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An efficient protocol is reported for in vitro plant regeneration through somatic embryogenesis in Piper aduncum, a Brazilian Amazon species with high economic potential. The species is important due to a variety of components found in its essential oil, with emphasis on dillapiole. Leaf explants from five accessions identified for high oil yield and levels of dillapiole were evaluated for their embryogenic potential. To induce embryogenic calli, the explants were cultivated in MS medium supplemented with 5 mg L−1 of 1-naphthaleneacetic acid (NAA) and 2.5 mg L−1 of N6-benzylaminopurine (BAP) for 80 d. For somatic embryogenesis, the embryogenic calli were transferred to MS medium with 10 mg L−1 of NAA and 2.5 mg L1 of BAP and incubated for 45 d. The obtained somatic embryos were germinated in MS medium without regulators by 45 d and the obtained plantlets were subjected to acclimatization. Somatic embryos and calli from this process were subjected to anatomical and histochemical analyses. Biochemical analyses (total soluble sugars, starch, total amino acids, and proteins) were also performed to identify markers for embryogenic competence acquisition. In addition, the germination of somatic embryos was evaluated in a semi-solid and liquid system (R.I.T.A.® temporary immersion bioreactors). The obtained plants were evaluated for genetic fidelity using ISSR markers. The present study indicate that the accessions did not differ in embryogenic potential, with a mean percentage of calli with somatic embryos of 82.4%. Anatomical analyses confirmed the occurrence of the embryogenic route and the histochemical analyses identified starch grains in somatic embryos at different developmental stages. The biochemical analyses showed high total soluble sugars and total amino acids in embryogenic calli, marks of the acquisition of the embryogenic competence of P. aducum. The R.I.T.A.® temporary immersion bioreactors were highly efficient in the regeneration of somatic plants, with 100% germination. The plants regenerated in the semi-solid and liquid systems showed high genetic homogeneity. The survival rate of the acclimatized plants was 100%.

Admittedly, Pisifera genotypes are less responsive to somatic embryogenesis than other genotypes, such as inter- or intra-specific oil palm hybrids. However, clonal propagation of Pisifera plants can be useful for increasing the number of male parents to cross with the Dura variety for mass producing the Tenera commercial varieties. The capacity for somatic embryogenesis (SE) of Brazilian Pisifera genitors was therefore investigated using achlorophyllous leaf explants from four field growing genotypes (A251424, A251427, A251512, A251513). A Murashige & Skoog (MS) medium supplemented with 0.5 gL−1 glutamine, 0.5 gL−1 casein, 2.5 gL−1 activated charcoal, 450 µM Picloram and 2.5 gL−1 Phytagel was used for the induction. A251424 showed the higher capacity for SE induction with 45.8% of callus formation compared to 11.3% for A251427, 7.7% for A251513 and 0.6% for A251512. The materials remained in these conditions for up to 360 days, being subcultured every 150 days before transfer for 90 days onto the multiplication medium (MM), containing 40 μM Picloram and 10 μM 2-isopentenyladenine (2iP). Callus fresh biomass increased approximately fivefold in these MM conditions. The calli were then placed onto the somatic embryo differentiation medium (DM), composed of 12.3 μM 2iP and 0.54 μM naphthalene acetic acid (NAA) until the formation of the first somatic embryo clusters. These were transferred to the somatic embryo regeneration medium (RM) totally lacking growth regulators but with 2.5 gL−1 activated charcoal. Histocytological observations indicated that cells showing the greater concentration of starch granules could be considered as embryogenic with the higher capacity for SE. To our knowledge, this is the first report on the successful use of immature leaf explants for producing SE from Pisifera genitors of Elaeis guineensis.

Butia odorata is a palm native to southern Brazil and Uruguay, not domesticated, much appreciated for its fruits and economic potential. However, the extractivism and the difficulty of propagation have led to the decline of natural populations. The objective of this work was to prove the possibility of induction of somatic embryogenesis in B. odorata. Mature zygotic embryos were induced in two media, MS and Y3, combined with auxin 2,4-D and picloram in five concentrations (2,4-D: 0, 361.99, 452.49, 542.99 and 633.48 μM/L, picloram: 0, 50, 150, 300 and 450 μM/L). The results promising during induction with the formation of embryogenic calli and somatic embryos, however the regeneration of them was not efficient, this may be due to the occurrence of somatic embryos fused during its development. The roots were formed, but the aerial part remained molten, not completing its development. Auxin picloram and Y3 medium provided the most adequate conditions for calogenesis, formation of embryogenic callus and somatic embryos, with concentrations of 150, 300 and 450 μM/L. This is the first description of somatic embryogenesis in B. odorata that will serve as the basis for future research and adjustments of the methodology proposed here.

Anatomical and histochemical studies were carried out during the somatic embryogenesis of Syagrus oleracea (Mart.) Becc. from immature inflorescences. Immature rachillas were inoculated on Murashige and Skoog medium with 4.52 μM 4-amino-3,5,6-trichloropicolinic acid (Picloram) and 2,4-diclorophenoxyacetic acid. Auxin concentrations were gradually reduced for the formation of somatic embryos, while for plantlet regeneration, embryos were inoculated on a medium without growth regulator. After 270 days, two types of embryogenic calluses were observed in explants under the effect of Picloram: nodular, with a smooth surface and those without definite shape, with an irregular surface, both presenting a meristematic zone with polysaccharide content. Callus progression to the differentiation stage allowed for the conversion of somatic embryos, some with a well-defined protoderm and procambial bundles. The histochemical analysis of the somatic embryos did not identify the presence of polysaccharide and protein reserves, which emphasizes the necessity for optimization of the maturation conditions.

This paper, in an unprecedented way, describes the ontogenesis of calli and somatic embryos of macaw palm (Acrocomia aculeata) from young leaf tissues of adult plants, aiming to elucidate the events underlying the process and consequent optimization of the technique. Leaves were inoculated in a callus induction medium, composed of Y3 salts, 2.5 g L−1 activated charcoal and 450 μM Picloram. For multiplication of the calli, they were separated from the explants and inoculated in a medium with the same composition as the previous phase. Histological analyses were performed on samples of immature leaves with and without calli at 0, 3, 15, 30, 60, 90 and 120 days in an induction medium, and on samples of the different types of calli and somatic embryos obtained during multiplication and differentiation. For this, the samples were fixed in FAA, dehydrated in an alcohol series and infiltrated in resin. Anatomical sections obtained on a microtome were stained with Toluidine Blue for structural characterization. At 60 days, analyses revealed the formation of callogenic masses in the vicinity of smaller vascular bundles. This multiplication approach allowed for the proliferation of the primary cell mass that evolved into new lineages of calli, especially the embryogenic yellowish nodular lineage, which originated somatic embryos. Additional histochemical analyses showed starch accumulation only in the adjacencies of areas undergoing intense cell division. The morpho-anatomic characterization allows the rapid identification of potential calli for the formation of somatic embryos from leaf tissues in macaw palm and promotes future investigations of the participation of vascular tissues in the events that precede somatic embryogenesis.

A somatic embryogenesis protocol was developed from the immature leaves of adult plants of the macaw palm. Leaf explants from different regions of the palm heart were used for callus initiation in a modified Y3 medium, supplemented with 2,4-D or Picloram at 450 μM. Calli were separated from the leaf explants at 6-, 9- and 12-month periods and transferred to a fresh culture medium of the same composition. They were multiplied for up to 120 days. Reduced concentrations of 2,4-D and Picloram were used to differentiate somatic embryos. They were then germinated in a medium without plant growth regulators. Morphological and anatomical analyses were conducted at different stages of the embryogenic process. The best results for callus induction were achieved by Picloram, when explants were maintained for up to 9 months on culture medium (64.9%). The farthest portions of the apical meristem were those that provided the biggest calli formation. The formation of the somatic embryos was observed from the calli multiplication phase. Reduction in concentrations of growth regulators failed to promote the formation of complete plants. Picloram at 450 μM promotes high callogenesis in leaf tissues of macaw palm, with a potential for somatic embryo formation.

The current analysis describes an improved protocol for somatic embryogenesis and plant regeneration in oil palm (Elaeis guineensis) through liquid medium, and assesses the influence of successive subcultures during induction of calluses in three Brazilian oil palm varieties. Calluses were induced in a Murashige and Skoog (MS) medium with 450 Picloram, 0.5 g L−1 glutamine, 2.5 g L−1 activated charcoal, 30 g L−1 sucrose, and solidified with 2.5 g L−1 Phytagel. In a first experiment, the effect of continued subculture of explants every 30 days to fresh culture medium was determined. During a second experiment, part of the embryogenic calluses obtained were transferred to a liquid medium under agitation, consisting of MS with 5 µM picloram or 2,4-dichlorophenoxyacetic acid (2,4-D). After 210 days, the calluses were transferred to semi-solid media for differentiating somatic embryos. It was observed that continued subculture of explants monthly was a determinant in stimulating and improving the format...

Somatic embryogenesis in palm trees is, in general, a slow and highly complex process, with a predominance of the indirect route and, consequently, a lack of knowledge about the direct route. We present new knowledge related to the morphological, histochemical and ultrastructural aspects of the transition from somatic to embryogenic cells and direct formation of somatic embryos from mature zygotic embryos of Syagrus oleracea, a palm tree. The results support the general concept that 2,4-dichlorophenoxyacetic acid plays a critical role for the formation of somatic embryos of direct and multicellular origin. Seven days in medium with auxin were enough for the identification of embryogenic cells. These cells had a set of characteristics corresponding to totipotent stem cells. At 14 days on induction medium, nodular formations were observed in the distal region of inoculated embryos, which evolved into globular somatic embryos. At 120 days on induction medium, the quality of the somatic embryos was compromised. The dynamics of the mobilization of reserve compounds was also demonstrated, with emphasis on starch and protein as energy sources required for the embryogenic process. This study shows for the first time the anatomical and ultrastructural events involved in direct somatic embryogenesis in a palm tree and incites the scientific community to return to the discussion of classical concepts related to direct somatic embryogenesis, especially regarding the characteristics and location of determined pre-embryogenic cells.

A somatic embryogenesis protocol for the acai palm (Euterpe oleracea Mart.) was developed, based on mature and immature zygotic embryos, to define morphoanatomically the process’s different stages and to analyze the homogeneity of nuclear DNA content by flow cytometry from calli, somatic embryos and regenerated plants. Auxin picloram (4-amino-3,5,6-trichloropicolinic acid) was tested to induce embryogenic calli at 225 and 450 μM concentrations, coupled to the physiological maturing stages of zygotic embryos (mature and immature). Murashige and Skoog (MS) medium with 30 g l−1 sucrose, 2.5 g l−1 Phytagel, 2.5 g l−1 activated charcoal and 0.5 g l−1 l -glutamine was employed for callus induction. Embryogenic calli with somatic embryos in initial differentiation were transferred to a culture medium with 12.3 μM of 2iP and 0.6 μM of NAA and 300 mg l−1 of activated charcoal for differentiating and maturing somatic embryos. Plant regeneration occurred in a medium with 1.0 μM BAP (N6-benzylaminopurine) and 0.5 μM GA3 (gibberellic acid). The formation of embryogenic calli in all treatments was observed in the induction medium, regardless of the stage of development of the zygotic embryo. Picloram at 450 μM concentration provided the best results in forming embryogenic calli (84.7%). In the differentiating and maturing stage, 100% of the explants that had an embryogenic callus formation resulted in somatic embryos. The largest rate of plant regeneration (58.7%) was noted in treatment with an induction medium of 450 μM of picloram and somatic embryos obtained from immature zygotic embryos. Morphoanatomical analyses evidenced that induction of somatic embryogenesis reflected stages characteristic of the indirect kind. Regenerated plants showed normal development, with growth of roots and aerial part. Calli, somatic embryos and plants, analyzed by flow cytometry, revealed no significant differences in the estimated rates of DNA content.

Several biochemical components associated with different stages of somatic embryogenesis in coffee (Coffea arabica L.) are investigated using foliar explants. Soluble sugar, starch, free amino acids and total proteins were extracted and quantified at different stages of somatic embryogenesis, such as foliar segments (initial explants), primary calluses, embryogenic calluses, globular embryos, torpedoes, cotyledonary embryos and mature fruit zygotic embryos. Total soluble sugar levels increased sixfold at the initial stages of somatic embryogenesis induction. During this period, total soluble sugar in the cultures contained approximately 99.3% glucose and fructose. At 67.4 μg/mg MS, no significant changes were observed in total sugar content during the embryo’s somatic maturation and regeneration. During this stage, total soluble sugar was composed of 60% sucrose. After primary callus formation, starch contents increased gradually until the culture’s conclusion. Total free amino acids, particularly arginine, lysine, methionine, asparagine, glutamine and histidine, revealed a higher synthesis until the formation of the primary callus, after which they remain statistically constant up to the end of the process. During the induction of calluses, a gradual increase of total proteins occurred, which, in the differentiating and maturing of somatic embryos, did not differ statistically till the formation of a cotyledonary embryo, when rates decreased 21.8%.

In vitro conservation techniques can be utilized for germplasm maintenance. However, few reports on the in vitro conservation of sugarcane species are present in the literature. The objective of this study was to subject sugarcane plants to in vitro under minimal growth conditions and to evaluate the survival, regeneration, and the monitoring of nuclear DNA content levels of the plants. Shoots from 10 sugarcane varieties (Saccharum spp.) were introduced into two media: MC1, consisting of half-strength Murashige and Skoog (MS) salts and 3% sorbitol, or MC2, similar to the first formulation, but additionally supplemented with 3.8 μM abscisic acid (ABA). The shoots were maintained for up to 12 mo at 18°C in the presence of light. At the end of the period, the explants were inoculated onto multiplication medium containing 0.9 μM 6-benzylaminopurine (BAP) and 0.47 μM kinetin (Kin) for growth recovery. Flow cytometry analysis of shoots was verified at every 6 mo of storage. As a result, we found distinct behaviors of the varieties studied over the storage time, but in general, MC1 provided the greatest explant survival rates, with an average of approximately 80% cultures being able to recover. Once in the recovery media, the explant regrowth was fast, and the ability to multiply shoots was reestablished from the second 30-d subculture. However, by flow cytometry analysis, we observed a decrease in the estimated relative amount of DNA at 12 mo storage for most varieties examined, which was not observed when the monitoring was done at 6 mo. From these results, we conclude that sugarcane plants survived the minimal growth condition; however, maintaining the genotypes for extended periods in vitro may lead to variations in the estimated amount of nuclear DNA and, thus, be at risk of somaclonal variation.

An improved protocol for plant regeneration via somatic embryogenesis was developed using mature macaw palm (Acrocomia aculeata) zygotic embryos as initial explant. For induction of the embryogenic callus (EC), two basic media (BM) were tested consisting of Murashige and Skoog and Eeuwens (Y3) salts with 30 g L−1 sucrose, 0.5 g L−1 glutamine and 2.5 g L−1 Phytagel. The 3,6-dichloro-2-methoxybenzoic acid (dicamba), 4-amino-3,5,6-trichloro-picolinic acid (picloram) and 2,4-dichlorophenoxyacetic acid (2,4-D) auxins were added to the culture media at concentrations of 0, 1.5 or 3.0 mg L−1. After 240 days, the embryogenic calli were transferred to the respective BM media with auxin concentrations reduced to 0.5 or 1.0 mg L−1 in order to differentiate the somatic embryos (SEs). Plant regeneration was performed on the BM media without growth regulators. Embryogenic calli were observed after 180 days of culture and in all treatments with auxin. The Y3 medium showed the best EC formation results (60.8 %). These calli showed yellowish coloration, compact consistency and nodular aspect. After 60 days in differentiation medium, SEs were verified in different stages of development. Histological analysis showed that the SEs were formed from a nodular EC. The SEs generally presented unicellular origin with suspensor formation, and at the end of development, bipolar embryos were observed. The plant regeneration frequency reached levels up to 31.9 % when using induction medium consisting of Y3 associated to 1.5 mg L−1 of 2,4-D and the subsequent auxin reduction to 0.5 mg L−1 in the differentiation stage. Regenerated plants showed normal development, with root and aerial part growth.

In this study, the different stages of somatic embryogenesis (SE) of the African oil palm (Elaeis guineensis Jacq.) were characterized biochemically. The total soluble sugars, starch, total free amino acids, and total proteins were extracted, identified and quantified at various stages of embryogenesis: zygotic embryos (initial explants), primary calluses, embryogenic calluses, calluses with pro-embryos, globular embryos, differentiated somatic embryos, and regenerated plants. It was found that at the onset of induction of SE, the level of soluble sugars in the tissues of the explants fell by half. During this period, the total soluble sugars present in the cultures consisted basically of glucose and fructose. In the process of regeneration and maturation, the concentrations of soluble sugars gradually increased, reaching the highest values in the last two stages of development. At this stage, the disaccharide sucrose accounts for more than 80 % of the composition of total soluble sugars in the explants. Compared to starch, we found that the concentrations thereof in developing tissues are inversely proportional to that of soluble sugars virtually throughout embryogenic development. As for free amino acids, we found that after 30 days of induction until formation of the embryogenic calluses, there is an accentuated synthesis of total free amino acids in the explant tissue. In this stage, there was a significant increase in the levels of alanine and serine in the tissues. However, after the formation of the embryogenic calluses, the levels of total free amino acids present in the cultures become stabile and remain constant until the end of cultivation. Similar results were found for total protein, which also showed a significant increase at the onset of induction, undergoing slight changes during the remainder of the cultivation.

We developed an efficient and simple system for inducing somatic embryogenesis and regenerating plantlets from mature zygotic embryos of oil palm. Embryogenic calli were induced from mature zygotic embryos of oil palm on modified Murashige and Skoog medium with 2,4-dichlorophenoxyacetic acid or picloram, alone or in combination with activated charcoal. The greatest frequency of embryogenic callus induction (97.5%) was obtained by culturing mature zygotic embryos on callus induction medium with 450 μM picloram and 2.5 g L−1 activated charcoal. Embryogenic calli proliferated on a medium with a reduced concentration of picloram. Embryogenic calli were then subcultured on a medium supplemented with 12.3 μM 2-isopentenyladenine and 0.54 μM naphthaleneacetic acid, with subcultures at 4-wk intervals. Somatic embryos were regenerated on a medium with Murashige and Skoog macro- and micronutrients at half-strength concentrations supplemented with 20 g L−1 sucrose, 2.5 g L−1 activated charcoal, and 2.5 g L−1 Phytagel. Detailed histological analysis revealed that somatic embryogenesis followed an indirect pathway. Primary calli were observed after 4–6 wk of culture and progressed to embryogenic calli at 12 wk. Embryogenic cells exhibited dense protoplasm, a high nucleoplasmic ratio, and small starch grains. Proembryos, which seemed to have a multicellular origin, formed after 16–20 wk of culture and successive cell divisions. Differentiated somatic embryos had a haustorium, a plumule, and the first and second foliar sheaths. In differentiated embryos, the radicular protrusion was not apparent because it generally does not appear until after the first true leaves emerge.

An efficient and simple system for inducing somatic embryogenesis and regenerating plantlets from immature zygotic embryos of acai palm (Euterpe oleracea) has been developed. Embryogenic calli (ECs) were induced from immature zygotic embryos of acai palm on Murashige and Skoog (MS) modified medium with 2,4-dichlorophenoxyacetic acid and picloram. Embryogenic frequency was dependent on auxin type and concentration. The optimal concentration of picloram for the high-frequency induction of embryogenic calli (72%) was 225 μM. ECs were then subcultured on a differentiation and maturation medium composed of MS modified medium with 2-isopentenyladenine and naphthaleneacetic acid with subcultures at 4-week intervals. SEs were converted to plants on MS modified medium with half-strength macro- and micronutrients, 20 g l−1 sucrose, and 2.5 g l−1 activated charcoal and gelled with 2.5 g l−1 Phytagel. Detailed morpho anatomical changes during the different stages of somatic embryogenesis were characterized. The development of SEs was asynchronous, and ontogenic studies confirmed that the initial cell divisions occur in the epidermal and subepidermal regions of the zygotic embryos. Broad base attachment of SEs to the epidermis indicates the presence of a suspensor.

Altos custos de produção geralmente limitam o uso comercial da micropropagação. O uso de meios de cultura líquidos é considerado uma solução para a automação e redução de custos. Entretanto, dependendo da cultivar de bananeira, esse processo pode mostrar diferentes níveis de dificuldade, e adaptações nos protocolos são necessárias. Neste estudo, experimentos de diferenciação celular e regeneração de plantas foram desenvolvidos em células em suspensão de banana pela avaliação da densidade inicial de células, meios de cultura e sistemas de imersão temporária. Para tanto, uma sequência de três experimentos foi realizada: o primeiro avaliou os efeitos da densidade celular (0,5; 1 e 2 mL), meios de cultura (M1: 1/2MS, 0,1 g.L-1 de ácido ascórbico, 0,1 g.L-1 de L-prolina, 30 g.L-1 de sacarose e 10 µM de 2iP; M2: MS, 30 g.L-1 de sacarose, 2,2 µM de BAP e 11,4 µM de AIA) e períodos de diferenciação celular (40 e 130 dias); o segundo experimento analisou o efeito do tamanho dos propágulos diferenciados em meio líquido (aprox. 2,5; 5 e 10 mm em diâmetro) na formação de embriões somáticos ou na regeneração de plantas; finalmente, um terceiro experimento avaliou o efeito de sistemas de cultivo com papel-filtro cobrindo o meio de cultura semissólido e sistemas de imersão temporários na diferenciação dos propágulos e na regeneração de plantas. Não foram observadas diferenças significativas entre os meios de diferenciação, porém as melhores diluições de células para a diferenciação foram de 1 e 2 mL/30mL de meio de cultura, enquanto diluições de 0,5 mL/30 mL de meio aumentaram a oxidação celular. A extensão do período de diferenciação de 40 para 130 dias foi importante para produzir maior número de calos/propágulos uniformes e com pelo menos de 10 mm de diâmetro, que puderam ser usados em sistemas de imersão temporária (biorreatores) para a diferenciação de embriões somáticos e regeneração de plantas. Considerando todos os sistemas de regeneração, verificou-se que o uso de meios de regeneração de consistência semissólida com papel-filtro na superfície do meio é o mais responsivo para a diferenciação de embriões somáticos e regeneração de plantas. High production costs generally limit the commercial use of the in vitro micropropagation. The use of liquid media is considered to be the ideal solution for the automation and the production costs reduction. However, depending on the variety, this process can show different levels of difficulty and adaptations in protocols are needed. In this study experiments on cell differentiation and plant regeneration were carried out from banana cell suspension culture, by evaluating the initial cell density, the culture media and the temporary immersion systems. A sequence of three experiments was performed: the first one evaluated the effects of cell density (0.5; 1 and 2), culture media (M1: 1/2MS, 100 g.L-1 ascorbic acid, 100 mg.L-1 L-proline, 30 g.L-1 sucrose and 10 µM 2iP; M2: MS, 30 g.L-1 sucrose, 2,2 µM BA and 11,4 µM IAA) and the period of cells differentiation (40 and 130 days). The second one analyzed the effect of propagules size differentiated in liquid media (approx. 2.5; 5 and 10 mm diameter) on somatic embryo formation or plant regeneration. Finally, a third experiment analyzed the effects of culture systems with filter-paper-covered medium and temporary immersion systems, on propagules differentiation or plant regeneration. The results showed that no differences were found between both differentiation media, and the better cells densities for differentiation were 1 ml and 2 mL/30 mL medium, whereas dilutions of 2 mL/30 mL medium increased cell oxidation. Extending the period in the differentiation medium from 40 to 130 days was important to produce a higher number of uniform embryogenic propagules with 10 mm diameter, which can be used in temporary immersion systems (bioreactors) for embryo and plant regeneration. Considering all the regeneration systems, the semi-solid regeneration medium covered by filter-paper significantly increased the somatic embryo differentiation and plants regeneration.

The objective of this work was to evaluate in vitro storage of Piper aduncum and P. hispidinervum under slow-growth conditions. Shoots were stored at low temperatures (10, 20 and 25°C), and the culture medium was supplemented with osmotic agents (sucrose and mannitol - at 1, 2 and 3%) and abiscisic acid - ABA (0, 0.5, 1.0, 2.0 and 3.0 mg L-1). After six-months of storage, shoots were evaluated for survival and regrowth. Low temperature at 20ºC was effective for the in vitro conservation of P. aduncum and P. hispidinervum shoots. In vitro cultures maintained at 20ºC on MS medium showed 100% survival with slow-growth shoots. The presence of mannitol or ABA, in the culture medium, negatively affected shoot growth, which is evidenced by the low rate of recovered shoots. O objetivo deste trabalho foi avaliar a conservação in vitro de Piper aduncum e P. hispidinervum, em condições de crescimento lento. Os brotos foram armazenados a baixas temperaturas (10, 20 e 25ºC), e o meio de cultura foi suplementado com agentes osmóticos (sucrose e manitol - a 1, 2 e 3%) e ácido abcísico - ABA (0, 0,5, 1,0, 2,0 e 3,0 mg L-1). Após seis meses de armazenamentos os brotos foram avaliados quanto à sobrevivência e à rebrotação. A baixa temperatura de 20ºC foi efetiva para a conservação in vitro de brotos de P. aduncum e P. hispidinervum. Culturas in vitro, mantidas a 20ºC em meio MS apresentaram 100% de sobrevivência com o crescimento lento dos brotos. A presença de manitol ou ABA, no meio de cultura, afetou negativamente o crescimento de brotos, o que foi evidenciado pelo baixo índice de sobrevivência dos brotos.

An efficient procedure has been developed for inducing somatic embryogenesis and regeneration of plants from tissue cultures of oil palm (Elaeis guineensis Jacq.). Thin transverse sections (thin cell layer explants) of different position in the shoot apex and leaf sheath of oil palm were cultivated in Murashige and Skoog (MS) (Physiol Plant 15:473–497, 1962) medium supplemented with 0–450 µM picloram and 2,4-D with 3.0% sucrose, 500 mg L−1 glutamine, and 0.3 g L−1 activated charcoal and gelled with 2.5 g L−1 Phytagel. Embryogenic calluses were evaluated 12 wk after inoculation. Picloram (450 µM) was effective in inducing embryogenic calluses in 41.5% of the basal explants. Embryogenic calluses were maintained on a maturation medium composed of basal media, plus 0.6 µM NAA and 12.30 µM 2iP, 0.3 g L−1 activated charcoal, and 500 mg L−1 glutamine, with subcultures at 4-wk intervals. Somatic embryos were converted to plants on MS medium with macro- and micronutrients at half-strength, 2% sucrose, and 1.0 g L−1 activated charcoal and gelled with 2.5 g L−1 Phytagel.

Research about the use of natural light associated to changes in sucrose levels demonstrated potential in promoting in vitro hardiness of tropical climate species, as well as reducing production costs. However, little is known about physiological and structural changes that happen in the process. This study evaluated the physiological and anatomic performance, and ex vitro survival of micropropagated banana plants in response to cultivation conditions, in the stage of in vitro rooting. Shoots of the 'Caipira' cultivar were cultivated in MS medium, supplemented with 1 mg L-1 NAA and 6 g L-1 agar, in which the following treatments were applied: two sucrose concentrations (15 g L-1 or 30 g L-1) and two cultivation conditions (Natural light - greenhouse and Artificial light - growth chamber). At the end of 45 days, the contents of chlorophyll a, b and total, the relative water content in the tissues, anatomic characteristics and the ex vitro survival were evaluated. Effects of growth environment and sucrose concentration were observed on micropropagated 'Caipira' banana anatomy, physiology and survival. In vitro rooting of the shoots under natural light in the medium containing 15 g L-1 or 30 g L-1 sucrose promoted major alteration in the increase of palisade and spongy parenchyma, as well as reducing leaf water loss and plant death. The results obtained in the present study confirm the potential of the use of natural light as a substitute for artificial light for micropropagation of tropical species.

A realização de pesquisas que possibilitem redução dos custos de produção e ou melhoria na qualidade das mudas micropropagadas tem sido imprescindível para possibilitar a utilização e difusão deste tipo de material propagativo. O objetivo deste trabalho foi avaliar a influência de alterações no ambiente de cultivo sobre o crescimento e anatomia de bananeiras na fase de alongamento/enraizamento in vitro. Para tanto, brotações axilares das cultivares Caipira e Pacovan foram cultivadas em meio MS contendo ANA (1 mg L-1) e agar (6 g L-1), onde foram aplicados os tratamentos. Os tratamentos consistiram de concentrações de sacarose (15 g L-1 e 30 g L-1) e ambientes de cultivo (Natural - casa de vegetação e Artificial - sala de crescimento). No fim de 45 dias, foram determinadas características de crescimento e de anatomia foliar. Houve influência significativa das alterações no ambiente de cultivo in vitro sobre as características avaliadas. Verificou-se que o uso da luz natural associada a 15 g L-1 de sacarose para a cultivar Caipira e 30 g L-1 para a Pacovan pode ser utilizada satisfatoriamente na fase de alongamento/enraizamento in vitro. Maior espessamento dos parênquimas clorofilianos e incremento na densidade estomática são induzidos em ambiente natural. A luz natural como alternativa às lâmapadas fluorescentes, no alongamento/enraizamento in vitro, representa potencial para reduzir os custos de produção e promover melhorias na anatomia foliar das mudas micropropagadas.

Micropropagation via somatic embryogenesis (SE) is one of the forms of propagation of plants and the most commonly recommended method for clonal propagation of palms. Despite the existence of a vast number of works in the literature, SE is still far from being completely mastered and understood, although it is known that callus induction and the use of auxins are fundamental prerequisites for obtaining satisfactory results. In fact, in vitro development of cells and tissues via SE is dependent on different factors, such as plant genotype and type, age, and the physiological and developmental state of the explant and donor plant. External factors include the composition of the medium and the physical cultivation conditions. The interaction between all these factors leads to the induction and expression of a specific mode of cell differentiation and development, which in turn leads to embryogenesis. The present review discusses the main factors involved during somatic embryogenesis of palms. At the same time, a significant number of protocols developed in recent years are compiled to provide readers about the current state of the art on the subject.

O objetivo deste trabalho foi avaliar a manutenção in vitro de acessos de óleo de palma (Elaeis guineenses e E. oleifera) sob condições de crescimento lento. Plantas produzidas pelo resgate de embriões foram submetidas ao meio de cultura 1/2MS, acrescido dos carboidratos sacarose, manitol e sorbitol nas concentrações de 1, 2 e 3%, em 20 e 25±2ºC. Após 12 meses, a temperatura de 20°C retardou o crescimento das plantas. A sacarose é o carboidrato mais adequado para a manutenção da qualidade das plantas, enquanto o manitol e o sorbitol resultam em menor sobrevivência das plantas. The objective of this work was to evaluate the in vitro maintenance of oil palm (Elaeis guineensis and E. oleifera) accessions under slow-growth conditions. Plants produced by embryo rescue were subject to 1/2MS culture medium supplemented with the carbohydrates sucrose, mannitol, and sorbitol at 1, 2, and 3% under 20 and 25±2ºC. After 12 months, the temperature of 20°C reduced plant growth. Sucrose is the most appropriate carbohydrate for maintaining the quality of the plants, whereas mannitol and sorbitol result in a reduced plant survival.

O carvão ativado possui a propriedade de adsorver os compostos fenólicos liberados pela oxidação dos tecidos lesionados durante o cultivo in vitro. O objetivo deste trabalho foi avaliar os efeitos da interação entre o carvão ativado e diferentes concentrações de N6-benzilaminopurina (BAP) na multiplicação in vitro da bananeira, cv. Grande Naine (AAA). O meio de cultura utilizado foi o MS, solidificado com 5 g.L-1 de ágar. O cultivo foi mantido em sala de crescimento a 25±2ºC, fotoperíodo de 16 horas e intensidade luminosa de 30 mmol.m-2s-1. Foram avaliadas a presença e a ausência de carvão ativado (0 e 3 g.L-1) e quatro concentrações de BAP (0; 2; 4 e 6 mg.L-1) no meio de cultura. O delineamento foi inteiramente casualizado, com cinco repetições, em um sistema fatorial 2x4. Os explantes foram avaliados a cada 30 dias, por um período de quatro subcultivos. Após cada subcultivo, o comprimento de brotações, a taxa de multiplicação, o vigor, o nível de oxidação das brotações emitidas e o número de raízes formadas foram avaliados. Independentemente das concentrações de BAP, o carvão ativado influenciou significativamente em todas as variáveis analisadas. De maneira geral, a adição de carvão ativado afetou negativamente a taxa de multiplicação, embora tenha melhorado o vigor e o número de raízes e diminuído a oxidação dos explantes. Na ausência de carvão ativado, o BAP proporcionou as maiores taxas de multiplicação das brotações.

Este trabalho teve por objetivos isolar, caracterizar e identificar bactérias endofíticas contaminantes encontradas em tecidos de batata durante a micropropagação e selecionar antibióticos para o controle in vitro desses microrganismos por meio da determinação da concentração bactericida mínima inibitória. Brotações de batata apresentando contaminação bacteriana durante a etapa de multiplicação in vitro, foram superficialmente esterilizadas e os internódios transferidos para placas de Petri com ágar nutriente, onde permaneceram incubadas a 28°C por até cinco dias. Após purificação, as bactérias foram caracterizadas e identificadas por testes taxonômicos. Um total de oito estirpes bacterianas foram isoladas e identificadas como pertencentes às famílias Acetobacteriaceae (1) e Enterobacteriaceae (2) e aos gêneros Corynebacterium (3), Pseudomonas (1) e Xanthomonas (1). Os melhores resultados para a inibição do crescimento bacteriano foram obtidos com os antibióticos ampicilina, cloranfenicol, estreptomicina e tetraciclina em concentrações que variaram de 32 a 256 mg L-1. This work aimed to isolate, characterize and identify contaminant endophytic bacteria found in potato tissues during the micropropagation and to select antibiotics for in vitro control of these microorganisms by determining the inhibitory minimal bactericidal concentration. Potato shoots presenting bacterial contamination during the in vitro multiplication were superficially sterilized and the internodes transferred to Petri dishes with nutrient agar medium for up to five days at 28°C. After subcultures the grown bacteria were purified and identified through taxonomic tests. A total of eight bacterial endophytic strains were isolated and identified as belonging to Acetobacteriaceae (1) and Enterobacteriaceae (2) families and Corynebacterium (3), Pseudomonas (1) and Xanthomonas (1) genera. The best results for bacterial growth inhibition were obtained with ampicilin, chloramphenicol, streptomycin and tetracycline antibiotics in concentrations ranging from 32 to 256 mg L-1.

O objetivo deste trabalho foi otimizar o crescimento de plantas micropropagadas do porta-enxerto de macieira 'Marubakaido' (Malus prunifolia) em casa de vegetação, por meio da aplicação de ácido giberélico (AG3) por uma, duas, ou três vezes, em intervalos semanais. As concentrações testadas foram: 0, 50, 100, 200, 400, 800 e 1.600 mg L-1. O crescimento das plantas foi avaliado quinzenalmente, por um período de dois meses. O comprimento dos entrenós e a matéria seca da parte aérea das plantas também foram avaliados no final do experimento. Três aplicações de AG3 na concentração de 800 mg L-1 foi o tratamento que proporcionou a maior taxa de crescimento das plantas (912% contra 114% das plantas não-tratadas), além de proporcionar plantas com maior comprimento de entrenós e massa seca da parte aérea. Plantas pulverizadas uma única vez não apresentaram diferenças significativas em nenhuma das variáveis estudadas. Estes resultados sugerem que o uso do AG3 em plantas de macieira, oriundas da micropropagação, melhora o crescimento, embora um número de pelo menos três aplicações, associado com concentrações mais elevadas, seja necessário para melhorar a eficiência deste regulador. Aiming to optimize plant growth of the apple rootstock cultivar Marubakaido (Malus prunifolia) in greenhouse, one-year old plants coming from in vitro cultivation were sprayed once, twice and three times in a 7-day interval with gibberellic acid (GA3). The concentrations of 0, 50, 100, 200, 400, 800 and 1,600 mg L-1 were used. Plant growth was evaluated every two weeks during two months. Internode length, number of buds and the dry mass of the aerial part were also evaluated at the end of the experiment. Three sprays of GA3 at 800 mg L-1 was the best treatment providing the largest rate of plant growth (912% against 114% of non-treated plants) in relation to their initial height, besides providing larger internode length and higher dry matter of aerial parts. Plants sprayed once did not present significant response to GA3 for none of the studied variables. These results suggest that the use of GA3, in apple plants coming from micropropagation, improves the growth, although a number of at least three applications, associated with high concentrations, is necessary to improve the efficiency of this regulator.

O presente trabalho foi realizado no Laboratório de Cultura de Tecidos da EMBRAPA/CPACT, Pelotas-RS, com o objetivo de verificar o comportamento in vitro de duas cultivares de morangueiro em diferentes concentrações do meio MS. Explantes de morangueiro, cultivares Hofla e Tangi provenientes do cultivo in vitro foram cultivados em meio MS, na concentração plena, 3/4 e 1/2 adicionado de sacarose a 30g/l, mio-inositol a 100mg/l e benzilaminopurina (BAP) a 0,005mg/l. Utilizaram-se frascos com capacidade de 250ml, que continham 40ml de meio de cultura, nos quais inocularam-se cinco explantes. O cultivo foi mantido em sala de cultura, onde permaneceu por 32 dias sob fotoperíodo de 16 horas, luminância de 1500 lux e temperatura de 25°C. Os resultados indicaram que a redução na concentração dos sais MS incrementa o percentual de explantes enraizados, aumentando o número de raízes da cultivar Tangi. O maior comprimento médio de raízes foi obtido com a cultivar Hofla na concentração 3/4 e 1/2 do meio MS. Não se observaram diferenças no desenvolvimento das plântulas, entre as cultivares, com a redução das concentrações do meio MS. The present work was carried out in the Tissue Culture Laboratory EMBRAPA/CPACT, Pelotas-RS, with the objective of verifying the behaviour in vitro of two cultivars of strawberry on different MS medium concentration. Strawberry explants, Hofla and Tangi cultivars coming from in vitro culture were tested on MS medium in the full, 3/4 and 1/2 strength suplemented with 30g/l sucrose, 100mg/l myo-inositol and 0.005mg/l benzylanimopurine (BA). Flasks (250ml) containing 40ml of medium culture with five explants per flasks were used. Cultures were maintained in a growth room at 25°C with a photoperiod of 16 h at 1.5 Klux for 32 days. Results indicated that the reduction in MS salts improved rooting explant by increasing the number of roots of the Tangi cultivar. A large root length was obtained with the Hofla cultivar in the 3/4 and 1/2 MS concentration. It was not observed any difference in the development of the plantlets among the cultivars due to the reduction in MS salts.

The objective of this work was to evaluate the phytotoxicity of a plant vitrification solution (PVS2), and the survival of shoot tips of the sugarcane variety SP716949, after cryopreservation by droplet-vitrification. Shoot tips were precultured for 24 hours in MS medium containing 0.3 mol L-1 sucrose, and exposed to PVS2 for 0, 20 or 30 min. Shoot tips were then immersed in liquid nitrogen. Thawing was fast in concentrated sucrose solution (1.2 mol L-1). PVS2 is a nontoxic to shoot tips, which in turn are sensitive to liquid nitrogen. The best results occurred when shoot tips were maintained for up to 20 min in PVS2 solution, before freezing, with 20% survival.

The objective of this study was to morpho-anatomically characterizenodular embryogenic calluses from zygotic embryos of peach palm during the induction of somatic embryogenesis. Immature zygotic embryos were pre-treated in MS medium added to Picloram and 2,4-D (25 μM) and BAP (0, 5, 10 μM). After three months, primary calluses were transferred to MS induction medium added to Picloram and 2,4-D (450 μM). After six months, the embryogenic calluses were then histologically analyzed and cultivated in the maturation medium. The competent tissues of the zygotic embryos differentiated embryogenic calluses under action of both Picloram and 2,4-D auxins (450 μM), where the presence of multi-granular structures were observed. Histological observations showed that in the nodular embryogenic calluses, the outlying parenchymal cells exhibit cellular characteristics of high mitotic activity. Differentiation of tracheal elements exists in embryogenic calluses connecting the callus to the explant. The evaluated cytokinin/auxin interaction influences the development of embryogenic calluses and globular structures.O objetivo deste trabalho foi caracterizar morfoanatomicamente calos nodulares embriogênicos originados de embriões zigóticos de pupunheira durante a indução da embriogênese somática. Embriões zigóticos imaturos de pupunha foram inicialmente pré-tratados em meio de cultura MS, solidificado com 2,5 g L-1 de phytagel® e suplementado com Picloram e 2,4-D na concentração de 25 μM e BAP (0, 5, 10 μM). Após três meses, os calos primários foram transferidos para meio de indução, com Picloram e 2,4-D (450 μM). Após seis meses, os calosnodulares embriogênicos formados foram então analisados histologicamente e repicados para o meio de maturação para a progressão das estruturas multigranulares embriogênicas. Verificou-seque os tecidos competentes dos embriões zigóticos imaturos diferenciaram nódulos embriogênicos pela ação de ambas as auxinas (Pi e 2,4-D) em 450 μM. Observações histológicas mostraram que, nos nódulos embriogênicos, as células parenquimáticas mais periféricas exibem características celulares de alta atividade mitótica. Existe diferenciação de elementos traqueais nos calos embriogênicos conectando o calo ao explante. A interação citocinina/auxina influencia o desenvolvimento dos calos embriogênicos e das estruturas globulares.

The development of more efficient and productive systems for pre-basic seed potato production would improve the quality of the propagative material used by the potato growers, directly affecting the crop yields. A two-year experiment was carried out to evaluate the potato pre-basic seed production by two types of hydroponic systems (fibrocement tiles and articulated PVC gutters), two cultivars (`Baronesa` and `Eliza`) and two types of propagative material (plants coming from in vitro culture and minitubers). The PVC gutters system was highly efficient. When using minitubers, this system reached multiplication rates up to 74 tubers per plant. Minitubers were more productive than in vitro plants, independent of cultivar and hydroponic system utilized.Um experimento realizado por dois anos consecutivos avaliou a produção de sementes pré-básicas de batata por meio de sistemas de cultivo hidropônico. O trabalho testou a combinação de dois sistemas de cultivo (telha de fibrocimento e calhas de PVC articuladas), duas cultivares (Baronesa e Eliza) e dois tipos de material propagativo (plântulas oriundas do cultivo in vitro e minitubérculos). O sistema de calhas de PVC foi altamente eficiente. Quando foi utilizado minitubérculos, este sistema alcançou taxas de multiplicação de até 74 tubérculos por planta. De modo geral, o uso de minitubérculos como material propagativo apresentou os melhores resultados de produtividade quando comparada ao material in vitro, independentemente da cultivar e sistemas hidropônicos utilizados.

O objetivo deste trabalho foi avaliar a tolerância de sementes de dendezeiro (Elaeis guineensis) à criopreservação. Cinco genótipos - CM589, C7201, C2528, C2001, C2501 - foram avaliados quanto à exposição ao nitrogênio líquido por sete dias. Os tratamentos foram repetidos três vezes e cada repetição foi formada por dez sementes. Cortes anatômicos foram realizados para comparação do efeito dos tratamentos nos embriões durante a germinação. A exposição ao nitrogênio líquido acelerou a germinação das sementes do genótipo CM589 e aumentou o potencial de germinação das sementes do genótipo C2528. A exposição ao nitrogênio líquido não teve efeito no genótipo C2501 e reduziu a germinação das sementes do genótipo C7201. A exposição ao nitrogênio líquido não interferiu na diferenciação e no desenvolvimento dos tecidos embrionários durante a germinação. The aim of this work was to evaluate the oil palm (Elaeis guineensis) seed tolerance to cryopreservation. Five genotypes (CM589, C7201, C2528, C2001, and C2501) were evaluated with or without exposure to liquid nitrogen for seven days. Treatments were replicated three times with ten seeds per replicate. Serial anatomical cuts were made to compare the effect of treatments on zygotic embryos. For CM589 and C2528, the exposition to liquid nitrogen accelerated and increased seed germination, respectively. For C2501, liquid nitrogen had no effect. For C7201, liquid nitrogen reduced seed germination (90.7%) compared to the check (100%). Anatomically, the liquid nitrogen did not interfere with embryonic tissue differentiation or development during germination.

Species of the genus Mentha produce essential oils which are widely used in pharmaceutical and cosmetic industries. Current study evaluates the potential for in vitro propagation and estimates mass production of plantlets of Mentha species. Nine species ( M. piperita, M. suaveolens, M. canadensis, M. longiflora, M. aquatica, M. arvensis, Mentha x gracilis, M. gracilis and M. spicata ) were propagated with five successive 30-day subcultures in MS medium supplemented with NAA (0.05 µM) and BAP (4.4 µM). Shoots were rooted in MS with IBA, IAA or NAA (0.0; 0.25; 0.5; 2.5 or 5.0 µM). The rooted plantlets were finally acclimatized in a greenhouse. Studied species increased in multiplication rates between 4.2 and 9.0-fold per month. M. piperita , M. longiflora , M. arvensis , M. x gracilis and M. gracilis showed the greatest potential for plantlet production since the estimated production varied between 6,000 and 27,000 plantlets after five 30-days subcultures. The addition of auxin to the medium did not influence root induction. However, IAA at a concentration of 5 µM provided the best results for root length and fresh weight, with averages 11.1 cm and 0.16 g, respectively. Survival of plantlets reached 100% during the greenhouse acclimatization process.

A sacaca é uma planta medicinal do bioma Amazônico e tem sido considerada como substituta do pau-rosa (Aniba roseodora) na produção de linalol. Este trabalho objetivou avaliar a propagação vegetativa in vitro de sacaca, incluindo o estabelecimento de propágulos do campo, protocolos de descontaminação e a determinação de taxas de multiplicação, além de descrever aspectos limitantes da cultura durante os trabalhos in vitro. Foram utilizadas microestacas de 1,0 cm, com uma gema axilar, coletadas de plantas adultas do campo. Tratamentos de desinfestação foram testados no estabelecimento, além de se avaliar a influência do mês do ano da coleta sobre as taxas de contaminação. Após desinfestadas, as microestacas foram inoculadas em tubos de ensaio com meio MS, suplementado com BAP (0, 1, 2 e 3 mg L-1) e AG3 (0 e 0,5 mg L-1). Foi obtido o estabelecimento in vitro da sacaca com 41,9% das microestacas brotadas. A taxa de contaminação alcançou 58,1% (65,4% de origem fúngica e 34,6% de origem bacteriana), com maior ocorrência quando os propágulos foram coletados entre os meses de outubro e janeiro, os mais chuvosos da região amazônica. O aumento nas concentrações de BAP e AG3 no meio de cultura melhorou as taxas de multiplicação do material. Apesar dos resultados obtidos, a espécie apresenta uma série de peculiaridades e limitações ao cultivo in vitro que foram identificadas e relatadas neste trabalho.

O objetivo deste trabalho foi avaliar o efeito de carboidratos e do ácido acetilsalicílico (AAS) na preservação in vitro da batata (Solanum tuberosum L.), cultivar Macaca. Brotações de 1,5 a 2,0 cm de comprimento foram transferidas para meio de MS, acrescido de mio-inositol (100 mg L-1) e ágar (6 g L-1). Testaram-se duas fontes de carboidrato, sacarose e manitol (87,6 mM), e cinco concentrações de AAS (0, 30, 60, 90 e 120 mg L-1). O delineamento foi em blocos casualizados com quatro repetições por tratamento e cada repetição formada por oito tubos de ensaio com uma brotação. O material foi mantido à temperatura de 25±2ºC, fotoperíodo de 16 horas e radiação de 19 miE m-2 s-1. O crescimento e o número de gemas nas hastes foram avaliados por três meses. Passados nove meses, a sobrevivência e o número de microtubérculos também foram avaliados. O uso de manitol, associado às concentrações a partir de 30 mg L-1 de AAS, proporcionou menor crescimento e formação de gemas nas hastes. No meio suplementado com sacarose, a sobrevivência e o número de microtubérculos foram maiores, independentemente das concentrações de AAS utilizadas, após nove meses de cultivo. The aim of this work was to evaluate the effect of carbohydrates and acetyl salicylic acid (ASA) during the in vitro storage of potato (Solanum tuberosum L.), cultivar Macaca. Stems derived from in vitro cultures were cut into 1.5 to 2.0 cm segments and inoculated in a MS medium supplemented with myo-inositol (100 mg L-1) and agar (6 g L-1). Sucrose and mannitol 87.6 mM and five ASA concentrations (0, 30, 60, 90 and 120 mg L-1) were tested. The stems were cultured on 10 mL medium in test tubes (20 x 150 mm) and incubated in a growth chamber at 25±2ºC, 16 hour photoperiod and 19 muE m-2 s-1 radiation. The growth and the bud number formed in the stems for a period of three months were evaluated. Nine months later the survival percentage and the number of microtubers formed were also evaluated. It was observed that the mannitol, associated with 30 mg L-1 of ASA provided the smallest growth and bud formation after three months of storage. The survival and the microtubers amount were larger when the stems were maintained in the medium supplemented with sucrose, apart from the ASA concentration, after nine months of storage.

Aiming to improve plant growth of the apple rootstock cultivar Marubakaido (Malus prunifolia) in greenhouse, 1-year-old plants were sprayed once, twice, and three times in a 7-day interval with gibberellic acid (GA3) in the following concentrations: 0, 50, 100, 200, 400, 800 and 1600 mg•L-1. The plant growth was evaluated every 2 weeks during 2 months. The internode length, bud number, and the dry weight of the aerial part were also evaluated at the end of the experiment. It was verified that GA3 sprayed at 800 mg•L-1 by three times consecutively was the best treatment presenting the largest rate of plants growth (912% against 114% of nontreated plants) in relation to their initial height, besides providing larger internode length and dry matter weight of the aerial parts. However, using this regulator did not affect the plant bud number. Plants sprayed once did not present significant response to GA3 for any of the studied variables. These results suggest that the use of GA3 in 1-year-old apple plants reactivates growth, although, the increase in the number of applications associated with higher doses is necessary to improve the efficiency of this product.