In the growth condition(s) of plants, numerous secondary metabolites (SMs) are produced by them to serve variety of cellular functions essential for physiological processes, and recent increasing evidences have implicated stress and defense response signaling in their production. The type and concentration(s) of secondary molecule(s) produced by a plant are determined by the species, genotype, physiology, developmental stage and environmental factors during growth. This suggests the physiological adaptive responses employed by various plant taxonomic groups in coping with the stress and defensive stimuli. The past recent decades had witnessed renewed interest to study abiotic factors that influence secondary metabolism during in vitro and in vivo growth of plants. Application of molecular biology tools and techniques are facilitating understanding the signaling processes and pathways involved in the SMs production at subcellular, cellular, organ and whole plant systems during in vivo and in vitro growth, with application in metabolic engineering of biosynthetic pathways intermediates.

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Stress and defense responses in plant secondary metabolites production

Stevia rebaudiana (Asteraceae) is a plant of economic importance because of its medicinal properties and the presence of sweetener compounds on its leaves. These compounds can be a substitute for sucrose in a wide variety of products used by persons with diabetes and obesity problems. To standardize an efficient and effective propagation method for the different Stevia genotypes grown in Colombia, this study evaluated the effect of different combinations of the plant growth regulators 2,4-dichlorophenoxyacetic acid (2,4-D), indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), 6-(gamma, gamma-dimethylallylamino) purine (2iP) and Zeatin on the induction and development of somatic embryos. Adenine and coconut water were also evaluated as supplements in the basal culture medium Murashige and Skoog Basal Salt Mixture (MS) with glutamine. The combination of 2,4-D (18.09 µM) and 2iP (7.38 µM) produced the highest number of somatic embryos per explant, which had well-defined characteristics. The genotype showed a significant effect on the embryogenic response. In the "SRQ-93" genotype, the formation and development of somatic embryos was achieved, whereas the genotypes "Bertoni" and "Morita II" only yielded embryogenic and non-embryogenic calli, respectively. The conversion to seedlings was achieved on the regeneration medium containing gibberellic acid (GA 3 ) (0.29 µM) and activated charcoal.

EFFECT OF GENOTYPE ON THE in vitro REGENERATION OF Stevia rebaudiana VIA SOMATIC EMBRYOGENESIS Efecto del genotipo sobre la regeneración in vitro de Stevia rebaudiana a través de embriogénesis somática

. Hapsoro D, Hamiranti R, Yusnita Y. 2020. In vitro somatic embryogenesis of superior clones of robusta coffee from Lampung,Indonesia: Effect of genotypes and callus induction media. Biodiversitas 21: 3811-3817. This study aimed to investigate the effects of genotypes and primary callus induction media on somatic embryogenesis of superior robusta coffee clones of Lampung. Leaf explants of clones Tugusari, Komari, Tugino, and Wanto were cultured on two types of primary callus induction media (PCIM). PCIM1consisted of half-strength MS salts, 30 gL-1 sucrose, added with (mgL-1) 0.1 thiamine-HCl, 0.5 nicotinic acids, 0.5 pyridoxine-HCl, 100 Myo-inositol, 200 ascorbic acids, 150 citric acids, and 1 benzyl adenine. PCIM2 consisted of NPCM salts, 30 gL-1 sucrose, added with (mgL-1) 15 thiamine-HCl, 1 nicotinic acid, 1 pyridoxine-HCl, 2 glycines, 130 Myo-inositol, 200 ascorbic acids, 150 citric acids, 1 2,4- dichlorophenoxyacetic acid, and 2 thidiazuron. The highest percentage (100%) of primary callus formation was found in Komari and Wanto clones. PCIM2 resulted in more primary calli than PCIM1. When subcultured to embryogenic callus induction medium, primary calli of clone Komari and Wanto developed into a high percentage of embryogenic calli, while those of the other two turned brown and died. PCIM2-derived primary calli developed into more embryogenic calli. When subcultured on somatic embryo (SE) regeneration medium, these calli underwent the formation of SE of various stages. When subcultured to plant regeneration medium, these SEs developed into plantlets.
Keywords: 2.4 D, Coffea canephora, culture, regeneration, thidiazuron

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In vitro somatic embryogenesis of superior clones of robusta coffee from Lampung, Indonesia: Effect of genotypes and callus induction media

The clonal propagation of T. cacao by somatic embryogenesis (SE) is a promising approach to multiply elite genotypes. Assessing clonal fidelity in plants regenerated from somatic embryos is the fir...

https://www.tandfonline.com/doi/pdf/10.1080/15538362.2021.1873219

Determination of Genetic Stability in Cacao Plants (Theobroma Cacao L.) Derived from Somatic Embryogenesis Using Microsatellite Molecular Markers (SSR)

ABSTRACT One major problem with cacao crops is the variability of plantings obtained from seeds. This has led to considering somatic embryogenesis (SE), a means of obtaining stable clones with minimal somaclonal variation; however, achieving this has not been possible with many genotypes. In this work, we used IMC67 genotype (rootstock in the traditional grafting process) to evaluated various SE protocols; four culture media for induction and expression primary embryogenesis (PSE): induction medium (INDI), expression medium (INDIEXP), primary callus induction medium (PCG), and secondary callus growth medium (SCG), as well as two explants (petal and staminode). Different culture times for PSE (15, 25, 35, 45, 55, 65 days) and SSE (10, 20, 30, 40, 50, 70, 80 days) were evaluated in terms of callus formation, PSE, and SSE. For acclimation, seven substrates were evaluated for plantlet survival. One hundred percent callogenesis was achieved at 50 days with the staminode in INDI, and the most PSE per explant (8) in INDIexp was achieved at 45 days. Secondary somatic embryogenesis (SSE) obtained the most globular and cotyledonary embryos (30) at 30 days in callus multiplication (CM2). The embryos achieved conversion and development into plantlets in maturation medium (MM6). Embryogenic efficiency from explants was 11.7 for PSE, and 15.2 for SSE. Acclimation obtained a 42.1% survival rate in the 70% sand- 30% soil substrate. This work reports a complete regeneration protocol via somatic embryogenesis up to plantlet development in a nursey for the IMC67 rootstock genotype; contributing to standardizing a high-quality plant production system.

https://www.tandfonline.com/doi/pdf/10.1080/15538362.2021.2023067?needAccess=true

Propagation of IMC67 Plants, Universal Cacao (Theobroma Cacao L.) Rootstock via Somatic Embryogenesis

In this research we evaluate two protocols of propagation via somatic embryogenesis from floral explants using two elite clones BIOB and ICS95 of Theobroma cacao L. We obtained 50 and 32% of embryogenic callus on ICS95 and BIOB respectively with Fontanel et al., (2002) modified protocol and Guiltinan et al. (2003) after three months of culture. The embryos went through four phases; Induction, Formation, Maduration and Mantenimiento which corresponded each one with different media culture. For secondary somatic embryogenesis we obtained 23% of embryos from primary somatic embryos in a medium with 1mg/L of 2,4,5 T (2,4,5 Triclorofenoxiacetic). Also we obtained plants that developed new roots applying pulses with IBA (Indol Butiric Acid) 0.5mg/L and 0.5g/L for a minute. The developed plants were moved to a mix of potting soil and sand (1:1) for their ex vitro adaptation, getting 66% of acclimatized plants. The histological analysis showed the typical characteristics of the embryogenic development. This is the first report where it is achieved the successful conversion to plantlets (68%) and ex vitro adaptation of a colombian cocoa variety via primary and secondary embryogenesis.

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Regeneration through somatic embryogenesis of an elite colombian Theobroma cacao L. variety

In spite of its pharmacological, nutritional and industrial properties and its great potential market, Curcuma longa L. has not been commercialized to the extent that would be expected. The difficulty of propagation of the species, which is provided exclusively by vegetative to be a sterile triploid, coupled with the environmental requirements of the crop and its high susceptibility to attack by different pathogens, have been the causes for which has not been given a use according to the properties and potential of the plant. As a strategy for obtaining large numbers of germplasm with optimal phytosanitary characteristics, different techniques have been implemented in vitro culture, including the formation of microrrizomas and micropropagation of plants. However, not yet available efficient methods for somatic embryogenesis and organogenesis induction processes. In this study, we report the effect of different plant growth regulators and their combinations on the leaf segments, leaf bases and thin cells layers (TCL) of Curcuma longa L. for the callus and embryos induction. The evaluated tissues showed a differential response, according to its characteristics and the plant growth regulators added. Embryogenic response was particularly obtained in leaf bases and TCL. On the other hand, it was possible to induce cauline and root morphogenesis simultaneously in all evaluated tissue. Regenerated plants from leaf bases were more vigorous than the others tissues.

https://dialnet.unirioja.es/descarga/articulo/4997033.pdf

Organogénesis y embriogénesis en Curcuma longa L. a partir de capas delgadas de células, segmentos y bases de hoja Curcuma longa L. embryogenesis and organogenesis from thin cell layers, leaf segments and bases of leaf

Knowing the medicinal properties of the plant specie Psychotria ipecacuanha (Brot.) Stokes, its critical condition and the difficulties for its effective propagation, the present study aimed to assess the potential of propagation of P. ipecacuanha by in vitro systems of regeneration, organogenesis and somatic embryogenesis. For this purpose, thin cell layers (TCL) of stems and leaves, as well as leaf segments were subjected to different treatments of plant growth regulators and light conditions. Furthermore, the effect of different wavelengths via light emitting diodes (LED’s), was established for the regeneration in these explants and nodal explants from in vitro plants. The results showed that leaf segments and stem TCL, cultured in MS medium supplemented with the combinations of growth regulators IBA + BAP and IBA + TDZ, formed somatic embryos and shoots. The histological sections supported the two types of source. It was found that the best results in shoot induction and embryos were achieved under the light condition 16/8-h light/ dark. Regarding the effect of different wavelengths, it was found that those corresponding to red, green, and white supported the growth and shoot development as well as somatic embryos induction. The shoots development from the nodal explants did not show statistical differences between LEDs treatments, so the use of a continuous white light and photoperiod is recommended during their multiplication and development.

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POTENCIAL DE REGENERACIÓN DE Psychotria ipecacuanha (Rubiaceae) A PARTIR DE CAPAS DELGADAS DE CÉLULAS Regeneration Potential of Psychotria ipecacuanha (Rubiaceae) from Thin Cell Layers

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Papers

EFFECT OF GENOTYPE ON THE in vitro REGENERATION OF Stevia rebaudiana VIA SOMATIC EMBRYOGENESIS Efecto del genotipo sobre la regeneración in vitro de Stevia rebaudiana a través de embriogénesis somática

Regeneration through somatic embryogenesis of an elite colombian Theobroma cacao L. variety

Organogénesis y embriogénesis en Curcuma longa L. a partir de capas delgadas de células, segmentos y bases de hoja Curcuma longa L. embryogenesis and organogenesis from thin cell layers, leaf segments and bases of leaf

POTENCIAL DE REGENERACIÓN DE Psychotria ipecacuanha (Rubiaceae) A PARTIR DE CAPAS DELGADAS DE CÉLULAS Regeneration Potential of Psychotria ipecacuanha (Rubiaceae) from Thin Cell Layers