In vitro induction of pollen embryos and plantlets in Aesculus carnea Hayne through anther culture

Uninuclear microspores in red horse chestnut anther cultures formed pollen embryos and plantlents in MS agar medium supplemented with varying 2,4-D concentrations (1.0, 1.5 or 2.0 mg l^-1) and 1.0 mg l^-1 Kin. The highest number of embryogenic anthers (38%) was obtained in MS medium containing 1.0 mg l^-1 of each 2,4-D and Kin. The ability of pollen embryos to germinate was closely correlated with normal embryo morphology and was influenced by hormone content in the medium (MS+;1.0 mg l^-1 IAA+1.0 mg l^-1 GA₃+0.1 mg l^-1 Kin+400 mg l^-1 glutamine). Pollen embryos and plantlets had the haploid chromosome number (x=n=40). Cytological examinations demonstrated pollen dimorphism of this Aesculus species.Abbreviations AC activated charcoal - 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid - Kin 6-furfurylaminopurine - GA₃ gibberellic acid - MS Murashige and Skoog     

Changes of 6-benzylaminopurine and 2,4-dichlorophenoxyacetic acid concentrations in plant tissue culture media in the presence of activated charcoal

Somatic embryos and embryogenic callus were initiated from immature zygotic embryos of ginseng (Panax ginseng C.A. Meyer). These somatic embryos were multiplied by adventitious (secondary and tertiary) embryogenesis and their growth and development were dependent on growth hormones in the medium. Auxins, 2,4-d, NAA, and IAA at 1.0 mg l^-1 were effective in inducing secondary and tertiary somatic embryos, which proliferated directly from the apical or cotyledonary portions of the primary somatic embryos. Single somatic embryos or clusters or embryos developed from the explanted primary embryos. Cytokinin (Kn, BA) inhibited adventitious embryogenesis. Secondary somatic embryos developed to maturation and later regenerated into plantlets in two stage process; firstly elongation of the shoot axes on MS +1.0 mg l^-1 Kn, secondly formation of root on 1.0 mg l^-1 Kn+1.0 mg^-1 GA₃ medium.Abbreviations 2,4-d 2,4-dichlorophenoxyacetic acid - NAA naphthaleneacetic acid - IAA in-doleacetic acid - Kn kinetin - BA benzylaminopurine - PSE primary somatic embryo - SSE secondary somatic embryo - TSE tertiary somatic embryo     

Interspecific hybridization of <Emphasis Type="Italic">Prunus persica</Emphasis> with <Emphasis Type="Italic">P. armeniaca</Emphasis> and <Emphasis Type="Italic">P. salicina</Emphasis> using embryo rescue

Embryo rescue technique was used successfully to produce interspecific hybrids by crossing peach (P. persica) as a female parent with apricot (P. armeniaca) and plum (P. salicica). In those crosses that had ‘Yuhualu’ or ‘Zhonghuashoutao’ as female parents, hybrid embryos aborted from the 7th or 8th week after pollination mainly due to post-pollination incompatibility. An embryo rescue protocol was established to rescue such embryos and recover hybrid plants. Modified half-strength MS medium containing 4 mg l⁻¹ 6-BA and 0.5 mg l⁻¹ IBA produced up to 90% germination in the embryos. Modified MS medium with 1.0 mg l⁻¹ 6-BA and 1.0 mg l⁻¹ IBA gave the highest bud induction and multiplication whereas modified MS medium containing 0.5 mg l⁻¹ IAA and 0.2 mg l⁻¹ NAA gave the best rooting percentage. All the hybrids obtained using this embryo rescue technique were verified using simple sequence repeat (SSR) markers. A series of pollen treatments were carried out to partially overcome pre-pollination incompatibility, and it was found accidentally that pollen treatment with electrostatic field not only improved pollen germination but also increased the multiplication coefficient of embryo-induced shoots.     

Somatic embryo proliferation, maturation and germination in Catharanthus roseus

In the present study an efficient somatic embryogenesis method has been developed in Catharanthus roseus. Friable embryogenic callus was induced from hypocotyl of in vitro germinated seeds on Murashige and Skoog basal nutrient media supplemented with various auxins particularly 2,4-D (1.0 mg l⁻¹). However, only NAA (1.0 mg l⁻¹) produced somatic embryos in cultures. Embryo proliferation was even high on the same medium added with BAP. Cotyledonary somatic embryo germinated and converted into plantlets in BAP (0.5 mg l⁻¹) added medium following a treatment with gibberellic acid (1.0 mg l⁻¹) for maturation. Carbon sources and concentrations had a marked influence on maturation process. Plantlet conversion was better achieved when embryos were matured on 3% fructose or 3–6% maltose. The result discussed in this paper indicates that somatic embryos were produced in numbers and converted plantlets can be used as raw material, genetic modification to embryo precursor cell may improve alkaloid yield further.     

Regeneration of Kosteletzkya virginica (L.) Presl. (Seashore Mallow) from callus cultures

Organogenic callus cultures of seashore mallow, Kosteletzkya virginica (L.) Presl., originated from excised mature embryos or stem sections of aseptically germinated plants initially cultured on Murashige & Skoog minimal organics medium containing 30000 mg l^-1 glucose, 2.0 mg l^-1 indoleacetic acid and 1.0 mg l^-1 kinetin. Plants were regenerated via shoots and roots from callus cultures following transfer through a series of media with different cytokinin/auxin ratios and changes in carbohydrate source. Meristematic regions, shoot and root primordia were observed during histological examination of the tissues. Somatic embryos were not found.     

Plant regeneration through somatic embryogenesis from mature leaf explants of Eryngium foetidum,a condiment

Eryngium foetidum L. is an important plant cultivated as a leafy vegetable and for its essential oil, which are of high economic value in international trade market. Plants were regenerated through somatic embryogenesis from mature leaf explants of field grown plants. Leaf explants produced dark brown, compact callus on Linsmaier and Skoog (LS) medium with the combination of 1.0 mg l^-1 2,4-dichlorophenoxy acetic acid (2,4-D) and 1.0 mg l^-1 benzylaminopurine (BAP). Somatic embryos were induced from embryo-forming callus cultures on Murashige and Skoog (MS) medium supplemented with 0.1 mg l^-1 2,4-D, 2.0 mg l^-1 BAP and 1.0 mg l^-1 gibberellic acid (GA₃). Subsequently, conversion of these somatic embryos into plantlets occurred on MS medium supplemented with 1.0 mg l^-1 GA₃ and/or 0.1 mg l^-1 BAP. The regenerated shoots were rooted and elongated on MS medium supplemented with 0.1 mg l^-1 IAA and 1.0 mg l^-1 GA₃. These plantlets were hardened and transferred to the soil. This revised version was published online in June 2006 with corrections to the Cover Date.     

Callus induction and high-efficiency plant regeneration via somatic embryogenesis in <Emphasis Type="Italic">Papaver nudicaule</Emphasis> L., an ornamental medicinal plant

We describe culture conditions for a high-efficiency in vitro regeneration system of Papaver nudicaule through somatic embryogenesis and secondary somatic embryogenesis. The embryogenic callus induction rate was highest when petiole explants were cultured on Murashige and Skoog (MS) medium containing 1.0 mg l⁻¹ α-naphthaleneacetic acid (NAA) and 0.1 mg l⁻¹ 6-benzyladenine (BA) (36.7%). When transferred to plant growth regulator (PGR)-free medium, 430 somatic embryos formed asynchronously from 90 mg of embryogenic callus in each 100-ml flask. Early-stage somatic embryos were transferred to MS medium containing 1.0 mg l⁻¹ BA and 1.0 mg l⁻¹ NAA to germinate at high frequency (97.6%). One-third-strength MS medium with 1.0% sucrose and 1.0 mg l⁻¹ GA₃ had the highest frequency of plantlet conversion from somatic embryos (91.2%). Over 90% of regenerated plantlets were successfully acclimated in the greenhouse. Secondary somatic embryos were frequently induced directly when the excised hypocotyls of the primary somatic embryos were cultured on MS medium without PGRs. Sucrose concentration significantly affected the induction of secondary embryos. The highest induction rate (89.5) and number of secondary somatic embryos per explant (9.3) were obtained by 1% sucrose. Most secondary embryos (87.2–94.3%) developed into the cotyledonary stage on induction medium. All cotyledonary secondary embryos were converted into plantlets both in liquid and on semisolid 1/3-strength MS medium with 1.0% sucrose.     

Plant regeneration through somatic embryogenesis on Holostemma ada-kodien,a rare medicinal plant

Plant regeneration through indirect somatic embryogenesis has been established on Holostemma ada-kodien Schult. Type of auxin significantly influenced somatic embryogenesis. Friable callus, developed from leaf, internode and root explants on Murashige and Skoog (MS) medium supplemented with 2,4-D (1.0 mg l^–1), was most effective for the induction of somatic embryos. Subculture of the friable callus developed on 2,4-D (1.0 mg l^–1) onto solid or liquid 1/2 MS medium with 0.1 or 0.5 mg l 2,4-D turned the callus embryogenic. Suspension cultures were superior to static cultures (solid medium) for the induction of somatic embryos. Transfer of embryogenic callus to liquid 1/2 or 1/4 MS medium with lower levels of 2,4-D (0.05–0.1 mg l^–1) induced the highest number of somatic embryos. An average of 40 embryos were obtained from 10 mg callus. Fifty per cent embryos exhibited maturation and conversion upon transfer to 1/10 MS basal solid medium. Plantlets were established in field conditions and 90 per cent survived.     

Somatic embryogenesis in sisal (Agave sisalana Perr. ex. Engelm)

A protocol has been developed for somatic embryogenesis and plant regeneration of sisal (Agave sisalana Perr. ex. Engelm). Embryogenic callus cultures were initiated from young shoots raised in vitro from the stem portion of the bulbil on medium supplemented with 1–2 mg l^-1 kinetin (KN) and 0.2–0.5 mg l^-1 -naphthaleneacetic acid plus KN or 1–1.5 mg l^-1 benzylaminopurine (BAP) or 0.25–0.5 mg l^-1 2,4-dichlorophenoxyacetic acid plus BAP or 0.5–1.0 mg l^-1 KN. Embryos at various developmental stages (globular-, heart- or torpedo-shaped) produced mature and germinating embryos on being transferred to a new medium containing 0–0.25 mg l^-1 KN. After 28 days, a maximum of 76% germinated embryos was obtained on a medium supplemented with 0.1 mg l^-1 KN. The capacity for embryogenesis remained constant in the callus upon subculturing on the same medium for more than 48 months. Histological observations showed a distinct multicellular origin for most of the somatic embryos as they developed from epidermal, sub-epidermal and inside callus cells, while a few of them originated from a superficial callus cell. Plantlets regenerated from embryos were transferred to the field where their survival rate was 100%.Abbreviations BAP Benzylaminopurine - 2,4-D 2,4-Dichlorophenoxyacetic acid - IAA Indoleacetic acid - KN Kinetin - NAA -Naphthaleneacetic acidCommunicated by W. Barz     

Strategies for overcoming genotypic limitations of in vitro regeneration and determination of genetic components of variability of plant regeneration traits in sorghum

Development of suitable strategy to overcome genotypic limitations of in vitro regeneration in sorghum would help utilize high yielding but poor tissue culture responsive genotypes in genetic manipulation programmes. A factorial experiment was conducted with two explants (immature embryos and inflorescences), eight genotypes (five Sorghum sudanense and three Sorghum bicolor genotypes), three levels of 2,4-D (1 mg l⁻¹, 3 mg l⁻¹, and 5 mg l⁻¹), and two levels of kinetin (0.0 mg l⁻¹ and 0.5 mg l⁻¹). The induced callus was transferred to the regeneration media with factorial combinations of IAA (1.0 mg l⁻¹ and 2.0 mg l⁻¹) and kinetin (0.5 mg l⁻¹ and 1.0 mg l⁻¹). S. sudanense regenerated at significantly higher frequency (38.91%) and produced shoots more intensely (2.2 shoots/callus) than S. bicolor (26.93%, 1.26 shoots/callus). Immature inflorescences regenerated at a much higher frequency (46.48%) and produced significantly more number of shoots (2.71 shoots/callus) than immature embryos (22.35%, 0.99 shoots/callus). Moreover, differences for plant regeneration between genotypes of the same species were minimal when using immature inflorescences. Increase in the 2,4-D concentration in callus induction media exhibited inhibitory effect on callus induction, growth, shoot induction and number of shoots/callus but inclusion of kinetin in callus induction media improved these responses. Use of immature inflorescence explant and inclusion of kinetin in callus induction media could overcome genotypic limitations of plant regeneration to a large extent. The extent of variability, heritability and expected genetic advance was more in plant regeneration traits than in callus induction traits. This indicated that the variability in respect of these attributes in the genotypes may be due to the additive gene action and selection of genotypes for these characters would be rewarding.     

Rapid propagation of Eleutherococcus senticosus via direct somatic embryogenesis from explants of seedlings

Explants from three different parts (cotyledon, hypocotyl or root) of one week-old seedlings of Eleutherococcus senticosus were cultured on Murashige and Skoog (MS) medium with 1.0 mg l^-1 2,4-D. Somatic embryos were formed directly from the surfaces of explants. The frequency of direct somatic embryo formation was the highest in the hypocotyl segments (75%) as compared to cotyledon (56%) or root segments (12%). When hypocotyl explants from 3 different stages of seedlings (zero, one or three week-old) were cultured on MS medium with 1.0 mg l^-1 2,4-D, the frequency of somatic embryo formation rapidly declined as the zygotic embryos germinated. However most somatic embryos (93%) from explants of zygotic embryos developed as fused state (multiple embryo), whereas somatic embryos (over 89%) from more developed seedlings developed into single state (single embryo). Single embryos germinated and regenerated into plantlets with both shoots and roots, while multiple embryos only regenerated into only multiple shoots. Plantlets that regenerated from single embryos of E. senticosus were acclimatized in a greenhouse. This revised version was published online in June 2006 with corrections to the Cover Date.     

Factors influencing efficiency of somatic embryogenesis of Gentiana kurroo (Royle) cell suspension

In this paper, we would like to show unexpected morphogenic potential of cell suspensions derived from seedling explants of Gentiana kurroo (Royle). Suspension cultures were established with the use of embryogenic callus derived from seedling explants (root, hypocotyl and cotyledons). Proembryogenic mass proliferated in liquid MS medium supplemented with 0.5 mg l⁻¹ 2,4-D and 1.0 mg l⁻¹ Kin. The highest growth coefficient was achieved for root derived cell suspensions. The microscopic analysis showed differences in aggregate structure depending on their size. To assess the embryogenic capability of the particular culture, 100 mg of cell aggregates was implanted on MS agar medium supplemented with Kin (0.0–2.0 mg l⁻¹), GA₃ (0.0–2.0 mg l⁻¹) and AS (80.0 mg l⁻¹). The highest number of somatic embryos was obtained for cotyledon-derived cell suspension on GA₃-free medium, but the best morphological quality of embryos was observed in the presence of 0.5–1.0 mg l⁻¹ Kin, 0.5 mg l⁻¹ GA₃ and 80.0 mg l⁻¹ AS. The morphogenic competence of cultures also depended on the size of the aggregate fraction and was lower when size of aggregates decreased. Flow cytometry analysis reveled luck of uniformity of regenerants derived from hypocotyl suspension and 100% of uniformity for cotyledon suspension.     

Interactions of ancymidol with sucrose and α-naphthaleneacetic acid in promoting asparagus (Asparagus officinalis L.) somatic embryogenesis

Interactions of varying ancymidol concentrations with those of α-naphthaleneacetic acid (NAA) or sucrose in embryo induction medium were related to the production and development of asparagus (Asparagus officinalis L.) somatic embryos, and to the ability of these embryos to germinate. A significant sucrose×ancymidol interaction was observed only for the production of bipolar embryos; 4% sucrose with 0.75 mg l^–1 ancymidol gave the best result, 78 g^–1 callus. The frequency of globular embryos decreased as sucrose or ancymidol concentrations increased. Sucrose concentration affected embryo germination; 3% and 4% sucrose were optimal with approximately 60% and 40% of bipolar and globular embryos germinating, respectively. Significant ancymidol×NAA interactions were observed for the production of bipolar and globular embryos and their germination. Varying ancymidol concentrations affected embryo production and germination in combination with 0.1 mg l^–1 NAA, but not with 1.0 mg l^–1 NAA. The treatment combination of 0.1 mg l^–1 NAA with 0.75 mg l^–1 ancymidol produced the most bipolar embryos, 64 g^–1 callus, and the greatest percentages of bipolar and globular embryos germinated, 63% and 42%, respectively. Received: 19 August 1996 / Revision received: 24 April 1997 / Accepted: 22 May 1997     

Biological removal of inorganic Hg(II) as gaseous elemental Hg(0) by continuous culture of a Hg-resistant Pseudomonas putida strain FB-1

A strain of broad-spectrum, mercury-resistant Pseudomonas putida FB1 was used to remove mercury as the gaseous element (Hg(0)) from a continuous axenic culture, fed with a synthetic medium containing 1 mg Hg l^-1 as HgCl₂. Mercury determinations were performed in steady-state cultures using various culture fractions [whole culture, filtered supernatant, bacterial cells (dry wt), recovery trap liquid] in order to determine the removal efficiency at different dilution rates (from 0.1 to 3.0 day^-1). The removal efficiency ranged from 99.2% to 99.8%, and the residual Hg was maintained below 5 l^-1 (the maximum allowable concentration of Hg in liquid wastes according to Italian law) at a dilution rate of 1.0 day^-1, corresponding to a Hg flux of 40 g l^-1 h^-1. Hg accumulation by cell biomass was negligible for dilution rates under 1.0 day^-1. A progressive accumulation of Hg, both in the liquid phase and in cells, occurred at a higher dilution rate (3.0 day^-1; close to washout), corresponding to a Hg concentration of 25 g g^-1 (dry wt). The estimated K_m and V_max for Hg reduction were 0.241 mg l^-1 and 9.5 mg g^-1 h^-1, respectively. In batch experiments maximum Hg removal occurred at the optimum growth temperature (28°C) of P. putida. The maximum recovery of Hg in the liquid trap was 78%.     

Somatic embryogenesis of the banana hybrid cultivar FHIA-18 (AAAB) in liquid medium and scaled-up in a bioreactor

The development of somatic embryos in liquid culture medium has a number of advantages for large-scale propagation of plants. This paper describes an improved system for the mass propagation via somatic embryogenesis of the banana hybrid cultivar FHIA-18 (AAAB). Explants from immature male flowers were used to form high frequency embryogenic tissue, this tissue was then used to establish embryogenic cell suspensions in a basic MS medium plus 1.0 mg l^–1 biotin, 100 mg l^–1 glutamine, 100 mg l^–1 malt extract (Sigma), 1.0 mg l^–1 2,4-D and 45 g l^–1 sucrose. Secondary multiplication of somatic embryos was achieved in liquid media in rotary shaker and in bioreactors. The number of embryos per litre obtained with 80.0% DO₂ and effects of pH were also studied. A high regeneration percentage of plants were obtained (89.3%) in only 1 month of culture, somatic embryos were then placed to germinate in temporary immersion systems and field testing of somaclonal variation.     

An evaluation of antibiotics for the elimination of Agrobacterium tumefaciens from walnut somatic embryos and for the effects on the proliferation of somatic embryos and regeneration of transgenic plants

Four antibiotics were evaluated for their effects on eliminating the hypervirulent Agrobacterium tumefaciens strain C58C1 ATHV Rif^R (pEHA101)/p35-gus-intron from walnut somatic embryos and on the production of secondary somatic embryos and the transformed somatic embryos. Exposure to 100–1000 mg l⁻¹ of ampicillin, carbenicillin or cefotaxime respectively for up to 60 days did not eliminate the A. tumefaciens while timentin at 500–1000 mg l⁻¹ eradicated it from somatic embryos. One-hour acidified medium treatments and the addition of 100 mg l⁻¹ kanamycin to 500 mg l⁻¹ ampicillin, carbenicillin, cefotaxime or timentin were of little help in eliminating the Agrobacterium. All four antibiotics reduced somatic embryo production, carbenicillin minimally and cefotaxime maximally, especially at higher concentrations, in comparison with antibiotic-free medium. Putative transformed embryos were selected for continued proliferation on a 100 mg l⁻¹ kanamycin-containing medium. Histochemical assessments indicated that more gus-positive somatic embryos, particularly fully gus-positive embryos, regenerated from timentin-containing medium than from other antibiotic-containing media under equivalent conditions. Transformed embryos have been grown and converted into plants and gus activity was observed in whole plants. Received: 13 July 1999 / Revision received: 2 December 1999 / Accepted: 6 December 1999     

Maturation of black spruce somatic embryos. Part I. Effect of l-glutamine on the number and germinability of somatic embryos

Different concentrations of l-glutamine and different nitrogen sources in the medium were compared during maturation of black spruce (Picea mariana (Mill.) B.S.P.) somatic embryos. l-glutamine can be used as the sole nitrogen source for the maturation of Picea mariana somatic embryos at 2 to 3 gl^-1. A significantly lower number of somatic embryos was obtained on a medium prepared with only inorganic nitrogen. Compared with a medium supplement to inorganic nitrogen resulted in a twofold increase in the number of embryos for six genotypes. The nitrogen source and concentration in the maturation medium significantly affected the germination sensus stricto of somatic embryos (radicle appearance), but not their development into plantlets; at the time of epicotyl appearance, an effect of the nitrogen source was no longer found. A comparison of the development of somatic embryos into plantlets from seven genotypes showed that the genotype had more effect in terms of epicotyl appearance and in conversion rate than the nitrogen source present in the maturation medium.Abbreviations HLM-1 half-Litvays's medium with 10 M 2,4-D and 5 M BA - i only inorganic nitrogen in the medium - i+1 gG inorganic nitrogen plus 1 g l^-1 glutamine in the medium - SMM standard maturation medium - 2.5gG only 2.5 g l^-1 glutamine in the medium     

Plant regeneration via somatic embryogenesis from protoplasts of Uganda cherry orange (Citropsis schweinfurthii)

Protoplasts isolated from embryogenic callus of Citropsis schweinfurthii (Engl.) Swing. & M. Kell were cultured in MT (Murashige and Tucker 1969) basal medium containing 5% sucrose supplemented with 0.0, 0.001, 0.01, 0.1 or 1.0 mg l^–1 BA, 0, 300, 600 or 900 mg l^–1 malt extract and 0.6 M sorbitol. The highest plating efficiency was obtained on MT basal medium containing 5% sucrose supplemented with 0.01 mg l^–1 BA and 600 mg l^–1 malt extract. MT basal medium containing 5% sucrose and supplemented with 0.01 mg l^–1 kinetin was found to be a medium suitable for the development of globular somatic embryos derived from protoplasts into heart-shaped somatic embryos with cotyledon-like structures. The highest percentage of shoot formation was obtained using 0.1 mg l^–1 GA₃. A complete protoplast to-plant system was developed for C. schweinfurthii, which could facilitate the transfer of nuclear and cytoplasmic genes from this species into cultivated Citrus through protoplast fusion.Abbreviations BA N⁶-benzyladenine - 2,4-D 2,4-dichlorophenoxyacetic acid - FDA fluorescein diacetate - GA₃ gibberellin A₃ - ME malt extract     

High-efficiency somatic embryogenesis and plant regeneration in California poppy, Eschscholzia californica Cham.

 The development of a rapid protocol for high-efficiency somatic embryogenesis and plant regeneration from seed-derived embryogenic callus cultures of California poppy (Eschscholzia californica Cham.) is reported. The optimized procedure required less than 13 weeks from the initiation of seed cultures to the recovery of plantlets and involved the sequential transfer of cultures onto solid Murashige and Skoog basal medium containing three different combinations of growth regulators. All steps were performed at 25  °C. Friable primary callus was induced from seeds of E. californica cultured on medium supplemented with 1.0 mg l⁻¹ 2,4-dichlorophenoxyacetic acid. The primary callus was transferred to medium containing 1.0 mg l⁻¹ 1-naphthaleneacetic acid and 0.5 mg l⁻¹ 6-benzylaminopurine to establish embryogenic callus and promote somatic embryogenesis. Regenerated plantlets were recovered after the conversion of somatic embryos on medium containing 0.05 mg l⁻¹ 6-benzylaminopurine and showed normal development. Embryogenic callus was induced at a frequency of 85%, an average of 45 somatic embryos were produced per callus, 90% of the somatic embryos converted, and about 70% of the plantlets were recovered in soil. The growth rate of somatic embryo-derived shoots could be increased by gibberellic acid treatment, but the resulting plantlets were hyperhydritic. Received: 14 February 1999 / Revision received: 27 April 1999 / Accepted: 14 May 1999     

Micropropagation of bromeliad <Emphasis Type="Italic">Aechmea fasciata</Emphasis> via floral organ segments and effects of acclimatization on plantlet growth

Although suckers and seedlings can be used for the propagation of bromeliads, the low number of propagules and cross-variation limit their uniformity and mass cultivation. In this study, high-efficiency shoot organogenesis and plant regeneration were achieved on callus derived from petal and ovary explants of Aechmea fasciata (Bromeliaceae). Calluses were induced on half-strength Murashige and Skoog inorganic salts (1/2MS) supplemented with 1.0–1.5 mg l⁻¹ 2,4-dichlorophenoxyacetic acid in combination with 1.0 or 0.5 mg l⁻¹ α-naphthaleneacetic acid (NAA), and shoots regenerated after transfer to 1/2MS basal medium containing the combination of 1.0 mg l⁻¹ NAA + 0.5 mg l⁻¹ 1-phenyl-3-(1,2,3-thiadiazol-5-yl) urea. Those plantlets grown under a middle light intensity (50 μmol m⁻² s⁻¹) showed a dramatic increase in survival percentage (up to 95%) and the maximum number of newly developing roots. The plantlets that were transplanted onto pots were successfully grown in the greenhouse.