Different Roles of Auxins in Somatic Embryogenesis Efficiency in Two Picea Species

Modulating ascorbic acid levels to optimize somatic embryogenesis in Picea abies (L.) H. Karst. Insights into oxidative stress and endogenous phytohormones regulation

Global warming has adversely affected Picea abies (L.) H. Karst. forests in Europe, prompting the need for innovative forest-breeding strategies. Somatic embryogenesis (SE) offers promise but requires protocol refinement. Understanding the molecular mechanisms governing somatic embryo development is essential, as oxidative stress plays a crucial role in SE regulation. Ascorbic acid (ASA), is a vital antioxidant that can potentially control oxidative stress. In the present study, we normalized ASA concentrations in induction and proliferation media to enhance embryogenic tissue (ET) regeneration and proliferation capacity of mature explants. The media were supplemented with ASA at 0 mg l-1, 25 mg l-1, 50 mg l-1, 100 mg l-1, and 200 mg l-1. The accumulation of hydrogen peroxide (H2O2) and endogenous phytohormones, including auxins, cytokinins, brassinosteroids, abscisic acid, and gibberellin, was measured in non-embryonic calli and ET. Subsequently, their impact on ET induction and multiplication was analyzed. Our results demonstrate that application of ASA at concentrations of 25 mg l-1 and 200 mg l-1 led to increased H2O2 levels, potentially inducing oxidative stress while simultaneously reducing the levels of all endohormone groups. Notably, the highest ET induction frequency (approximately 70%) was observed for ASA at 50 mg l-1. These findings will enhance SE induction procedures, particularly in more resistant explants, underscoring the significance of ASA application to culture media.

Enhancing in vitro regeneration via somatic embryogenesis and Fusarium wilt resistance of Egyptian cucumber (Cucumis sativus L.) cultivars

BACKGROUND

Somatic embryogenesis offers a reliable method for cucumber (Cucumis sativus L.) regeneration and genetic enhancement against Fusarium wilt. This study aimed to establish a tailored somatic embryogenesis system for Egyptian cultivars, fostering genetic improvements and Fusarium wilt-resistance lines.

RESULTS

Employing the Optimal Arbitrary Design (OAD) approach, we optimized the induction medium, initiating prolific embryogenic calli (53.3 %) at 1 mg/L 2,4-D. The cotyledonary leaf (CL) was the preferred explant, showing 60 % embryogenic callus development. Bieth Alpha exhibited higher responsiveness, generating ∼ 18 somatic embryos per explant compared to Prince's ∼ 10. Somatic embryogenesis system validation used quantitative RT-PCR, showing Cucumis sativus splicing factor 3B subunit (CUS1) and an embryogenesis marker gene expression exclusively within embryogenic calli and mainly during embryogenesis initiation. Evaluating fungal toxin filtrate concentrations for selecting embryogenic calli, the S2 selection (25 % filtrate, four subculture cycles) was chosen for somatic embryo development. To gauge the ramifications of selection at the genetic stratum, an in-depth analysis was executed. A cluster analysis grounded in ISSR banding patterns revealed a distinct separation between in vivo-cultivated plants of the two cultivars and regenerated plants devoid of pathogen filtrate treatment or those regenerated post-filtrate treatment. This segregation distinctly underscores the discernible genetic impact of the selection process.

CONCLUSIONS

The highest embryogenic capacity (53.3%) was achieved in this study by optimizing the induction stage, which demonstrated the optimal concentrations of BA and 2,4-D for induced proembryonic masses. Moreover, consistent gene expression throughout both stages of embryogenesis suggests that our system unequivocally follows the somatic embryogenesis pathway.

Advancing Antibiotic Residue Analysis: LC-MS/MS Methodology for Ticarcillin Degradation Products in Tomato Leaves

The indiscriminate use of antibiotics in agriculture has raised concerns about antibiotic residues in food products, necessitating robust analytical methods for detection and quantification. In this study, our primary aim was to develop a robust and advanced liquid chromatography-tandem mass spectrometry (LC-MS/MS) methodology specifically designed for the accurate quantification of ticarcillin degradation products in tomato leaves. The choice of ticarcillin as the target analyte stems from its frequent use in agriculture and the potential formation of degradation products, which can pose a threat to food safety. The use of tomatoes as the target sample matrix in this study is justified by their significance in human diets, their widespread cultivation, and their suitability as a model for assessing antibiotic residue dynamics in diverse agricultural environments. By optimizing the MS/MS parameters, the study successfully demonstrates the practicality and reliability of the employed LC-MS/MS method in accurately assessing ticarcillin degradation product (Thiophene-2-Acetic acid and Thiophene-3-Acetic acid) levels. The chromatographic separation was achieved using a specialized column, ensuring high resolution and sensitivity in detecting analytes. Multiple reaction monitoring (MRM) data acquisition was employed to enhance the selectivity and accuracy of the analysis. The developed method exhibited excellent linearity and precision, meeting the stringent requirements for antibiotic residue analysis in complex matrices. Key outcomes of this study include the successful identification and quantification of ticarcillin and its degradation products in tomato leaves, providing crucial insights into the fate of this antibiotic in agricultural settings. The methodology's applicability was further demonstrated by analyzing real-world samples, highlighting its potential for routine monitoring and ensuring food safety compliance. In summary, our study constitutes a noteworthy advancement in the domain of antibiotic residue analysis, offering a reliable method for quantifying ticarcillin degradation products in tomato leaves. The optimized parameters and MRM-based LC-MS/MS approach enhance the precision and sensitivity of the analysis, opening up opportunities for further studies in the assessment of antibiotic residues in agricultural ecosystems.

Fungal Elicitation Enhances Vincristine and Vinblastine Yield in the Embryogenic Tissues of Catharanthus roseus

Fungal elicitation could improve the secondary metabolite contents of in vitro cultures. Herein, we report the effect of Fusarium oxysporum on vinblastine and vincristine alkaloid yields in Catharanthus roseus embryos. The study revealed increased yields of vinblastine and vincristine in Catharanthus tissues. Different concentrations, i.e., 0.05% (T1), 0.15% (T2), 0.25% (T3), and 0.35% (T4), of an F. oxysporum extract were applied to a solid MS medium in addition to a control (T0). Embryogenic calli were formed from the hypocotyl explants of germinating seedlings, and the tissues were exposed to Fusarium extract elicitation. The administration of the F. oxysporum extract improved the growth of the callus biomass, which later differentiated into embryos, and the maximum induction of somatic embryos was noted T2 concentration (102.69/callus mass). A biochemical analysis revealed extra accumulations of sugar, protein, and proline in the fungus-elicitated cultivating tissues. The somatic embryos germinated into plantlets on full-strength MS medium supplemented with 2.24 µM of BA. The germination rate of the embryos and the shoot and root lengths of the embryos were high at low doses of the Fusarium treatment. The yields of vinblastine and vincristine were measured in different treated tissues via high-pressure thin-layer chromatography (HPTLC). The yield of vinblastine was high in mature (45-day old) embryos (1.229 µg g-1 dry weight), which were further enriched (1.267 µg g-1 dry weight) via the F. oxysporum-elicitated treatment, especially at the T2 concentration. Compared to vinblastine, the vincristine content was low, with a maximum of 0.307 µg g-1 dry weight following the addition of the F. oxysporum treatment. The highest and increased yields of vinblastine and vincristine, 7.88 and 15.50%, were noted in F. oxysporum-amended tissues. The maturated and germinating somatic embryos had high levels of SOD activity, and upon the addition of the fungal extracts, the enzyme's activity was further elevated, indicating that the tissues experienced cellular stress which yielded increased levels of vinblastine and vincristine following the T2/T1 treatments. The improvement in the yields of these alkaloids could augment cancer healthcare treatments, making them easy, accessible, and inexpensive.

Efficient Plant Regeneration System from Leaf Explant Cultures of Daphne genkwa via Somatic Embryogenesis

This study aimed to establish an efficient plant regeneration system from leaf-derived embryogenic structure cultures of Daphne genkwa. To induce embryogenic structures, fully expanded leaf explants of D. genkwa were cultured on Murashige and Skoog (MS) medium supplemented with 0, 0.1, 0.5, 1, 2, and 5 mg·L^-1 2,4-dichlorophenoxyacetic acid (2,4-D), respectively. After 8 weeks of incubation, the highest frequency of embryogenic structure formation reached 100% when the leaf explants were cultivated on MS medium supplemented with 0.1 to 1 mg·L^-1 2,4-D. At higher concentrations of 2,4-D (over 2 mg·L^-1 2,4-D), the frequency of embryogenic structure formation significantly declined. Similar to 2,4-D, indole butyric acid (IBA) and α-naphthaleneacetic acid (NAA) treatments were also able to form embryogenic structures. However, the frequency of embryogenic structure formation was lower than that of 2,4-D. In particular, the yellow embryonic structure (YES) and white embryonic structure (WES) were simultaneously developed from the leaf explants of D. genkwa on culture medium containing 2,4-D, IBA, and NAA, respectively. Embryogenic calluses (ECs) were formed from the YES after subsequent rounds of subculture on MS medium supplemented with 1 mg·L^-1 2,4-D. To regenerate whole plants, the embryogenic callus (EC) and the two embryogenic structures (YES and WES) were transferred onto MS medium supplemented with 0.1 mg·L^-1 6-benzyl aminopurine (BA). The YES had the highest plant regeneration potential via somatic embryo and shoot development compared to the EC and WES. To our knowledge, this is the first successful report of a plant regeneration system via the somatic embryogenesis of D. genkwa. Thus, the embryogenic structures and plant regeneration system of D. genkwa could be applied to mass proliferation and genetic modification for pharmaceutical metabolite production in D. genkwa.

Conifer Biotechnology: An Overview

The peculiar characteristics of conifers determine the difficulty of their study and their great importance from various points of view. However, their study faces numerous important scientific, methodological, cultural, economic, social, and legal challenges. This paper presents an approach to several of those challenges and proposes a multidisciplinary scientific perspective that leads to a holistic understanding of conifers from the perspective of the latest technical, computer, and scientific advances. This review highlights the deep connection that all scientific contributions to conifers can have in each other as fully interrelated communicating vessels.

Induction of Somatic Embryogenesis in Tamarillo (Solanum betaceum Cav.) Involves Increases in the Endogenous Auxin Indole-3-Acetic Acid

Somatic embryogenesis (SE) is a complex biological process regulated by several factors, such as the action of plant growth regulators, namely auxins, of which the most physiologically relevant is indole-3-acetic acid (IAA). In tamarillo, an optimized system for induction of SE creates, after an induction process, embryogenic (EC) and non-embryogenic callus (NEC). In this work the endogenous levels of auxin along the induction phase and in the calli samples were investigated using chemical quantifications by colorimetric reactions and HPLC as well as immunohistochemistry approaches. Differential gene expression (IAA 11, IAA 14, IAA 17, TIR 1, and AFB3) analysis during the induction phase was also carried out. The results showed that the endogenous IAA content is considerably higher in embryogenic than in non-embryogenic calli, with a tendency to increase as the dedifferentiation of the original explant (leaf segments) evolves. Furthermore, the degradation rates of IAA seem to be related to these levels, as non-embryogenic tissue presents a higher degradation rate. The immunohistochemical results support the quantifications made, with higher observable labeling on embryogenic tissue that tends to increase along the induction phase. Differential gene expression also suggests a distinct molecular response between EC and NEC.

Human Umbilical Cord Mesenchymal Stem Cells Derived Exosomes Promote Neurological Function Recovery in a Rat Spinal Cord Injury Model

Spinal cord injury (SCI) often leads to personal and social-economic consequences with limited therapeutic options. Exosomes derived from human umbilical cord mesenchymal stem cells (hUC-MSC) have been explored as a promising alternative to cell therapies. In the current study, we explored the mechanism of hUC-MSC derived exosome's ameliorative effect on the spinal cord injury by combining data from in vivo contusion SCI model and in vitro cell viability of PC12 cell line stimulated with lipopolysaccharide. Intravenous administration of hUC-MSC derived exosomes dramatically improved motor function of Sprague-Dawley rats after SCI, with reduced apoptosis demonstrated by increased expression of B-cell lymphoma 2 (BCL2), decreased BCL2 associated X, apoptosis regulator (Bax), and reduced cleaved caspase 9. Conversely, exosome treatment reduced the transcription levels of astrocytes marker GFAP and microglia marker IBA1, suggesting a reduced inflammatory state from SCI injury. Furthermore, exosome treatment in vitro increased the cell viability of PC12 cells. Exosome application activated the Wnt/β-Catenin signaling in the spinal cord. Our study demonstrated that hUC-MSC derived exosomes could improve motor function through anti-apoptosis and anti-inflammatory effects. BCL2/Bax and Wnt/β-catenin signaling pathways were involved in the SCI process and could potentially mediate the protective effect of hUC-MSC derived exosomes.

Somatic Embryogenesis of Norway Spruce and Scots Pine: Possibility of Application in Modern Forestry

Somatic embryogenesis (SE) is an important method for the vegetative propagation of trees. SE is the developmental in vitro process in which embryos are produced from somatic cells. This method can be integrated with other biotechnological techniques, genomic breeding and cryopreservation, which enables commercial-scale sapling production of selected high-yielding genotypes in wood production combined with fast breeding cycles. The SE is potential tool to improve plant stock in comparison with seed orchards. It can be useful for ecologically and economically important species, such as Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.), ensuring stable production in the era of climate change and biodiversity crisis. In this review, we summarize the current state of research on problems associated with somatic embryogenesis in P. abies and P. sylvestris.

Transduction of Signals during Somatic Embryogenesis

Somatic embryogenesis (SE) is an in vitro biological process in which bipolar structures (somatic embryos) can be induced to form from somatic cells and regenerate into whole plants. Acquisition of the embryogenic potential in culture is initiated when some competent cells within the explants respond to inductive signals (mostly plant growth regulators, PRGs), and de-differentiate into embryogenic cells. Such cells, "canalized" into the embryogenic developmental pathway, are able to generate embryos comparable in structure and physiology to their in vivo counterparts. Genomic and transcriptomic studies have identified several pathways governing the initial stages of the embryogenic process. In this review, the authors emphasize the importance of the developmental signals required for the progression of embryo development, starting with the de-differentiation of somatic cells and culminating with tissue patterning during the formation of the embryo body. The action and interaction of PGRs are highlighted, along with the participation of master regulators, mostly transcription factors (TFs), and proteins involved in stress responses and the signal transduction required for the initiation of the embryogenic process.

Overview of Somatic Embryogenesis

Somatic embryogenesis is a natural phenomenon through which somatic embryos are produced from somatic cells although. It is considered the most efficient morphogenic pathways for plant multiplication. One of the key features of somatic embryogenesis is the use of cellular totipotency, where dedifferentiation is induced to foster cell proliferation, followed by the induction of differentiation using plant growth regulators to produce new plants. There is a cell group with the potential to undergo the somatic embryogenesis pathway through adequate stimulation (plant growth regulators, incubation conditions, and supplementation of the culture medium). There are two somatic embryogenesis pathways in plants: direct and indirect embryogenesis. Direct somatic embryogenesis consists of the formation of embryos directly from isolated cells, without the formation of "callous" tissue. Indirect somatic embryogenesis is characterized by the formation of a callus as a stage that precedes the formation of somatic embryos. It should be stressed that not all plant cells have this morphogenic capacity; consequently, determining the type of factors that drive this type of response has been challenging. This book provides the reader with updated available information on the techniques, relevant protocols, and tools to perform somatic embryogenesis in different plant species for economic purposes.

The Diverse Manifestations of Regeneration and Why We Need to Study Them

For hundreds of years, the question of why some organisms can regenerate missing body parts while others cannot has remained poorly understood. This has been due in great part to the inability to genetically, molecularly, and cellularly dissect this problem for most of the history of the field. It has only been in the past 20-30 years that important mechanistic advances have been made in methodologies that introduce loss and gain of gene function in animals that can regenerate. However, we still have a very incomplete understanding of how broadly regenerative abilities may be dispersed across species and whether or not such properties share a common evolutionary origin, which may have emerged independently or both. Understanding regeneration, therefore, will require rigorously practiced fundamental, curiosity-driven, discovery research. Expanding the number of research organisms used to study regeneration allows us to uncover aspects of this problem we may not yet know exist and simultaneously increases our chances of solving this long-standing problem of biology.

From Plant Survival Under Severe Stress to Anti-Viral Human Defense - A Perspective That Calls for Common Efforts

Reprogramming of primary virus-infected cells is the critical step that turns viral attacks harmful to humans by initiating super-spreading at cell, organism and population levels. To develop early anti-viral therapies and proactive administration, it is important to understand the very first steps of this process. Plant somatic embryogenesis (SE) is the earliest and most studied model for de novo programming upon severe stress that, in contrast to virus attacks, promotes individual cell and organism survival. We argued that transcript level profiles of target genes established from in vitro SE induction as reference compared to virus-induced profiles can identify differential virus traits that link to harmful reprogramming. To validate this hypothesis, we selected a standard set of genes named 'ReprogVirus'. This approach was recently applied and published. It resulted in identifying 'CoV-MAC-TED', a complex trait that is promising to support combating SARS-CoV-2-induced cell reprogramming in primary infected nose and mouth cells. In this perspective, we aim to explain the rationale of our scientific approach. We are highlighting relevant background knowledge on SE, emphasize the role of alternative oxidase in plant reprogramming and resilience as a learning tool for designing human virus-defense strategies and, present the list of selected genes. As an outlook, we announce wider data collection in a 'ReprogVirus Platform' to support anti-viral strategy design through common efforts.

High-frequency direct somatic embryogenesis and plantlet regeneration from date palm immature inflorescences using picloram

BACKGROUND

Date palm (Phoenix dactylifera L.) is a traditional crop in arid and semi-arid areas. Its vegetative propagation can be achieved by offshoots, but possible number of offshoots in mother palm trees is limited. Micropropagation is a highly recommended strategy for obtaining date palm elite cultivars using shoot tip and immature inflorescences. In this study, micropropagation procedure using inflorescence explants of Medjool cv. is described. For culture initiation, explants from different spathe lengths were cultivated on Murashige and Skoog medium (MS) supplemented with picloram at 1.0 and 2.0 mg/l combined with 2iP at 0.5 mg/l alone and with both 2iP and BA at 0.25 mg/l for 24 weeks. The obtained direct globular embryos were transferred to maturation media with 0.1 mg/l picloram alone or combined with both 2iP and ABA separately and together for further development. Additionally, multiplication and rooting media were optimized by different cytokinins and auxins for high frequency of plantlet production. Acclimatization of in vitro plantlets was also investigated.

RESULTS

The highest percentage of globular embryo formation was noticed with explants isolated from spathe lengths ranging from 10 to 15 cm. Addition of BA to initiation media with picloram encouraged a significant effect on embryonic culture formation percentage. Incorporation of ABA and 2iP to maturation medium was an effective factor for individual or multiple embryo emergence. Acclimatization of in vitro plantlets having 3-4 roots was successfully accomplished. Irrigation with the full strength solution (MS) encouraged the highest growth vigor degree, leaf number/plant, leaf width, root number, and root thickness degree of ex vitro plants.

CONCLUSION

This research provides an advanced regeneration system for large-scale production of date palm from immature inflorescences of Medjool cv. It opens up the prospects of using picloram with different growth regulators for rapid micropropagation of date palm.

Somatic Embryo Yield and Quality From Norway Spruce Embryogenic Tissue Proliferated in Suspension Culture

Somatic embryogenesis is being piloted for the commercial production of genetically improved Norway spruce (Picea abies L. Karst) forest regeneration material in Finland. The main challenge to making the process commercially relevant is the dependence on time-consuming and highly skilled manual labor. Automation and scaling up are needed to improve cost-effectiveness. Moving from the proliferation of embryogenic tissue on semisolid media to suspension cultures could improve process scalability. In a series of four experiments (overall, with 20 cell lines, 4-9 per experiment), the suitability of proliferation in suspension culture for Norway spruce somatic embryogenesis was evaluated based on the growth rate, indicators of stress conditions, good-quality cotyledonary embryo yield, and embling survival in a greenhouse. The proliferation rate in suspension was found equal to on semisolid media, but with a remarkable genotypic variation. Embryogenic tissue matured directly without pre-treatments from suspension onto semisolid media produced lower numbers of good-quality embryos than tissue matured from semisolid media. Rinsing the suspension-grown tissue with hormone-free liquid media before maturation improved embryo yield, bringing it closer to that of semisolid-grown tissue. Decreasing 6-benzylaminopurine and 2,4-dichlorophenoxyacetic acid concentrations in suspension proliferation media to 0.5 or 0.1 times those in semisolid media did not affect tissue growth and did not improve embryo production. The hydrogen peroxide (H₂O₂) content and guaiacol peroxidase activity were elevated in suspension cultures compared with semisolid medium, which had the same plant growth regulator content. In one experiment out of four, the greenhouse survival of germinants was lower when proliferation was carried out in full strength suspension than on semisolid media; in other experiments the survival rates were equal.