Somatic Embryo Induction Medium Research Articles

Impact of activated charcoal on the progression of somatic embryogenesis in grape cells: Histological and transcriptomic perspectives

Somatic embryogenesis is a crucial genetic transformation method in plants. Despite numerous studies being conducted for acquiring embryogenic competence in plant cells, somatic embryo (SE) induction from embryogenic cells (ECs) has attracted relatively limited research attention. In grapes, somatic cell induction is impeded by unidentified inhibitors, which hinders the progression of globular embryo (GE) formation and subsequently embryo development. We found that addition of activated charcoal (AC) to the grape SE induction medium augmented the speed, consistency, and synchronization of embryogenesis. Cell samples cultured in the induction medium with and without AC were thoroughly evaluated through histological anatomy analysis, subcellular structure observation, and comparative transcriptomic analysis. The histological observation revealed the specific timeline of SE formation. An intermediate developmental state, referred to as the globular embryo precursor (PGE), was observed during the induction of GE formation from EC. Members of transcription factor families such as WRKY, MYB, MADS, AP2/ERF, HB-KNOX, HB-HD-ZIP, HB-WOX, NAC, and GRF were identified in the early and middle stages of GE formation. Additionally, we explored the key roles of reactive oxygen species (ROS)-, starch-, cell wall-, and hormone-related genes. The cell wall-related genes were highly enriched in differentially expressed gene sets. Several amyloplasts in EC disappeared, potentially because of hydrolysis, and numerous mitochondria were observed. In AC-added samples, starch was consumed more, and cellulose hydrolysis-related genes were downregulated, whereas cellulose synthesis-related genes had higher expression than AC-free samples. ROS response-related genes were induced when GE induction was initiated. When applied, an optimal concentration of external H2O2 promoted SE initiation in grapes, whereas a high concentration caused delayed GE formation. This study suggests that, by absorbing and releasing substances, the added AC can create a stable buffer environment for cell survival, protect against excessive ROS- or inhibitor-induced cell damage, and support uninterrupted progress of somatic embryogenesis.

EFFECT OF 2,4-D AND NAA ON SOMATIC EMBRYOGENESIS FROM APICAL PORTION OF GROUNDNUT (ARACHIS HYPOGAEA L.)

Somatic embryogenesis was carried out epicotyl portion of the mature embryo/apical portion. The somatic embryo induction medium containing 2,4-D or NAA (10.0 to 50.0 mg/l). Of the two concentrations tested 2,4-D (30.0mg/l) recorded the highest percentage of response followed by NAA (30.0mg/l). But the highest number of somatic embryo were recorded in 30.0mg/l of 2,4-D followed by NAA. The apical portion of the mature embryo formed direct embryos without any intervention of callus. The maximum percentage of embryogenic cultures were noticed in 30.0mg/l of 2,4-D followed by NAA at 30.0mg/l. for the differentiation of somatic embryos, the embryogenic masses were transferred to medium without any growth regulator. The maximum number of somatic embryos per culture was recorded in 30 mg/l of 2,4-D followed by 30.0 mg/l of NAA. Keywords: Arachis hypogaea L.,Somatic Embryogenesis, 2,4-D and NAA

Enhancement of heavy metal tolerance and accumulation efficiency by expressing Arabidopsis ATP sulfurylase gene in alfalfa

Transgenic alfalfa (Medicago sativa L.) plants overexpressing the Arabidopsis ATP sulfurylase gene were generated using Agrobacterium-mediated genetic transformation to enhance their heavy metal accumulation efficiency. The ATP sulfurylase gene was cloned from Arabidopsis, following exposure to vanadium (V) and lead (Pb), and transferred into an Agrobacterium tumefaciens binary vector. This was co-cultivated with leaf explants of the alfalfa genotype Regen SY. Co-cultivated leaf explants were cultured on callus and somatic embryo induction medium, followed by regeneration medium for regenerating complete transgenic plants. The transgenic nature of the plants was confirmed using PCR and southern hybridization. The expression of Arabidopsis ATP sulfurylase gene in the transgenic plants was evaluated through RT-PCR. The selected transgenic lines showed increased tolerance to a mixture of five heavy metals and also demonstrated enhanced metal uptake ability under controlled conditions. The transgenic lines were fertile and did not exhibit any apparent morphological abnormality. The results of this study indicated an effective approach to improve the heavy metal accumulation ability of alfalfa plants which can then be used for the remediation of contaminated soil in arid regions.

Induksi dan Proliferasi Embriogenesis Somatik In Vitro pada Lima Genotipe Kedelai

ABSTRACT<br /><br />Somatic embryo induction medium was reported to be genotype dependent for soybean. This study was aimed to obtain the optimum medium for embryo somatic induction and proliferation, and to regenerate somatic embryo of five soybean genotypes. Five soybean genotypes (Tanggamus, Anjasmoro, Yellow Biloxi, CG-22-10, and SP-10-4) were used in this study. The research was divided into four steps: (1) embryogenic callus induction of five soybean genotypes, (2) embryogenic callus proliferation of five soybean genotypes, (3) optimation of embryo somatic induction on five soybean genotypes and (4) embryo somatic regeneration of five soybean genotypes. The induction experiment showed that based on number of embryogenic callus, the best somatic embryo-induction medium was 3% sucrose+ NAA 5 mg L-1+2,4-D 5 mg L-1+ Vitamin B5. Embryogenic callus number for each genotype tested was increased on proliferation media of 3% sukrosa + 2,4-D 5 mg L-1 + NAA 5 mg L-1+ Vit B5, and Yellow Biloxi gave the highest number of proliferated somatic embryos compared to other genotypes. Increasing number of globular somatic embryo of all genotypes was obtained from the optimation of somatic embryo induction media being used, and Tanggamus genotype gave the highest number of globular somatic embryo which followed by Yellow Biloxi genotype. Tanggamus and Yellow Biloxi genotypes were also successfully formed the four steps of somatic embryos (globular, heart, torpedo, and cotyledonary stages), but in regeneration medium of MS0 and media MS + sukrosa 10 g L-1 + GA3 2 mg L-1 + BAP 4 mg L-1 + Vit B5 only Tanggamus genotype was regenerated into plantlet. <br /><br />Keywords: 2,4-D, NAA, somatic embryos, induction, proliferation<br /><br />

An efficient protocol for transferring selectable marker gene gus/gusplus into cassava plants (Manihot esculenta Crantz) mediated by bacteria Agrobacterium tumefaciens

In this study, to evaluate the ability to accept transgenes of the two cassava cultivars KM94 and KM140, which are grown widely in Viet Nam, A. tumefaciens bacterial strains C58/pGV2260, EHA105 and LBA4404 containing vector pCB-gusplus or pPIPRA558 haboring selectable marker gene gus/gusplus, were co-inoculated with explants from four selected sources, including (1) immature leaves, (2) shoot apexes, (3) callus, and (4) somatic embryo cotyledons. Transgenic explants were selected using three antibiotics kanamycin, neomycin, and paromomycin, at concentrations of 25, 50, 75, and 100 mg/l , based on nptII gene. These experiments were conducted to optimize conditions for transferring gus gene to cassava plant. The transformation efficiency was evaluated based on the percentage of X-gluc positive stained explants 10 days after infection, somatic embryos, regenerated shoots and whole regenerated plants. The highest transformation efficiency was achieved when using A. tumefaciens C58/pGV2260, carrying expression vector pCB-gusplus, and cotyledons of cultivars KM94. In this protocol, cotyledons were cut into small pieces, then cultured on the callus induction medium for 2 days and submerged in bacterial suspension, supplemented with 100 μM AS, with shaking at 50 rpm for 15 minutes. Explants were then co-cultured on somatic embryo induction medium supplemented with 150 μM AS in the darkness for 2 days. Explants were then transferred to selective callus induction medium with 50 mg/l kanamycin for 3 - 4 weeks, followed by the culture on selective shoot induction medium with the same kanamycin concentration. Shoots, with 2 - 3 leaves, were transferred to a selective rooting medium to establish whole plants.

Plantlet Regeneration of Somatic embryos from Leaf Explants of Mentha arvensis(L.) A medicinally important Plant

The present study was conducted with the aim of evaluating some of the factors that influence induction and plantlet regeneration of somatic embryos in Mentha arvensis ( L) var piperascens Holmes (menthol or Japanese mint)since there are no available reports on Somatic embryogenesis and regeneration of plantlet in this medicinally important plant species. Leaves from plants growing under temporary shed were cultured on Murashige and Skoog medium fortified with (0.5-5.0mg/L) Napthlene acetic acid (NAA)+(0.5 mg/L)Thidizuron(TDZ). High frequency of somatic embryo formation was found at (2.5mg/L) NAA+ (0.5mg/L) TDZ in leaf explants respectively, Secondary somatic embryogenesis was also observed when primary somatic embryos were sub cultured same somatic embryo induction medium well developed cotyledonary stage embryos were germinated on MS medium supplemented with (0.5mg/L) (NAA) + (0.5-5.0mg/L)TDZ maximum 80% of somatic embryos germination and plant let formation was found at (2.5 mg/L) NAA+ (0.5 mg/L) (TDZ). The post translation survival rate of plants was 80% plants and flowers formation were morphological similar to the mother plants.

Performance of peanut mutants and their offspring generated from mixed high-energy particle field radiation and tissue culture

To develop new ways to breed peanut, we irradiated seeds of the Luhua 11 cultivar with a mixed high-energy particle field at different doses. The embryonic leaflets were extracted as explants and incubated on somatic embryo induction medium and then on somatic embryo germination and regeneration medium. After being grafted, the M1-generation plants were transplanted, and seeds from each M1-generation plant were harvested. In the following year, the M2-generation seeds were planted separately. Some M2-generation plants showed distinct character segregation relative to the mutagenic parent in terms of vigor, fertility, plant height, branch number, and pod size and shape. M2-generation plants that had a high pod weight per plant tended to produce M3-generation offspring that also had a high pod weight per plant, much higher than that of the mutagenic parent, Luhua 11. M4-generation seeds varied greatly in quality, and 35 individuals with an increased fat content (>55%) were obtained. Overall, the results indicate that the combination of mutagenesis via mixed high-energy particle field exposure and tissue culture is promising for peanut breeding.

English

An attempt was made to study the somatic embryogenesis and plant regeneration from the in vitro leaf explants of Rumex vesicarius L. a renowned medicinal plant, which belongs to polygonaceae family. Effective in vitro regeneration of R. vesicarius was achieved via young leaf derived somatic embryo cultures. Embryogenic callus was induced from leaf explants on Schenk and Hildebrandt (SH) medium supplemented with various concentrations of 2,4-dichlorophenoxy acetic acid (2,4-D) (0.5 to 3.0 mg/l) along with Kinetin (Kn) (0.5 mg/l). High frequency of somatic embryogenesis was effective on SH medium with 2, 4-D (2.5 mg/l) + Kn (0.5 mg/l) from leaf explants. Secondary somatic embryogenesis was also observed when primary somatic embryos were subculture on the same somatic embryo induction medium. Well developed cotyledonary shaped embryos regenerate 80% of shoots on media containing 2,4-D 0.5 mg/l + 2.0 mg/l BA. The regenerated shoots transferred to rooting media containing Indole- 3- butyric acid (IBA). Efficient rooting of 90% was noted on SH media with 1.0 mg/l IBA. Finally, these in vitro regenerated plantlets were hardened, acclimatized and successfully transferred to the field. The post transplantation survival rate of these regenerated plants was 65 to 70%. The in vitro regenerated plants and flowers were similar to mother plants. This protocol will be useful for genetic transformation experiments in R. vesicarius L. Keywords: Rumex vesicarius L, 2,4-dichlorophenoxy acetic acid (2,4-D), kinetin (Kn), Benzyl adenine (BA), Indole- 3- butyric acid (IBA). African Journal of Biotechnology , Vol 13(45) 4268-4274

Vacuum infiltration enhances the Agrobacterium-mediated genetic transformation in Indian soybean cultivars

For the first time we have developed a reliable and efficient vacuum infiltration-assisted Agrobacterium-mediated genetic transformation (VIAAT) protocol for Indian soybean cultivars and recovered fertile transgenic soybean plants through somatic embryogenesis. Immature cotyledons were used as an explant and three Agrobacterium tumefaciens strains (EHA 101, EHA 105, and KYRT 1) harbouring the binary vector pCAMBIA1301 were experimented in the co-cultivation. The immature cotyledons were pre-cultured in liquid somatic embryo induction medium prior to vacuum infiltration with the Agrobacterium suspension and co-cultivated for 3 days on co-cultivation medium containing 50 mg l−1 citric acid, 100 µM acetosyringone, and 100 mg l−1 l-cysteine. The transformed somatic embryos were selected in liquid somatic embryo induction medium containing 10 mg l−1 hygromycin and the embryos were germinated in basal medium containing 20 mg l−1 hygromycin. The presence and integration of the hpt II and gus genes into the soybean genome were confirmed by GUS histochemical assay, polymerase chain reaction, and Southern hybridization. Among the different combinations tested, high transformation efficiency (9.45 %) was achieved when immature cotyledons of cv. Pusa 16 were pre-cultured for 18 h and vacuum infiltrated with Agrobacterium tumefaciens KYRT 1 for 2 min at 750 mm of Hg. Among six Indian soybean cultivars tested, Pusa 16 showed highest transformation efficiency of 9.45 %. The transformation efficiency of this method (VIAAT) was higher than previously reported sonication-assisted Agrobacterium-mediated transformation. These results suggest that an efficient Agrobacterium-mediated transformation protocol for stable integration of foreign genes into soybean has been developed.

Effect of growth regulators on microspore embryogenesis in coconut anthers

The effect of growth regulators on induction of androgenesis in coconut was investigated using seven different growth regulators at various concentrations and combinations. Three auxins (1-naphthalene acetic acid—NAA, indoleacetic acid—IAA, picloram) and three cytokinins (2-isopentyl adenine-2-iP, kinetin, zeatin) were tested either alone or in combination with 2,4-dichlorophenoxyacetic acid (2,4-D), using modified Eeuwens Y3 liquid medium as the basal medium. Among the tested auxins, 100 μM NAA in combination with 100 μM 2,4-D enhanced the production of calli/embryos (123) whereas IAA and picloram showed negative and detrimental effects, respectively, for androgenesis induction over 100 μM 2,4-D alone. Kinetin and 2-iP enhanced the production of calli/embryos when 100 μM 2,4-D was present in the culture medium. Both cytokinins at 10 μM yielded the highest frequencies of embryos (113 and 93, respectively) whereas zeatin (1 or 2.5 μM) had no impact on microspore embryogenesis. When calli/embryos (produced from different treatments in different experiments) were sub-cultured in somatic embryo induction medium (Y3 medium containing 66 μM 2,4-D), followed by maturation medium (Y3 medium without growth regulators) and germination medium (Y3 medium containing 5 μM-6-benzyladenine—BA and 0.35 μM gibberellic acid—GA3), plantlets were regenerated at low frequencies (in most treatments ranging from 0% to 7%).

High frequency plant regeneration from protoplasts in cotton via somatic embryogenesis

A highly reproducible system for efficient plant regeneration from protoplast via somatic embryogenesis was developed in cotton (Gossypium hirsutum L.) cultivar ZDM-3. Embryogenic callus, somatic embryos and suspension culture cells were used as explants. Callus-forming frequency (82.86 %) was obtained in protoplast cultures from suspension culture cells in KM8P medium with 0.45 µM 2,4-dichlorophenoxyacetic acid (2,4-D), 0.93 µM kinetin (KIN), 1.5 % glucose and 1.5 % maltose. Protocolonies formed in two months with plating efficiency of 14 %. However, the callus-forming efficiencies from other two explants were low. The calli from protoplast culture were transferred to somatic embryo induction medium and 12.7 % of normal plantlets were obtained on medium contained 3 % maltose or 1 % of each sucrose + maltose + glucose, 2.46 µM indole-3-butyric acid (IBA) and 0.93 µM KIN. Over 100 plantlets were obtained from protoplasts derived from three explants. The regenerated plants were transferred to the soil and the highest survival rate (95 %) was observed in transplanting via a new method.

EMBRIOGENESIS SOMATIK ANGGREK BULAN Phalaenopsis amabilis (L.) Bl: STRUKTUR DAN POLA PERKEMBANGAN

Research of the structure and development pattern of somatic embryos from callus of leaf explants moon orchid Phalaenopsis amabilis (L) Bl had been done. One year old of plantlets were used as explants sources. Basal leaf of these explants were cultured in Somatic Embryo Induction Medium (SEIM) e.i.: NP(New Phalaenopsis) medium added with 2 mg/L NAA, 1 mg/L BA, 10 g/L sucrose, and 2 g/L gellan gum. Then somatic embryos were transferred to EMM (Embryo Maturation Medium) e.i. NP medium added with 1 mg/L NAA, 1 mg/L BA, 10 g/L sucrose, and 2 g/L gellan gum. Finally, mature somatic embryo were transferred to NP medium without plant growth regulator as Embryo Germination Medium (EGM). The origin of somatic embryos initially from single cell at the pheriphery of embryogenic callus. These cells then devided in mitotic repeatedly formed globular proembryo, elongation embryo, and completed embryo. The structure and development pattern of somatic embryos as the same as with zygotic embryo.

Somatic Embryogenesis and Plant Development in Centella asiatica L., a Highly Prized Medicinal Plant of the Tropics

Past research experience with Centella asiatica micropropagation suggests a very high rate of contamination during the culture establishment stage. We demonstrate protocols for successful sterilization of Centella explants prepared from field-grown plants with an abundance of fungal and bacterial contamination. Sequential steps during sterilization and explant preparation process included a dip for 30 s in 70% ethyl alcohol, weak bleach treatment for 12 min, and a 60-min soak in plant preservative mixture before establishing cultures. We also report a reproducible system for somatic embryogenesis in Centella using leaf and stolon tip explants collected from naturally growing populations. Somatic embryos were induced within 3 to 4 weeks of culture in the dark on Murashige and Skoog (MS) medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D). Initial embryogenic mass appeared as nodular callus, which eventually developed into actual somatic embryos exhibiting globular, heart-shaped, and cotyledonary stages. Leaves produced embryogenic calli at 2.26 and 4.52 μm 2,4-D, whereas stolon tips were responsive only in the 9.04 μm 2,4-D treatment. Withdrawal of 2,4-D/growth regulators from the induction medium resulted in the maturation and further development of the embryos into plantlets. Regular subculturing of the embryogenic calli into MS medium sustained their regenarability for more than 1 year. Somatic embryos were individually encapsulated in sodium alginate and calcium chloride-based encapsulation matrix to produce artificial or synthetic seeds (synseeds). Synseeds with 2% sodium alginate were found best for the survival and germination recorded after their storage at 5 to 8 °C for 30 and 60 days. We report protocols for C. asiatica to reduce explant contamination before establishment of cultures on somatic embryo induction medium and efficient somatic embryogenesis to facilitate conservation and mass production of elite germplasm. This may further assist rapid dissemination of superior clones needed for research and commercial production.

Somatic embryogenesis of two indigenous South African Haworthia spp. (H. limifolia and H. koelmaniorum)

The endangered, indigenous succulents, Haworthia koelmaniorum and H . limifolia , have been micropropagated using somatic embryogenesis. The somatic embryo induction medium contained MS macro- and micro-nutrients (MS), 20 g I − 1 sucrose and 10 g I − 1 agar, pH 5.6. For H . limifolia the following plant growth regulators were tested: 2,4-D (1, 2 and 5 mg I − 1 ), picloram (1 and 2 mg I − 1 ) and 0.25 mg I − 1 kinetin plus 1 or 2 mg I − 1 picloram. Direct somatic embryogenesis occurred best from explants (apical one third of leaf) exposed to 2 mg I − 1 2,4 D. However, when the embryoids were transferred to plant growth-regulator-free medium they did not germinate but rather de-differentiated to callus and then underwent secondary embryogenesis. Hyperhydricity of the secondary embryoids was obviated by culturing in the presence of silica gel, and material treated in this manner differentiated into plantlets, which could be hardened. For H . koelmaniorum 2 mg I − 1 picloram and 0.25 mg I − 1 kinetin were also added to the embryo induction medium and the effect of ABA on embryoid induction was tested at 0.1, 0,2 and 0.3 mg I − 1 . Somatic embryoids, which could be germinated and hardened, developed directly from somatic cells of the leaf explant when the tissues were exposed to either 0,2 or 0.3 mg I − 1 ABA.

Role of purine metabolism in thidiazuron‐induced somatic embryogenesis of geranium (Pelargonium×hortorum) hypocotyl cultures

Somatic embryogenesis in geranium (Pelargonium×hortorum Bailey cv. Scarlet Orbit Improved) was achieved by culturing hypocotyl sections on Murashige and Skoog (1962) (MS) medium containing 10 μM thidiazuron (TDZ) (induction medium) for 3 days and subsequently transferring the sections onto a basal medium lacking any plant growth regulators (expression medium). Addition of the purine analogue 2.6‐diaminopurine (DAP) to the somatic embryo induction medium completely inhibited the embryogenic response as well as chlorophyll accumulation without affecting enlargement of the treated tissues. Addition of 20 μM adenine sulphate to the expression medium, i.e during embryo growth and development phase, completely reversed the DAP‐induced inhibition of the embryogenic response while addition during the induction phase caused only a 50% reversal of the inhibition. Analysis of endogenous levels of plant growth substances indicated that TDZ alone elevated the levels of auxins, cy‐tokinins and abscisic acid while the presence of DAP during the induction phase caused a further increase in the levels of adenine and adenosine. These findings indicate a possible critical role for purines in embryogenesis from geranium hypocotyl tissues. However, the conversion of cytokinin bases to their corresponding nucleotide forms was not evident as the levels of isopentenyl adenine and zeatin increased during the second day of culture.