Germination Of Zygotic Embryos Research Articles

Nodal segments and zygotic embryos in culture media for the in vitro propagation of tamarind

There has been a lack of research on the propagation methods of tamarind, hindering the availability and supply of its products. Considering the nutraceutical potential of tamarind and the long-time required to initiate production, this study aimed to evaluate the establishment of nodal segments and the germination of in vitro zygotic embryos of tamarind plants in culture media, salt concentrations, and activated charcoal, aiming at the establishment of an in vitro propagation protocol. For this purpose, MS and WPM media with 25, 50, 75 and 100% salt concentrations were used both with and without activated charcoal (2 g L-1) for the inoculation of nodal segments and zygotic embryos of tamarind. The experiment was conducted in a completely randomized experimental design, in a 2 x 4 x 2 factorial scheme (culture media x salt concentrations x activated charcoal) with 20 replications. It was observed that the in vitro establishment of tamarind nodal segments is viable when using the MS medium with 75% of salts plus 2 g L-1 of activated charcoal and that for the germination of zygotic embryos there was no influence of the treatments. It was also observed that in order to increase the length of the formed plantlets, the MS and WPM media can be employed with 75% of salts.

Somatic embryogenesis to overcome low seed viability and conserve wild banana (Ensete superbum (Roxb.) Cheesman)

The seed viability, ex vitro germination, and percentage of in vitro zygotic embryo germination were found to be very low in Ensete superbum (Roxb.) Cheesman. Only 33.33% of seeds were viable, and the ex vitro germination percentage was only 5%, while the percentage of in vitro zygotic embryo germination was 33%. Somatic embryogenesis experiments produced competent callus on Murashige and Skoog (MS) medium supplemented with 2.5 mg L−1 2,4-D and 3 mg L−1 BAP from inflorescence explants. The embryogenic callus produced the maximum number of somatic embryos on MS basal medium kept in a dark chamber for 15 wk. Half-strength MS medium supplemented with 500 mg L−1 glutamine was optimal for somatic embryo germination and development of plantlets. Regenerated plants had 80 to 90% survival rate. Therefore, somatic embryogenesis can be considered as an efficient method to overcome a drastic reduction in population and to achieve germplasm conservation.

Optimizing embryo age and media for enhancing hybrid seedling recovery in sour orange (Citrus aurantium) × Sacaton citrumelo (C. paradisi × Poncirus trifoliata) crosses through embryo rescue

AbstractIn citrus, development of new hybrids is difficult due to failure of the germination of zygotic embryos. Hence, this study was conducted to standardize embryo age and media for maximizing the germination and subsequent seedling growth in sour orange × Sacaton citrumelo crosses followed by the identification of simple sequence repeats (SSR) markers for distinguishing the hybrids. A factorial experiment in complete randomized design was conducted with two each embryo age (110–120 and 130–140 days after pollination) and culture media (G‐B5 supplemented with 1.5 mg/L GA3 plus malt extract and G‐B5 plus malt extract) for in vitro embryo culture of sour orange × Sacaton citrumelo progenies. Older embryos germinated well in both media, though highest on M1 medium (100%). In fact, M1 medium gave higher plantlet survival in both age groups. The seedling growth of older embryos had highest root length (37.80 mm) and shoot length (24.20 mm) in M1 medium at 60 days after inoculation (DAI). Three SSR markers (TAA45, CAC15 and CAC39) showed polymorphism between female and male parents and were able to identify their hybrids.

Effect of culture media, plant growth regulators and genotypes on growth and developmental stages of oil palm (Elaeis guineensis Jacq.) zygotic embryos

Oil palm (Elaeis guineensis Jacq.) has become the largest traded vegetable oil in the world due to its innumerable uses and its huge economic importance. Which increases the requirement of quality seedling but the conventional seed production limits the commercial seed production with its long germination period and low germination rate. In this context in vitro germination of zygotic embryo could be a promising alternative. Hence in this study the effect of culturing media, plant growth regulators and genotypes were assessed on in vitro regeneration and plantlet development of oil palm zygotic embryos. Zygotic embryos of four elite genotypes were cultured on MS, N6 and Y3 media, with or without plant growth regulators (NAA, BA and GA3-0.2mg/lt). There was no effect of culture media, plant growth regulators and genotypes on germination of zygotic embryos. Whereas on the growth and development of in vitro plantlets, there was a significant effect of culture media and genotypes. Where culture media N6 performs well and Y3 has shown more abnormality. In case of genotypes, genotypes G1 and G2 shown better performance when compared to genotypes G3 and G4. The effect of plant growth regulators on germination and plant growth was non significant.

In vitro culture of zygotic embryos and seeds of Caesalpinia ferrea Martius

ABSTRACT The aim of this study was to evaluate the in vitro germination of zygotic embryos and seeds of Caesalpinia ferrea Martius and the morphogenetic responses of the explants to different concentrations of growth regulators. Seeds and zygotic embryos were inoculated in MS culture medium and kept in a growth room at a temperature of 25 ± 2 ºC for 16 hours of photoperiod for 30 days. The seeds had a higher in vitro germination rate than the explants from zygotic embryos. However, zygotic embryos in MS medium supplemented with 0.9 mg L-1 BAP had the highest percentage of regeneration (50%), number of shoots (3.25), buds (2.85) and leaves (3.15), multiplication rate (27.75), and length of shoots (1.96 cm). The in vitro culture of zygotic embryos and seeds made possible the multiplication of a higher number of healthy seedlings. Thus, it can be used as an alternative technique for the propagation of this species.

The role of arginine metabolic pathway during embryogenesis and germination in maritime pine (Pinus pinaster Ait.).

Vegetative propagation through somatic embryogenesis is critical in conifer biotechnology towards multivarietal forestry that uses elite varieties to cope with environmental and socio-economic issues. An important and still sub-optimal process during in vitro maturation of somatic embryos (SE) is the biosynthesis and deposition of storage proteins, which are rich in amino acids with high nitrogen (N) content, such as arginine. Mobilization of these N-rich proteins is essential for the germination and production of vigorous somatic seedlings. Somatic embryos accumulate lower levels of N reserves than zygotic embryos (ZE) at a similar stage of development. To understand the molecular basis for this difference, the arginine metabolic pathway has been characterized in maritime pine (Pinus pinaster Ait.). The genes involved in arginine metabolism have been identified and GFP-fusion constructs were used to locate the enzymes in different cellular compartments and clarify their metabolic roles during embryogenesis and germination. Analysis of gene expression during somatic embryo maturation revealed high levels of transcripts for genes involved in the biosynthesis and metabolic utilization of arginine. By contrast, enhanced expression levels were only observed during the last stages of maturation and germination of ZE, consistent with the adequate accumulation and mobilization of protein reserves. These results suggest that arginine metabolism is unbalanced in SE (simultaneous biosynthesis and degradation of arginine) and could explain the lower accumulation of storage proteins observed during the late stages of somatic embryogenesis.

In vitro germination of zygotic embryos excised from cryopreserved endocarps of queen palm (Syagrus romanzoffiana (Cham.) Glassman)

Queen palm (Syagrus romanzoffiana [Cham.] Glassman) is a palm species best known as an ornamental tree for urban landscaping, but recently, it has been evaluated as a potential crop for biofuel production. The objective of the present work was to establish a cryopreservation technique for queen palm to ensure long-term conservation of this species. The cryopreservation protocol consisted of direct immersion in liquid nitrogen (LN) of whole endocarps with water contents ranging from 5.5 to 10.9%, followed by slow thawing at room temperature (25 ± 2°C) excision and in vitro culture of zygotic embryos. Viability of zygotic embryos isolated from endocarps with different water contents was evaluated before (control) and after freezing in LN using in vitro culture on Woody Plant Medium (WPM) medium. Germination percentages of zygotic embryos isolated from endocarps stored in LN varied from 84 to 93%, whereas those isolated from controls ranged from 55 to 71%. Germination rates were significantly higher for zygotic embryos excised from cryopreserved endocarps. The water content of control or frozen endocarps did not have a significant effect on germination percentages of zygotic embryos. Zygotic embryos excised from endocarps following cryopreservation in liquid nitrogen developed into normal plantlets after in vitro culture. The technique tested is simple, efficient, and can be used in plant gene banks as a routine approach for long-term conservation of queen palm germplasm.

Detection of lethal yellowing phytoplasma in coconut plantlets obtained through in vitro germination of zygotic embryos from the seeds of infected palms

AbstractLethal yellowing (LY) is a disease caused by 16SrIV phytoplasmas that has devastated coconut plantations in the Americas. An alternative means of phytoplasma spread is through seeds. Therefore, we used a novel approach based on plumules from the embryos of LY‐diseased coconut palms. We cultured the plumules in vitro to determine the presence of phytoplasma DNA in the plantlets. In the first assay, 185 embryos were obtained. The results showed positive detection in 20 samples (11%) with the nested PCR and in 59 samples (32%) with the TaqMan real‐time PCR. A second assay was designed to trace plumules to their respective embryos and haustorial tissues to determine whether they had derived from an embryo with positive LY detection; a total of 124 embryos were obtained. The results showed no positive detection with the nested PCR and positive detection in 42 of the haustorial tissue samples (32%) with the TaqMan real‐time PCR. The 124 plumules isolated from the embryos were cultivated under in vitro conditions and divided into two groups. Group A was followed for shoot formation and Group B was followed to the plantlet stage. After 3 months of cultivation, 33 cultures (50%) within Group A became necrotic; the rest were analysed to evaluate LY phytoplasma DNA with the TaqMan real‐time PCR assay and 14 (42%) tested positive. After 18 months of cultivation, 20 cultures (34%) within Group B became necrotic. The rest were analysed for the detection of the LY phytoplasma DNA, and 15 and 11 (39% and 29%) of the samples tested positive with the TaqMan real‐time PCR and nested PCR assays, respectively. Blast analysis of the sequenced products revealed that the sequences showed 99% homology with LY‐phytoplasma subgroup 16SrIV‐A. The results presented here demonstrate, for the first time, the occurrence of the transmission of LY phytoplasmas from coconut embryos to plantlets.

In vitro germination of zygotic embryos of hybrid BRS Manicoré (E. guineensis X E. oleifera).

The interspecific oil palm hybrid BRS Manicoré (E. guineensis x E. oleifera) has superior agronomic characteristics. However, the germination rate is low (30%) and the process is slow when the seeds are sown in a conventional form. The purpose of this study was to optimize the in vitro germination of zygotic embryos of this hybrid comparing seed lots. The viability of zygotic embryos was evaluated by the tetrazolium test (0.075%) for 4 h. The embryos were cultured on MS and Y3 culture media, with and without the addition of NaH2PO4, as well as on MS, MS1/2 and N6 medium. In MS medium containing NaH2PO4, the germination rate was increased from 40 to 70% in comparison with the medium without sodium phosphate. The comparison between the culture media MS, MS 1/2, N6 and Y3 showed that 75% of zygotic embryos cultured in the Y3 medium formed whole plants (with roots and shoots defined), a higher percentage than embryos cultured on MS, MS 1/2 and N6 media (46, 35 and 17% respectively). In the same Y3 culture medium, the embryos were larger (36% ≥ 2 cm and 30% ≥ 5 cm) than in the other media. Results obtained by the tetrazolium test were similar to those of germination, showing the effect of the genotype of each seed lot. For the germination and development of plantlets it is essential to add NaH2PO4 to a culture medium containing no phosphate or with a low phosphate concentration.

Conservação in vitro de Erythrina velutina a partir de embriões zigóticos

Erythrina velutina is native from the Caatinga domain, which has been heavily affected by the exploitation of natural resources. Thus, the aim of this study was to evaluate the induction of buds from nodal segments of in vitro germinated plants, aiming at the conservation of E. velutina. In the experiment I, intact seeds and zygotic embryos were inoculated in WPM culture and the number of buds, leaves and roots, germination percentage, shoot length and percentage of normal plants were analyzed. In the experiment II, the nodal segments of plants from germination of zygotic embryos in vitro were inoculated in WPM culture supplemented with BAP and CIN [0.0, 10.0, 20.0, 30.0 and 40.0 µM] and percentage of responsive explants to form buds, number of shoots and leaves, shoot length and the percentage of callus formation were analyzed. The cultivation of zygotic embryos provided more vigorous and uniform plants, with more gems than those obtained from the germination of intact seeds. The concentration of 20 µM of BAP is indicated for the regeneration of plants from zygotic embryos of E. velutina; with this concentration, an average of 2.78 shoots/explant was obtained.

Investigations on ex situ conservation of selected Australian palms

Of the approximately 2500 species of Arecaceae, only a very small number has been studied extensively due to their global economic significance. This includes date palm, oil palm and coconut. Other palm species are generally under-studied since they are not well known outside of their natural distribution despite the likelihood of contributing considerably to the local economy. While the western culture generally regards palms as ornamentals, palm and palm products are an integral part of life in the tropics and sub-tropics. Over-exploitation and other land-use pressures in these regions have resulted in the disappearance of many species from wild stands; while climate change coupled with stresses like weeds is forecasted to exacerbate the rate of loss. Consequently, Arecaceae has been increasingly recognised as a susceptible family with 65% of the species recorded by International Union for Conservation of Nature (IUCN) under the LSQUOthreatenedRSQUO category, hence the need for conservation and propagation. A major hurdle for in situ conservation of palms is germination, which can take up to years, while the absence of lateral buds impedes conventional vegetative propagation. This study focuses on the development of ex situ conservation methods for selected Australian palms in the genera Livistona and Archontophoenix. This includes investigations on seed storage behaviour and in vitro germination of zygotic embryos as a precursor to developing cryopreservation techniques. The results of this investigation indicate that A. cunninghamiana seeds are desiccation-sensitive whilst L. decora and L. nitida seeds are desiccation-tolerant. This suggests that seeds of these Livistona spp. may be stored using standard seed storage methods and will allow for collection and long-term seed storage of these species. This is currently being tested. For A. cunninghamiana, which is desiccation sensitive, further investigations for viability at a range of moisture contents and temperatures, including liquid nitrogen storage to try to develop a reliable seed storage protocol are currently being done. As an alternative to seed storage, in vitro germination of zygotic embryos has been investigated as a precursor to a possible cryopreservation of zygotic embryos. The results indicate that germination of zygotic embryos is both rapid and effective and this method will now be used in the development of A. cunninghamiana embryos.

In vitro development and acclimatization of dendezeiro (Elaeis guineensis)

Fruits and almond from the dendezeiro, oil palmbelonging to the Elaeis genus,are widely used for the production of cookingoils or for the pharmaceutical and cosmetic industries.In the last decade, this oil palm also emerged as a promising source for commercialbiofuel production. This study evaluated the effect of different culture media, MS (MURASHIGUE AND SKOOG) and Y3 (EEUWENS)and carbohydrates duringin vitro germination of zygotic embryos, the effect of growth regulators GA3, NAA and BA Ponin vitro seedling development, and the survival rate of acclimatized seedlingsof Manicoré hybrid (Elaeis oleifera x E. guineensis). Zygotic embryos were inoculated on MS and modified Y3 media, supplemented with different sucrose concentrations (30, 45, and 60 gL-1) or sorbitol (36 gL-1), and the germination rate was evaluated after 30 days. Subsequently, seedlings were transferred to modified Y3 culture medium supplemented with differentGA3 concentrations (3.5 and 7 mgL-1) or without it, combined or not with 1 mgL-1 of NAA, 5 mgL-1 of BAP.The highest germinationpercentage of germinated embryos (92%) was observed in MS medium supplemented with 36 gL-1 sorbitol. Culture media supplemented with growth regulatorsGA3, NAA and BAP promoted greater shoot lengththan control media. Rooted seedlings showed high survival percentage (85%) during acclimatization.

English

Oil palm cultivation has acquired economic importance due to rising demand for vegetable oils used in food, pharmaceutical, cosmetic and most recently, in biofuel industries. However, the commercial production increase of oil palm is limited by plantlet production, as it primarily uses seeds that require a long germination period and have low germination rates. In this study we evaluated the effect of embryo age (time after pollination), culture media and presence of carbohydrates on in vitro germination of zygotic embryos of oil palm (Elaeis guineensis Jacq.) Manicoré hybrid. Embryos at 80, 90, 100 and 110 days post-anthesis were inoculated in MS medium or modified Y3 medium, with or without 3% sucrose. Media were renewed after 30 days of inoculation, and plantlets were kept for 45 days until collection for histological analyses. The embryos did not germinate in medium without sucrose. Embryos of 100 days post-anthesis in MS medium showed the best result for germination rate (88%), which did not differ statistically from Y3 medium. As for the parameters, 90-day embryos showed better results for number and length of roots in Y3 medium. It was concluded that 90-day embryos cultivated in Y3 medium generate plantlets in better conditions to be transferred to acclimatization.   Key words: Oil palm (Elaeis guineensis Jacq.), germination, sucrose, Y3 medium, MS, anatomy, embryo culture.

In Vitro Zygotic Embryo Germination and Somatic Embryogenesis through Cotyledonary Explants of Paeonia lactiflora Pall.

A simple and efficient protocol was developed for somatic embryogenesis from the cotyledon explant of Paeonia lactiflora Pall. Seeds of peony obtained from fieldgrown plants were disinfested and zygotic embryos were excised. For germination, excised embryos were cultured on the Murashige and Skoog (MS) medium supplemented with 3% (w/v) sucrose, 0.8% (w/v) agar, and different concentrations of N 6 benzyl-adenine (BA) and gibberellic acid (GA₃). The greatest germination percentage (95%) was observed when embryos were cultured on the MS medium with 1.0 mg·L -1 BA and 0.5 mg·L -1 GA₃, and maintained at 25 ± 2°C under a 16 h photoperiod. Thirty days old cotyledon explants were cultured on the MS medium supplemented with different concentrations and combinations of plant growth regulators viz., BA, GA₃, 2,4-dichlorophenoxyacetic acid (2,4-D), and a-naphthalene acetic acid (NAA). After 90 days, the globular embryos were directly formed on the surface of explants. The highest frequency of somatic embryo induction (72.5) was obtained on the MS medium with 3.0 mg·L -1 BA, 1.0 mg·L -1 NAA, 1.0 mg·L -1 GA₃, and 0.1% (w/v) activated charcoal (AC), with a mean number of 14 embryos per explant. Maturation of globular embryos into heart- and torpedo-shape was observed on the same medium. When the torpedo-shaped embryos were transferred onto the same MS medium supplemented with 3.0 mg·L -1 BA, 1.0 mg·L -1 NAA, 1.0 mg·L -1 GA₃, and 0.1% (w/v) AC, secondary somatic embryos were observed on the surface of primary somatic embryos. When the embryos were transferred to the MS medium supplemented with 1.0mg·L -1 each of BA and GA₃, all of them converted into plantlets, but their growth was very slow.

In vitro germination and embryogenic competence acquisition of Euterpe edulis Martius immature zygotic embryos

This study evaluated different aspects of in vitro germination and embryogenic competence of immature zygotic embryos of E. edulis. The embryos germinated on full or half-strength MS (MS or MS/2) medium combined with sucrose (20, 30 and 40 g L-1). The effect of calcium chloride concentrations (0, 2, 4, 8, and 12 mM) on the induction of somatic embryogenesis was tested. The embryos were germinated on MS or MS/2. Germination of zygotic embryos and the number of roots per plantlet were not affected by the culture medium and sucrose concentration. Plantlet height and fresh weight were influenced by both; the difference was greatest in MS medium with 40 g L-1 sucrose. The induction of somatic embryogenesis was not influenced by doses of calcium chloride, whereas the number of somatic embryos formed was affected. The germination capacity of somatic embryos of heart-of-palm tree was not influenced by the media tested.

Aplicação de análogo de brassinosteroide (Biobras 16®) sobre a germinação e crescimento in vitro de embriões zigóticos e aclimatização de plântulas de bocaiuva

Apresentam-se resultados de pesquisa experimental que avaliou o crescimento in vitro de embriões zigóticos e aclimatização de plântulas de bocaiuva (Acrocomia aculeata) cultivadas em diferentes concentrações (0,0; 0,001; 0,005; 0,01; 0,05; 0,1; 0,5 e 1mg L-1) de análogo de brassinosteroide (Biobras 16®). O trabalho buscou verificar se a aplicação de Biobras 16® influencia positivamente na taxa de germinação dos embriões zigóticos de Acrocomia aculeata e se promove o crescimento e desenvolvimento das plântulas e, consequentemente, afeta o número de plântulas normais. A aplicação de Biobras 16® não promoveu acréscimo no percentual de germinação, porém, estimulou a formação de plântulas normais. |O efeito positivo de Biobras 16® foi observado apenas na primeira fase, não sendo observado nas demais fases de crescimento avaliadas.

Rapid in vitro germination of zygotic embryos of fluted pumpkin (Telfairia occidentalis Hook. f.)

SummaryFluted pumpkin, Telfairia occidentalis, is becoming an important regional vegetable for its food and medicinal uses. The recalcitrant nature of its seed makes conservation difficult and in vitro techniques may be a viable option for conservation. A pilot study was conducted on the effects of different concentrations of a commercial bleach [3.85% (w/v) sodium hypochlorite] for surface sterilisation of T. occidentalis seed. The optimum concentration [25% (v/v)] was then used as a basis to investigate the responses of mature embryonic axes of T. occidentalis to different concentrations of kinetin (Kin; 0, 1.0, or 2.0 mg l–1) and 1-naphthaleneacetic acid (NAA; 0, 0.5, or 1.0 mg l–1) combined in a factorial design. The results of the first experiments indicated that commercial bleach at 25% (v/v) resulted in the lowest contamination of explants (10%), with no evident injury to the embryonic axes. The results revealed that root emergence started 3 d after initiation (DAI) only on Murashige and Skoog medium (MS) with no added plant growth regulator (PGR), and that, by 12 DAI, all media supported the rooting of explants. The highest rooting percentage (69%) was observed at 15 DAI on MS medium with 0.5 mg l–1 NAA, without Kin. However, shoot emergence started at 9 DAI on PGR-free MS medium, on MS with 0.5 mg l–1 NAA, or on MS plus 1.0 mg l–1 Kin. The highest shooting percentage (91%) of explants was observed with 0.5 mg l–1 NAA at 21 DAI. Considering all other growth parameters, MS medium supplemented with 0.5 mg l–1 NAA was found to be best for the germination of embryonic axes of T. occidentalis.

Effect of plant growth regulators on in vitro germination of coffee zygotic embryos

Coffee propagation is performed by seeding. However, germination in coffee seed is slow and uneven. Indeed, the production of plants in field is affected by environmental factors, which retards the germination rates and, in consequence, the number of plants obtained. Plant tissue culture provides the possibility of applying different growing conditions, such as different types of media and using phytoregulators, to induce a response in order to shorten zygotic embryo germination times. Therefore, due to limited understanding of growing zygotic embryos of coffee, we evaluated the effect of certain plant growth regulators on zygotic embryo germination of Coffea arabica . To study germination times, we evaluated the effects of culture media with incubation either at photoperiod or darkness and with certain plant growth regulators [gibberellic acid (GA), abscisic acid (ABA), indole-3-butyric acid (IBA), naphthalene acetic acid (NAA), kinetin (KIN) and salicylic acid (SA), at concentrations of 0.1, 1, and 10 mg l -1 each]. Zygotic embryos were cultured on Murashige and Skoog (MS), and Gamborg media at different concentrations ( 1 / 1 , ½, and ¼ of its ionic strength) under conditions of darkness and photoperiod. Germination times of zygotic embryos cultured in MS medium had a mean of 5.1 days, whereas zygotic embryos cultured in B5 medium germinated with a mean of 7.5 days. Among the plant growth regulators used, gibberellic acid at 0.1 mg l -1 proved to be the most efficient in germinating zygotic embryos, with 100% germination reached by the 5th day. Germination time of zygotic embryos was 12 days when ABA at 0.1 mg l -1 was used; however, ABA inhibited germination of embryos when it was used at concentrations of 1.0 and 10 mg l -1 since only 10% germination occurred. Regarding the germination times of zygotic embryos of coffee, the priority order of efficiency was GA > KIN > SA > IBA > NAA > ABA. Also, with the exception of SA, concentrations higher than 0.1 mg l -1 increased the zygotic embryo germination rates. Key words : Zygotic embryos, coffee, germination, phytohormones.

GA3 induces expression of E2F-like genes and CDKA during in vitro germination of zygotic embryos of Cocos nucifera (L.)

Previous reports have demonstrated that gibberellins promote seed germination, including in vitro germination of zygotic embryos of coconut. Genes that control the cell cycle seem to play important roles during germination. In this study, complete full-length sequences of two E2F-like genes, CnE2F1 and CnE2F2, were obtained. Deduced amino acid sequences of both genes showed conserved domains characteristic of E2F genes. Both genes showed high homology with Arabidopsis thalianaE2Fa and E2Fb, which are transcriptional activators. The expression profiles of CnE2F genes were evaluated in in vitro zygotic embryos with or without gibberellic acid. In control embryos, expression of CnE2F1 showed a peak at day 2, and, gradually this dropped to similar levels as those at day 0. Gibberellic acid (GA3) treatment promoted expression at day 2, higher than that of the control. For CnE2F2, peak expression was detected at day 8 of culture. However, with GA treatment, CnE2F2 expression profile increased by day 2. The expression profile of a cyclin-dependent kinase (CnCDKA), another gene related to the cell cycle control, was also studied. In control embryos, expression of this gene showed two peaks at days 2 and 8, compared with day 0. A different profile was shown with GA treatment. In general, major changes in expression profiles were observed from days 2–8 when morphological changes in zygotic embryos were not yet observed.

Germinação de embriões zigóticos e desenvolvimento in vitro de coquinho-azedo

Este trabalho foi desenvolvido com objetivo de avaliar os efeitos da luz, das concentrações de sais MS e de sacarose sobre a germinação, in vitro, de embriões, e o desenvolvimento de plântulas de coquinho-azedo (Butia capitata (Mart.) Becc.). Para o preparo do meio de cultivo, foram utilizados sais MS suplementados com vitaminas, mio-inositol, caseína hidrolizada, carvão ativado, sacarose e ágar. Para avaliação do efeito da luminosidade, embriões zigóticos foram cultivados na presença e na ausência de luz. Diferentes concentrações de minerais MS (0; 25; 50; 75 e 100% em relação à formulação original do meio MS) foram testadas em associação com duas concentrações de sacarose ( de0 a 2%). Em ambos os experimentos, avaliaram-se, após 30 dias da inoculação, percentuais de oxidação, germinação e emissão de raízes e bainhas foliares. Os resultados obtidos mostraram que condição de luminosidade não afetou a germinação, porém, a ausência de luz favoreceu a emissão de raízes. Ocorreu o alongamento na ausência de sacarose, indicando a existência de reservas energéticas no embrião. A adição de sacarose proporcionou menores níveis de oxidação, favoreceu o alongamento e mostrou-se imprescindível para o desenvolvimento inicial das plântulas. Concentrações de sais entre 50 e 75% da concentração original do meio MS proporcionaram menores níveis de oxidação. A concentração de 75 % da concentração original de sais do meio MS proporcionou maior enraizamento.