (1) culture of nodal stem segments from greenhousegrown plants to generate in vitro plantlets; (2) induction of callus from the leaf, petiole and nodal stem tissues; and (3) initiation of somatic embryo from callus. Results showed that the agar-solidified Murashige and Skoog (MS) medium containing 30 gl-1 sugar, 0.1 gl-1 α-cysteine , 10 mgl-1 calcium pantothenic acid, 2.0 mgl-1 asparagine, 2.0 mgl-1 arginine, 80.0 mgl-1 adenine sulfate (AdSO4) and 0.1 mgl-1 naphthalene acetic acid (NAA) effectively broke dormancy of lateral buds of nodal stem cultures from both ‘VU-2’ and ‘Kinampay‘ varieties. Production of multiple adventitious shoots occurred after transfer of in vitro nodal pieces to the same medium added with 1.0 mgl-1 benzylamino purine (BAP) or, MSA medium. Callus was effectively induced from the vegetative tissues in MS medium added with 1.0 mgl-1 2,4-Dichlorophenoxy acetic acid (2,4-D) or, with picloram. Among the three types of explants, the nodal stem was the most suitable which produced purplish nodular embryogenic callus. A higher percentage of nodal stem-derived calli produced globular embryos in MS medium containing 1.0 mgl-1 2,4-D and 0.5 mgl-1 BAP, or in 1.0 mgl-1 picloram and 0.5 mgl-1 BAP than, in the plant growth regulator-free medium (control). The maturation of embryos was facilitated by one-month culture in MS medium containing 0.1 mgl-1 ABA and 100 mgl-1 glutamine. This step improved the germination of somatic embryos in one-half strength PGR-free MS medium containing 100 mgl-1 glutamine (regeneration medium). All somatic embryoderived plantlets were morphologically normal and established well in soil.

In vitro clonal propagation of dioecious Carica papaya

A procedure for in vitro propagation of dioecious papaya clones is described. A high rate of success in culture estbalishment was obtained when axillary buds were taken from lateral shoots of hedged rooted cuttings grown in a greenhouse. Seasonal endophytic contamination was suppressed by shaking propagules for 24 h in 300 mgl-1 rifampicin or by incorporating it at 50 mgl-1 into the medium. Murashige & Skoog (MS) basal medium supplemented with 0.5 mgl-1 6-benzyladenine and 0.1 mgl-1 naphthaleneacetic acid was used for establishment and proliferation. The addition of 160 mgl-1 adenine sulfate improved multiplication and shoot growth. An elongation stage on MS medium supplemented with 1.0 mgl-1 kinetin and 0.05 mgl-1 naphthaleneacetic acid was necessary before rooting. Rooting was obtained at a high rate on half-strength macroelements of MS medium supplemented with 1.0 mgl-1 indole-3-butyric acid. Commercial plots of papaya plants obtained through this procedure already exist.

Shoot regeneration of hybrid seed geranium (Pelargonium x hortorum) and regal geranium (Pelargonium x domesticum) from primary callus cultures

Procedures have been developed that increase the rate of shoot regeneration of hybrid seed geranium from month-old primary callus cultures. Hybrid geranium callus tissue covered with green nodular structures was initiated by placing shoot tip explants on solidified Murashige & Skoog medium (MS) supplemented with 2.0 mgl-1 zeatin and 1.9 mgl-1 indoleacetic acid. Hybrids Red Orbit, White Orbit and Scarlet Orbit were shown to produce 5–50 shoot primordia per explant when callus was initiated on this medium. Regal geranium callus was initiated by placing leaf explants on MS medium supplemented with 2.0 mgl-1 6-benzylaminopurine and 2.0 mgl-1 naphthaleneacetic acid. Regal geranium cultivars Tiny Tot and Lavender Grand Slam were shown to produce between 2–50 shoot primordia per explant when initiated on the same medium.

Effects of growth regulator concentrations and explant size on shoot organogenesis from callus derived from zygotic embryos of sunflower (Helianthus annuus L.)

Effects of medium growth regulator composition and embryo size on shoot organogenesis of callus derived from globular- to torpedo-shaped zygotic embryos of five sunflower (Helianthus annuus L.) genotypes were examined. Forty growth regulator combinations composed of 0 to 5 mgl-1 naphthaleneacetic acid (NAA) and 0 to 1 mgl-1 6-benzylaminopurine (BA) were tested. The frequency of zygotic embryos forming shoot-regenerating callus was analysed according to categorical data modelling using a maximum-likelihood approach. Both NAA and BA must be present to induce the formation of morphogenic callus from zygotic embryos, but each growth regulator effect varied with the genotype. For four genotypes, NAA and BA effects were neither linear nor quadratic; whereas, they were linear for the fifth one. Most effective concentrations across genotypes were 0.1 mgl-1 NAA and 0.5 mgl-1 or 0.2 mgl-1 BA. However, the optimal growth regulator combination depended on the genotype and an interaction between the two growth regulators. The frequency of shoot-regenerating callus also varied with the size of the embryo explant. For all five genotypes, 0.4 to 1.2 mm long heart-shaped zygotic embryos formed morphogenic callus more frequently than smaller less-developed ones.

Plant regeneration from oca (Oxalis tuberosa M.): the effect of explant type and culture media

Shoot regeneration has been obtained from internode and petiole sections of oca on a number of culture media supplemented with 3 mgl-1 naphthaleneacetic acid and 3 mgl-1 of either benzylaminopurine or zeatin, the latter being more effective. A greater percentage of sections from the 4th, 5th and 6th internodes (numbered from the apex) produced shoots than sections from older or younger internodes. Of five locally available genotypes based on tuber colour, a weak-growing type ‘white’ showed the greatest morphogenetic potential. Out of eight nutrient media tested, a modified B5 medium containing casein hydrolysate and L-glutamate supported the most consistent shoot regeneration. Shoot regeneration was preceded by the formation of a dark red smooth-surfaced callus. This was usually followed by the formation of a short tapering root. Swellings arose at the base of the root and developed into single or multiple shoots. These shoots were excised, rooted in basal Murashige & Skoog medium and transferred to the field.

In vitro propagation of prairie gentian

Explants of shoot tips, internodal stem sections, and leaf segments of Lisianthus, Eustoma grandiflorum (Griseb.) Schinners, ‘Dwarf Purple’ were cultured in vitro on modified Murashige and Skoog (MS) media. Explants of shoot tips and internodal stem sections developed into multiple shoots, whereas, leaf segments turned chlorotic on a medium supplemented with 3 mgl-1 benzyladenine (BA) and 0.2 mgl-1 naphthalene acetic acid (NAA). Shoot proliferation was obtained on shoot tips and leaf segments with 3 mgl-1 BA, but internodal stem sections became necrotic and died on this medium. Rooting was induced in cultures with multiple shoots by subculturing explants on a half-strength MS medium supplemented with 2 mgl-1 indole-3-acetic acid (IAA). Rooted plantlets were successfully transferred to soil.