Secondary metabolite fingerprinting, anti-pathogenic activity, elite chemotype selection and conservation of Curcuma caesia- an ethnomedicinally underutilized species

Curcuma caesia Roxb. is an ethnomedicinally important, essential oil (EO) yielding aromatic plant. A total of twelve accessions of this plant rhizome were collected from six different agro-climatic zones of West Bengal, India and evaluated for their antimicrobial activities against eight disease-causing, multi-drug-resistant pathogenic strains of urinary-tract infection and respiratory-tract infection. The EO and extracts demonstrated antibacterial activity, with the highest inhibition zone of 18.00 ± 0.08 and 17.50 ± 0.14 mm against Klebsiella pneumoniae by accession 06, even where all the broad-spectrum antibiotics failed to respond. In this study, we employed high-performance thin-layer chromatography (HPTLC) to quantify curcumin, the primary secondary metabolite of C. caesia, and the highest 0.228 mg/gm of curcumin resulted from accession 06. Hence, on the basis of all aspects, accession 06 was identified as the elite chemotype among all twelve accessions. The chemical profiling of EO from accession 06 was done using gas chromatography-mass spectroscopy (GC-MS). Conceivably, about 13 medicinally significant compounds were detected. As this plant species is seasonal and has difficulties in conventional breeding due to dormancy, it must be conserved through in vitro tissue culture for a steady supply throughout the year in massive amounts for agricultural demand. A maximum number of 19.28 ± 0.37 shoots has been obtained in MS medium fortified with 6-Benzylaminopurine, Kinetin, and Naphthalene acetic acid. The genetic uniformity of the plants has been studied through Start Codon Targeted Polymorphism. Therefore, this study must help meet the need for essential phytoactive compounds through a simple, validated, and reproducible plant tissue culture protocol throughout the year.

Recent advances in plant-based bioproduction

Unable to move on their own, plants have acquired the ability to produce a wide variety of low molecular weight compounds to survive against various stresses. It is estimated that there are as many as one million different kinds. Plants also have the ability to accumulate high levels of proteins. Although plant-based bioproduction has traditionally relied on classical tissue culture methods, the attraction of bioproduction by plants is increasing with the development of omics and bioinformatics and other various technologies, as well as synthetic biology. This review describes the current status and prospects of these plant-based bioproduction from five advanced research topics, (i) de novo production of plant-derived high value terpenoids in engineered yeast, (ii) biotransformation of plant-based materials, (iii) genome editing technology for plant-based bioproduction, (iv) environmental effect of metabolite production in plant factory, and (v) molecular pharming.

Transcriptome analysis reveals the effect of propyl gallate on kiwifruit callus formation

KEY MESSAGE

Exploring the potential action mechanisms of reactive oxygen species during the callus inducing, they can activate specific metabolic pathways in explants to regulate callus development. Reactive oxygen species (ROS) play an important role in the regulation of plant growth and development, but the mechanism of their action on plant callus formation remains to be elucidated. To address this question, kiwifruit was selected as the explant for callus induction, and the influence of ROS on callus formation was investigated by introducing propyl gallate (PG) as an antioxidant into the medium used for inducing callus. The results have unveiled that the inclusion of PG in the medium has disturbed the equilibrium of ROS during the formation of the kiwifruit callus. We selected the callus that was induced by the addition of 0.05 mmol/L PG to the MS medium. The callus exhibited a significant difference in the amount compared to the control medium without PG. The callus induced by the MS medium without PG was used as the control for comparison. KEGG enrichment indicated that PG exposure resulted in significant differences in gene expression in related pathways, such as phytohormone signaling and glutathione in kiwifruit callus. Weighted gene co-expression analysis indicated that the pertinent regulatory networks of both ROS and phytohormone signaling were critical for the establishment of callus in kiwifruit leaves. In addition, during the process of callus establishment, the ROS level of the explants was also closely related to the genes for transmembrane transport of substances, cell wall formation, and plant organ establishment. This investigation expands the theory of ROS-regulated callus formation and presents a new concept for the expeditious propagation of callus in kiwifruit.

Enhanced azadirachtin production in neem (Azadirachta indica) callus through NaCl elicitation: Insights into differential protein regulation via shotgun proteomics

With their remarkable bioactivity and evolving commercial importance, plant secondary metabolites (PSMs) have gained significant research interest in recent years. Plant tissue culture serves as a credible tool to examine how abiotic stresses modulate the production of PSMs, enabling clear insights into plant stress responses and the prospects for controlled synthesis of bioactive compounds. Azadirachta indica, or neem has been recognized as a repository of secondary metabolites for centuries, particularly for the compound named azadirachtin, due to its bio-pesticidal and high antioxidant properties. Introducing salt stress as an elicitor makes it possible to enhance the synthesis of secondary metabolites, specifically azadirachtin. Thus, in this research, in vitro callus cultures of neem were micro-propagated and induced with salinity stress to explore their effects on the production of azadirachtin and identify potential proteins associated with salinity stress through comparative shotgun proteomics (LCMS/MS). To induce salinity stress, 2-month-old calli were subjected to various concentrations of NaCl (0.05-1.5%) for 4 weeks. The results showed that the callus cultures were able to adapt and survive in the salinity treatments, but displayed a reduction in fresh weight as the NaCl concentration increased. Notably, azadirachtin production was significantly enhanced in the salinity treatment compared to control, where 1.5% NaCl-treated calli produced the highest azadirachtin amount (10.847 ± 0.037 mg/g DW). The proteomics analysis showed that key proteins related to primary metabolism, such as defence, energy, cell structure, redox, transcriptional and photosynthesis, were predominantly differentially regulated (36 upregulated and 93 downregulated). While a few proteins were identified as being regulated in secondary metabolism, they were not directly involved in the synthesis of azadirachtin. In conjunction with azadirachtin elicitation, salinity stress treatment could therefore be successfully applied in commercial settings for the controlled synthesis of azadirachtin and other plant-based compounds. Further complementary omics approaches can be employed to enhance molecular-level modifications, to facilitate large-scale production of bioactive compounds in the future.

Multiplication of Cupressus guadalupensis Using the RITA® Temporary Immersion System

The Guadalupe cypress (Cupressus guadalupensis S. Watson) is an endangered species included in the list of the NOM-059-SEMARNAT-2010. The presence of wild goats in the habitat has been the greatest threat to the propagation and survival of this species. Therefore, there is a need to generate propagation protocols that facilitate the regeneration of the species. Plant tissue culture offers various possibilities that can facilitate the regeneration of species under some risk. Temporary immersion systems have proven to be an option with various advantages in plant tissue culture, such as increasing the number of seedlings generated and reducing production times, compared to semisolid media. The objective of this chapter is to describe a protocol to propagate Guadalupe cypress tissues in a RITA® temporary immersion system.

Temporary Immersion Bioreactors for Sugarcane Multiplication and Rooting

Sugarcane is used to produce sugar, ethanol, and other by-products, so it is considered one of the most important crops worldwide. Using temporary immersion systems for sugarcane micropropagation represents an alternative to reduce the labor force, increase plant development, and improve plant quality. Temporary immersion systems are semi-automated bioreactors designed for the large-scale propagation of tissues, embryos, and organs. These are temporarily exposed in a liquid culture medium under a specific time and immersion frequency. Using this protocol and a temporary immersion bioreactor, it is possible to achieve multiplication and rooting. The use of temporary immersion bioreactors improves the multiplication rate and the rooting of sugarcane, reducing the culture time, labor force, and reagents needed while maintaining high survival rates during acclimatization.

A Comprehensive Protocol for Assembly of Multiple gRNAs into a Direct Vector for Genome Editing in Tomato

The Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas 9 (CRISPR-associated protein 9) is a robust DNA-encoded, RNA-mediated sequence-specific nuclease system widely used for genome editing of various plants. Although there are many reports on the assembly of gRNAs and plant transformation, there is no single resource for the complete gene editing methodology in tomato. This chapter provides a comprehensive protocol for designing gRNAs, their assembly into the vector, plant transformation, and final mutant analysis in tomato.

In vitro and ex vitro propagation of Turkish myrtles through conventional and plantform bioreactor systems

The myrtle (Myrtus communis) plant naturally grows in the temperate Mediterranean and subtropical regions and is used for various purposes; thus, it is among the promising species of horticultural crops. This study aimed to evaluate and compare the performance of different propagation systems, including rooting, solid media propagation, rooting, and with the Plantform bioreactor system, in achieving healthy and rapid growth of four myrtle genotypes with diverse genetic origins and well-regional adaptation. The selection of myrtle genotypes with distinct genetic backgrounds and proven adaptability to specific regions allowed for a comprehensive assessment of the propagation systems under investigation. Present findings proved that the Plantform system, the new-generation tissue culture system, was quite successful in micropropagation and rooting myrtle genotypes. We succeeded in vitro micropropagation and rooting of diverse wild myrtle genotypes, enabling year-round propagation without reliance on specific seasons or environmental conditions. The process involved initiating cultures from explants and multiplying them through shoot proliferation in a controlled environment. This contributes to sustainable plant propagation, preserving and utilizing genetic resources for conservation and agriculture.

Low-cost and automated phenotyping system "Phenomenon" for multi-sensor in situ monitoring in plant in vitro culture

BACKGROUND

The current development of sensor technologies towards ever more cost-effective and powerful systems is steadily increasing the application of low-cost sensors in different horticultural sectors. In plant in vitro culture, as a fundamental technique for plant breeding and plant propagation, the majority of evaluation methods to describe the performance of these cultures are based on destructive approaches, limiting data to unique endpoint measurements. Therefore, a non-destructive phenotyping system capable of automated, continuous and objective quantification of in vitro plant traits is desirable.

RESULTS

An automated low-cost multi-sensor system acquiring phenotypic data of plant in vitro cultures was developed and evaluated. Unique hardware and software components were selected to construct a xyz-scanning system with an adequate accuracy for consistent data acquisition. Relevant plant growth predictors, such as projected area of explants and average canopy height were determined employing multi-sensory imaging and various developmental processes could be monitored and documented. The validation of the RGB image segmentation pipeline using a random forest classifier revealed very strong correlation with manual pixel annotation. Depth imaging by a laser distance sensor of plant in vitro cultures enabled the description of the dynamic behavior of the average canopy height, the maximum plant height, but also the culture media height and volume. Projected plant area in depth data by RANSAC (random sample consensus) segmentation approach well matched the projected plant area by RGB image processing pipeline. In addition, a successful proof of concept for in situ spectral fluorescence monitoring was achieved and challenges of thermal imaging were documented. Potential use cases for the digital quantification of key performance parameters in research and commercial application are discussed.

CONCLUSION

The technical realization of "Phenomenon" allows phenotyping of plant in vitro cultures under highly challenging conditions and enables multi-sensory monitoring through closed vessels, ensuring the aseptic status of the cultures. Automated sensor application in plant tissue culture promises great potential for a non-destructive growth analysis enhancing commercial propagation as well as enabling research with novel digital parameters recorded over time.

Influence of bio fabricated manganese oxide nanoparticles for effective callogenesis of Moringa oleifera Lam

The use of nanoscale fertilizers to boost crop output has increased in recent years. Nanoparticles (NPs) can stimulate the biosynthesis of bioactive compounds in plants. It is the first report on biosynthesized manganese oxide nanoparticles (MnO-NPs) that mediate in-vitro callus induction of Moringa oleifera. To achieve better biocompatibility the leaf extract of Syzygium cumini was used to synthesize MnO-NPs. Scanning electron microscope SEM revealed spherical shaped morphology of MnO-NPs with an average diameter of 36 ± 0.3 nm. Energy-dispersive X-ray spectroscopy (EDX) depicted the formation of pure MnO-NPs. X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) authenticate the crystalline structure. UV-visible absorption spectroscopy depicted the activity of MnO-NPs under visible light. The biosynthesized MnO-NPs were concentration-dependent and revealed promising results in callus induction of Moringa oleifera. It was found that MnO-NPs enhance callus production of Moringa oleifera and keep the callus infection free by providing an optimum environment for rapid growth and development. Therefore MnO-NPs synthesized through the green process can be utilized in tissue culture studies. This study concludes that MnO is one of the essential plant nutrients that have tailored nutritive properties at a nano scale.

Metabolic engineering of the anthocyanin biosynthetic pathway in Artemisia annua and relation to the expression of the artemisinin biosynthetic pathway

Four types of cells were engineered from Artemisia annua to produce approximately 17 anthocyanins, four of which were elucidated structurally. All of them expressed the artemisinin pathway. Artemisia annua is the only medicinal crop to produce artemisinin for the treatment of malignant malaria. Unfortunately, hundreds of thousands of people still lose their life every year due to the lack of sufficient artemisinin. Artemisinin is considered to result from the spontaneous autoxidation of dihydroartemisinic acid in the presence of reactive oxygen species (ROS) in an oxidative condition of glandular trichomes (GTs); however, whether increasing antioxidative compounds can inhibit artemisinin biosynthesis in plant cells is unknown. Anthocyanins are potent antioxidants that can remove ROS in plant cells. To date, no anthocyanins have been structurally elucidated from A. annua. In this study, we had two goals: (1) to engineer anthocyanins in A. annua cells and (2) to understand the artemisinin biosynthesis in anthocyanin-producing cells. Arabidopsis Production of Anthocyanin Pigment 1 was used to engineer four types of transgenic anthocyanin-producing A. annua (TAPA1-4) cells. Three wild-type cell types were developed as controls. TAPA1 cells produced the highest contents of total anthocyanins. LC-MS analysis detected 17 anthocyanin or anthocyanidin compounds. Crystallization, LC/MS/MS, and NMR analyses identified cyanidin, pelargonidin, one cyanin, and one pelargonin. An integrative analysis characterized that four types of TAPA cells expressed the artemisinin pathway and TAPA1 cells produced the highest artemisinin and artemisinic acid. The contents of arteannuin B were similar in seven cell types. These data showed that the engineering of anthocyanins does not eliminate the biosynthesis of artemisinin in cells. These data allow us to propose a new hypothesis that enzymes catalyze the formation of artemisinin from dihydroartemisinic acid in non-GT cells. These findings show a new platform to increase artemisinin production via non-GT cells of A. annua.

In vitro propagation of Codonopsis pilosula (Franch.) Nannf. using apical shoot segments and phytochemical assessments of the maternal and regenerated plants

BACKGROUND

Codonopsis pilosula (Franch.) Nannf. is a medicinal plant traditionally used in China, Korea, and Japan to treat many diseases including poor gastrointestinal function, low immunity, gastric ulcers, and chronic gastritis. The increasing therapeutic and preventive use of C. pilosula has subsequently led to depletion of the natural populations of this species thus necessitating propagation of this important medicinal plant. Here, we developed an efficient and effective in vitro propagation protocol for C. pilosula using apical shoot segments. We tested various plant tissue culture media for the growth of C. pilosula and evaluated the effects of plant growth regulators on the shoot proliferation and rooting of regenerated C. pilosula plants. Furthermore, the tissues (roots and shoots) of maternal and in vitro-regenerated C. pilosula plants were subjected to Fourier-transform near-infrared (FT-NIR) spectrometry, Gas chromatography-mass spectrometry (GC-MS), and their total flavonoids, phenolics, and antioxidant capacity were determined and compared.

RESULTS

Full-strength Murashige and Skoog (MS) medium augmented with vitamins and benzylaminopurine (1.5 mg·L^-1) regenerated the highest shoot number (12 ± 0.46) per explant. MS medium augmented with indole-3-acetic acid (1.0 mg·L^-1) produced the highest root number (9 ± 0.89) and maximum root length (20.88 ± 1.48 mm) from regenerated C. pilosula shoots. The survival rate of in vitro-regenerated C. pilosula plants was 94.00% after acclimatization. The maternal and in vitro-regenerated C. pilosula plant tissues showed similar FT-NIR spectra, total phenolics, total flavonoids, phytochemical composition, and antioxidant activity. Randomly amplified polymorphic DNA (RAPD) test confirmed the genetic fidelity of regenerated C. pilosula plants.

CONCLUSIONS

The proposed in vitro propagation protocol may be useful for the rapid mass multiplication and production of high quality C. pilosula as well as for germplasm preservation to ensure sustainable supply amidst the ever-increasing demand.

Anatomical and physiological responses of Aechmea blanchetiana (Bromeliaceae) induced by silicon and sodium chloride stress during in vitro culture

Salt stress is one of the most severe abiotic stresses affecting plant growth and development. The application of silicon (Si) is an alternative that can increase the tolerance of plants to various types of biotic and abiotic stresses. The objective was to evaluate salt stress's effect in vitro and Si's mitigation potential on Aechmea blanchetiana plants. For this purpose, plants already established in vitro were transferred to a culture medium with 0 or 14 µM of Si (CaSiO₃). After growth for 30 days, a stationary liquid medium containing different concentrations of NaCl (0, 100, 200, or 300 µM) was added to the flasks. Anatomical and physiological analyses were performed after growth for 45 days. The plants cultivated with excess NaCl presented reduced root diameter and effective photochemical quantum yield of photosystem II (PSII) (ΦPSII) and increased non-photochemical dissipation of fluorescence (qN). Plants that grew with the presence of Si also had greater content of photosynthetic pigments and activity of the enzymes of the antioxidant system, as well as higher values of maximum quantum yield of PSII (F_V/F_M), photochemical dissipation coefficient of fluorescence (qP) and fresh weight bioaccumulation of roots and shoots. The anatomical, physiological and biochemical responses, and growth induced by Si mitigated the effect of salt stress on the A. blanchetiana plants cultivated in vitro, which can be partly explained by the tolerance of this species to grow in sandbank (Restinga) areas.

Effect of explant type (leaf, stem) and 2,4-D concentration on callus induction: influence of elicitor type (biotic, abiotic), elicitor concentration and elicitation time on biomass growth rate and costunolide biosynthesis in gazania (Gazania rigens) cell suspension cultures

Gazania rigens (L.) Gaertn. (Asteraceae) is a medicinal plant with high ornamental potential and use in landscaping. The therapeutic potential of sesquiterpene lactones (SLs) as plant natural products for pharmaceutical development has gained extensive interest with costunolide (chemical name: 6E,10E,11aR-6,10-dimethyl-3-methylidene-3a,4,5,8,9,11a-hexahydrocyclodeca[b]furan-2-one) used as a popular herbal remedy due to its anti-cancer, antioxidant, anti-inflammatory, anti-microbial, anti-allergic, and anti-diabetic activities, among others. In the present study, two explant types (leaf, stem) and four 2,4-dichlorophenoxy acetic acid (2,4-D) concentrations (0, 0.5, 1 and 2 mg/L) were tested for callusing potential. The results showed that stem explants treated with 1.5 mg/L 2,4-D exhibited higher callus induction percentage (90%) followed by leaf explants (80%) with 1 mg/L 2,4-D, after a 4-week period. Cell suspension cultures were established from friable callus obtained from stem explants following a sigmoid pattern of growth curve with a maximum fresh weight at 20 days of subculture and a minimum one at 5 days of subculture. In the following stage, the effects of elicitation of cell suspension cultures with either yeast extract (YE) or methyl jasmonate (MeJA), each applied in five concentrations (0, 100, 150, 200 and 250 mg/L) on cell growth (fresh and dry biomass) and costunolide accumulation were tested. After 20 days of culture, YE or MeJA suppressed cell growth as compared to the non-elicited cells, while costunolide accumulation was better enhanced under the effect of 150 mg/L MeJA followed by 200 mg/L YE, respectively. In the subsequent experiment conducted, the optimal concentration of the two elicitors (200 mg/L YE, 150 mg/L MeJA) was selected to investigate further elicitation time (0, 5, 10, 15 and 20 days). The results revealed that YE biotic elicitation stimulated cell growth and costunolide production, being maximum on day 20 for fresh biomass, on day 5 for dry biomass and on day 15 for the bioactive compound. Accordingly, cell growth parameters were maximized under the effect of abiotic elicitation with MeJA for 15 days, while highest costunolide content was achieved after 10 days. Overall, MeJA served as a better elicitor type than YE for biomass and costunolide production. Irrespective of elicitor type, elicitor concentration and elicitation time, maximal response was obtained with 150 mg/L MeJA for 10 days regarding costunolide accumulation (18.47 ppm) and 15 days for cell growth (fresh weight: 954 mg and dry weight: 76.3 mg). The application of elicitors can lead the large quantity of costunolide to encounter extensive range demand through marketable production without endangering of G. rigens.

An interdisciplinary approach towards sustainable and higher steviol glycoside production from in vitro cultures of Stevia rebaudiana

Stevia rebaudiana is one of the vastly acclaimed commercial plant in the world and belongs to Asteraceae family. The exclusive advantage of Stevia over artificial sweeteners is impeccable and targets its potentiality to the presence of diterpene glycosides. Moreover, the flaunting sweetness of steviol glycosides with associated medicinal benefits, turns the plant to be one of the most economic assets, globally. As compared to vegetative propagation through stem-cuttings, plant tissue culture is the most suitable approach in obtaining true-to-type plants of superior quality. During last few decades, significant in vitro propagation methods have been developed and still the research is ongoing. The present review discusses the tissue culture perspectives of S. rebaudiana, primarily focusing on the mineral nutrition, growth regulators and other accessory factors, motioning the optimum growth and development of the plant. Another crucial aspect is the generation of sweeter varieties in order to reduce the bitter-off taste, which is noticed after the consumption of the leaves. The in vitro cultures pose an efficient alternative system for production of steviol glycosides, with higher rebaudioside(s) content. Moreover, the review also covers the recent approaches pertaining to scale-up studies and genome editing perspectives.

In vitro drought stress and drought-related gene expression in banana

BACKGROUND

Banana is largely grown in tropical and subtropical climates. It is rich in various food components and has quite a high economic value. Unavailable ecological and agricultural conditions cause quantitative and qualitative losses in banana cultivation. Along with global climate change, drought stress is becoming prominent day by day.

METHODS AND RESULTS

Micropropagation and rooting performance of Azman and Grand Naine banana cultivars were investigated under in vitro drought stress conditions. The expression levels of four different genes of CDPK gene family in leaf and root tissues of the rooted plants were determined with the use of qRT-PCR. Greater expression levels of four MaCDPK genes were seen in Azman cultivar than in Grand Naine cultivar. MaCDPK9 and MaCDPK21 had greater expression levels in root tissue and MaCDPK1 and MaCDPK40 genes in leaf tissues.

CONCLUSIONS

Response of different banana cultivars to in vitro drought stress was determined in this study. The expression levels of the genes of CDPK gene family with a significant role in drought stress had significant contributions in elucidation of banana plant response to drought stress.

MdBAK1 overexpression in apple enhanced resistance to replant disease as well as to the causative pathogen Fusarium oxysporum

Apple replant disease (ARD) is a complex syndrome caused by various biotic and abiotic stresses contained in replanted soil, leading to reduced plant growth and fruit yields and causing serious economic loss. Breeding disease-resistant varieties is an effective and practical method to control ARD. Effective plant defense depends in part on the plant immune responses induced by the recognition of pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors (PRRs). BAK1 participates in the regulation of plant immunity as an important PRR-binding protein. In this study, MdBAK1 overexpression activated indeterminate immune responses in tissue-cultured apple plants. MdBAK1-overexpressing rooted apple plants exhibited enhanced resistance to ARD, as the inhibition of plant growth was significantly alleviated during the replanted soil treatment. In addition, MdBAK1-overexpressing apple plants showed abolished growth inhibition, wilting and root rot induced by Fusarium oxysporum, which is the main pathogen that causes ARD in China. MdBAK1 overexpression changed the microbial community structure in the rhizosphere soil, as reflected by the increase in bacterial content and the decrease in fungal content, and the root exudates of MdBAK1-overexpressing plants inhibited F. oxysporum spore germination compared with that of wild-type plants. Furthermore, the constitutive immunity and cell necrosis induced by the upregulation of MdBAK1 expression were involved in the inhibition of colonization and expansion of F. oxysporum in host plants. In short, MdBAK1 plays an important role in the regulation of apple resistance to ARD, suggesting that MdBAK1 may be a valuable gene for molecular breeding of ARD resistance.

Somatic embryogenesis from flower tepals of Hippeastrum aiming regeneration of virus-free plants

Hippeastrum hybridum is an important bulbous flower plant in world floriculture, which are propagated conventionally by the technique known as double or twin scales to obtain plants with clonal origin. However, this technique promotes the propagation of systemic diseases, particularly mosaic-inducing viruses. The aim of this paper was to evaluate the somatic embryogenesis (SE) from tepals as an alternative to provide a technique for SE induction and to obtaining virus-free plantlets of Hippeastrum from infected plants. The concentrations of 2,4-Dichlorofenoxiacetic Acid (2,4-D) and thidiazuron (TDZ) was evaluated in SE induction pathway. The monitoring of viruses during the assays with tepals was performed by Reverse Transcription-Polymerase Chain Reaction. SE induction was obtained, for the first time, in tepal segments from flower buds of Hippeastrum. The 2,4-D was the main factor for embryogenic callus induction, and TDZ increased the SE induction rate. However, conversion of somatic embryos into plantlets were only developed in free-2,4-D media, replaced by 1.0 mg L^-1 6-Benziladenine. Out of five virus species monitored during the experiment, Cucumber mosaic virus was detected in tepals and Hippeastrum mosaic virus in leaves of donor plants. The SE-derived plantlets that germinated in vitro were acclimatized and tested negative for all viruses assayed.

Somatic Embryogenesis of Anthurium andraeanum Linden., -A Tropical Florists' Plant

The global floriculture market is expected to reach US$41.1 billion by 2027 at a CAGR of 5% over the analysis period 2020-2027; on the year 2020, the recorded market value in this trade was US$29.2 billion. The florists mainly use Anthurium andraeanum flowers in fashionable bouquets and floral arrangements because of their beautiful, attractive bright colored eye-catching spathe, candle-like spadix, prolonged vase life, etc. The cut flower industry always seeks elite cultivars and new hybrids of A. andraeanum, that in turn depend on the availability of large numbers of clonal planting propagules. In vitro somatic embryogenesis is an important technique for large-scale clonal propagation, development of transgenic plants, creation of new variety by somaclonal variation, mutagenesis on in vitro plants, and germplasm preservation for future use. Here, we describe the protocol of somatic embryogenesis of Anthurium andraeanum cv. Cancan, an important commercial cultivated variety. The protocol has been optimized by using 4 different types of culture media which are used during embryogenic callus induction, multiplication of callus, induction of somatic embryogenesis, and maturation plus conversion of embryos into plantlets. The protocol outlines the detailed methods from mother plant procurement to hardening of micro plants that is ready to transfer in the field and it can be used for large-scale commercial propagation.

Generation of Stable Catharanthus roseus Hairy Root Lines with Agrobacterium rhizogenes

Agrobacterium rhizogenes is the bacterial agent that causes hairy root disease in dicots and is purposefully engineered for the development of transgenic hairy root cultures. Due to their genetic and metabolic stability, hairy root cultures offer advantages as a tissue culture system for investigating the function of transgenes and as a production platform for specialized metabolites or proteins. The process for generating hairy root cultures involves first infecting the explant with A. rhizogenes, excising and eliminating A. rhizogenes from the emerging hairy roots, selecting for transgenic hairy roots on plates containing the selective agent, confirming genomic integration of transgenes by PCR, and finally adapting the hairy roots in liquid media. Here we provide a detailed protocol for developing and maintaining transgenic hairy root cultures of our medicinal plant of interest, Catharanthus roseus.

Production of bioactive plant secondary metabolites through in vitro technologies-status and outlook

Medicinal plants have been used by mankind since ancient times, and many bioactive plant secondary metabolites are applied nowadays both directly as drugs, and as raw materials for semi-synthetic modifications. However, the structural complexity often thwarts cost-efficient chemical synthesis, and the usually low content in the native plant necessitates the processing of large amounts of field-cultivated raw material. The biotechnological manufacturing of such compounds offers a number of advantages like predictable, stable, and year-round sustainable production, scalability, and easier extraction and purification. Plant cell and tissue culture represents one possible alternative to the extraction of phytochemicals from plant material. Although a broad commercialization of such processes has not yet occurred, ongoing research indicates that plant in vitro systems such as cell suspension cultures, organ cultures, and transgenic hairy roots hold a promising potential as sources for bioactive compounds. Progress in the areas of biosynthetic pathway elucidation and genetic manipulation has expanded the possibilities to utilize plant metabolic engineering and heterologous production in microorganisms. This review aims to summarize recent advances in the in vitro production of high-value plant secondary metabolites of medicinal importance.

Key points

• Bioactive plant secondary metabolites are important for current and future use in medicine

• In vitro production is a sustainable alternative to extraction from plants or costly chemical synthesis

• Current research addresses plant cell and tissue culture, metabolic engineering, and heterologous production

Analysis of correlation between seed vigour, germination and multiple shoot induction in soybean (Glycine max L. Merr.)

The physical and physiological roles of seed properties are often neglected during plant tissue culture. These properties determine the level of activity and performance of seeds, which is commonly known as seed vigour. This paper reports on the role of seed vigour on seed germination and shoot induction using cotyledonary node explants. For this, explants prepared from soybean seedlings established using seeds stored under ambient conditions for different durations (0, 3, 6 and 9-months) were used. The findings indicated that seed germination was highly instantaneous after harvest and began to decrease as seed storage was prolonged for 3, 6 and 9-months, respectively. Similar observations were made during shoot induction. Generally, the analysis revealed a positive relationship between seed vigour, germination and multiple shoot initiation as indicated by the Pearson's correlation coefficient reported. According to the findings, seed vigour could serve as a major obstacle to efficient germination and shoot proliferation for subsequent in vitro plant regeneration.

Shed-Microspore Culture in Ornamental Peppers for Doubled Haploid Plant Production

The shed-microspore culture technique is an alternative sub-method combining anther and isolated microspore culture to induce microspore embryogenesis. Recently, its effective use in different types of peppers has drawn attention, because it has a higher embryo yield potential compared to anther culture and is more practical than isolated microspore culture. In this chapter, a stepwise protocol for shed-microspore culture of ornamental pepper is described. This protocol includes the steps of donor plant growth conditions, the choice of suitable flower buds based on DAPI staining of microspores, application of a cold pretreatment to flower buds, surface sterilization of the buds, shed-microspore culture of anthers, stress treatments, regeneration of androgenic in vitro plantlets, their acclimatization and ploidy analysis, and in vivo chromosome doubling of the haploid plants.

Modeling and optimizing callus growth and development in Cannabis sativa using random forest and support vector machine in combination with a genetic algorithm

Plant callus is generally considered to be a mass of undifferentiated cells and can be used for secondary metabolite production, physiological studies, and plant transformation/regeneration. However, there are several types of callus with different morphological and developmental characteristics and not all are suitable for all applications. Callogenesis is a multivariable developmental process affected by several intrinsic and extrinsic factors, but the most important driver is plant growth regulator (PGRs) levels and type. Since callogenesis is a non-linear process influenced by many different factors, robust computational methods such as machine learning algorithms have great potential to model, predict, and optimize callus growth and development. The current study was conducted to evaluate the effect of PGRs on callus morphology in drug-type Cannabis sativa to maximize callus growth and promote embryogenic callus production. For this aim, random forest (RF) and support vector machine (SVM) were applied in conjunction with image processing to model and predict callus morphological and physical traits. The results showed that SVM was more accurate than RF. In order to find the optimal level of PGRs for optimizing callus growth and development, the SVM was linked to a genetic algorithm (GA). To confirm the reliability of SVM-GA, the optimized-predicted outcomes were tested in a validation experiment that revealed SVM-GA was able to accurately model and optimize the system. Moreover, our results showed that there is a significant correlation between embryogenic callus production and the true density of callus. KEY POINTS: • The effect of PGRs on callus growth and development of cannabis was studied. • The predictive accuracy of SVM and RF was evaluated and compared. • GA was linked to the SVM for optimizing the callus growth and development.

In vitro adventitious roots: a non-disruptive technology for the production of phytoconstituents on the industrial scale

The current trends of consumer-driven demands for natural therapeutics and the availability of evidence-based phytopharmaceuticals from traditional knowledge has once again brought the medicinal plants into forefront of health. In 2019, World Health Organization global report on traditional and complementary medicine has also substantiated the revival of herbal medicine including its convergence with conventional medicine for the management and prevention of diseases. It means these industries need plenty of plant materials to meet the unprecedented demands of herbal formulations. However, it is pertinent to mention here that around 70-80% medicinal plants are sourced from the wild and most of such highly acclaimed plants are listed under Rare, Endangered and Threatened species by IUCN. Additionally, over 30% traditional health formulations are based on underground plant parts, which lead to the uprooting of plants. Overharvesting from limited plant populations, meager conventional cultivation and a rising fondness for natural products exerting enormous pressure on natural habitats. Therefore, the nondestructive means of phytochemical production employing biotechnological tools could be used for sustainable production and consumption patterns. In recent years, a number of reports described the use of adventitious roots induced under in vitro conditions for the extraction of phytochemicals on a sustainable basis. In this article, efforts are made to review recent developments in this area as well as understand the induction mechanisms of adventitious roots, their in vitro cultivation, probable factors that affect the growth and metabolite production, and assess the possibility of industrial scale production to meet the rising demands of natural herbs.

Tissue culture-induced DNA methylation in crop plants: a review

Plant tissue culture techniques have been extensively employed in commercial micropropagation to provide year-round production. Tissue culture regenerants are not always genotypically and phenotypically similar. Due to the changes in the tissue culture microenvironment, plant cells are exposed to additional stress which induces genetic and epigenetic instabilities in the regenerants. These changes lead to tissue culture-induced variations (TCIV) which are also known as somaclonal variations to categorically specify the inducing environment. TCIV includes molecular and phenotypic changes persuaded in the in vitro culture due to continuous sub-culturing and tissue culture-derived stress. Epigenetic variations such as altered DNA methylation pattern are induced due to the above-mentioned factors. Reportedly, alteration in DNA methylation pattern is much more frequent in the plant genome during the tissue culture process. DNA methylation plays an important role in gene expression and regulation of plant development. Variants originated in tissue culture process due to heritable methylation changes, can contribute to intra-species phenotypic variation. Several molecular techniques are available to detect DNA methylation at different stages of in vitro culture. Here, we review the aspects of TCIV with respect to DNA methylation and its effect on crop improvement programs. It is anticipated that a precise and comprehensive knowledge of molecular basis of in vitro-derived DNA methylation will help to design strategies to overcome the bottlenecks of micropropagation system and maintain the clonal fidelity of the regenerants.

Ploidy Modification for Plant Breeding Using In Vitro Organogenesis: A Case in Eggplant

The use of antimitotic agents such as colchicine has been common to obtain polyploid organisms. However, this approach entails certain problems, from its toxicity to the operators for being carcinogenic compounds to the instability of the individuals obtained, and the consequent reversion to its original ploidy because the individuals obtained in most cases are chimeric. In vitro culture allows taking advantage of the full potential offered by the cellular totipotence of plant organisms. Based on this, we present a new in vitro culture protocol to obtain polyploid organisms using zeatin riboside (ZR) and eggplant as a model organism. Flow cytometry is used to identify tetraploid regenerants. The regeneration of whole plants from the appropriate tissues using ZR allowed developing polyploid individuals in eggplant, a crop that tends to be recalcitrant to in vitro organogenesis. Thanks to the use of the polysomatic pattern of the explants, we have been able to develop a methodology that allows to obtain stable non-chimeric polyploid individuals from organogenic processes.

Generation of Transgenic Rice Expressing CircRNA and Its Functional Characterization

Circular RNA (CircRNA) is yet another vital addition to the noncoding RNA family. They are mainly derived by fusion of downstream 3' splice donor with upstream 5' splice acceptor by a noncanonical form of alternative splicing mechanism called backsplicing. An array of functional aspects of these circRNAs has been reported in animal systems. However, functional investigation of circRNA in plants is very limited. In this chapter, we described a methodological outline to study the circRNA biogenesis and to characterize its function(s). Sequence of a newly identified Oryza sativa Indica circRNA flanked by complementary repeat sequences of a rice intron was assembled to yield a circRNA expression cassette. This cassette can be cloned into any plant expression vector which has a suitable promoter (CaMV 35S or ubiquitin promoter) and terminator, and can be used for any circRNA-mediated functional studies. Subsequent agroinfection of rice calli with this cassette yielded circRNA expressing transgenic plants. These transgenic plants were used to establish a correlation between the expressing circRNA, parental gene, and interacting miRNAs. Moreover, effect of circRNA overexpression on plant phenotype under various stress conditions can be studied using these transgenic plants. Also, RNA pull-down assay can be performed to identify the circRNA interacting proteins and the expression of these RBPs can also be studied from these transgenic plants.

Global 5-methylcytosine and physiological changes are triggers of indirect somatic embryogenesis in Coffea canephora

Indirect somatic embryogenesis (ISE) establishment for Coffea species started in the 1970s. Since then, intraspecific variations in the morphogenic pathway have been reported, even in the common environmental condition in vitro. Several authors have suggested that these variations are the result of genetic, epigenetic, and/or physiological events, highlighting the need for investigations to know the causes. Along these lines, this study aimed to investigate and describe, for the first time, the global 5-methylcytosine and physiological changes that occur in the cells of the aggregate suspensions of Coffea canephora during proliferation and somatic embryo regeneration steps. The cell proliferation step was characterized by increase in cell mass in all subcultures; relatively low mean values of global 5-methylcytosine (5-mC%), abscisic acid (ABA), and indole-3-acetic acid (IAA); high mean value of 1-aminocyclopropane-1-carboxylic acid (ACC, an ethylene precursor); and increase followed by decrease in spermidine (Spd, a polyamine) level. Therefore, these epigenetic and physiologic aspects promoted the cell proliferation, which is fundamental for ISE. In turn, the somatic embryo regeneration was correlated with global 5-mC% and physiological changes. The competence acquisition, determination, and cell differentiation steps were marked by increases in mean values of 5-mC%, IAA and ABA, and decreases in ACC and Spd, evincing that these changes are the triggers for regeneration and maturation of somatic embryos. Therefore, dynamic and coordinated epigenetic and physiologic changes occur in the cells of the aggregate suspensions during the C. canephora ISE in liquid system.

Impact of sterilants on culture establishment of indigenous Musa L. varieties: a step forward for conservation

In this paper, we are focusing on study of the impact of sterilization on culture establishment of indigenous Musa variety to restore plant diversity and its importance in human life. Biodiversity supports biological system profitability where every species has a significant task to carry out. Biodiversity of plants guarantees an asset for new nourishment harvests and prescriptions. The biodiversity conservation can start from in situ and ex situ techniques. In situ strategies secure the plants in their common natural surroundings, where as ex situ techniques include safeguarding and upkeep of plant species through plant tissue culture technique. Re-establishing Indigenous plant territory is fundamental for conservation of biodiversity. Indigenous plants are those that present normally in a place where they developed. They are the biological premise whereupon the life of animals and human depends. Traditional medicines from plants are significant part of Indian culture. Banana cultivars nowadays are triploid (AAA, AAB, ABB) cross breeds of two species, Musa acuminate Colla (AA) and Musa balbisiana Colla (BB), which separately contribute the A and B genomes. The M. balbisiana which is normally present in North-Eastern belt of India has high nutrients and resistance to biotic and abiotic stresses. Nanjangud rasabale has been found in parts of Mysuru district, known for its stand-out smell, flavor, taste, and time span of sensible convenience anyway incredibly viewed as a jeopardized grouping; red bananas are phenomenal anyway concerning supplement C and potassium, they are better than yellow ones; Meitei Hei is acclaimed for its enjoyableness and incredible alluring quality. It is a cold permissive grouping thriving incredible even at 12-15 °C. The accomplishment of plant tissue culture convention relies upon explant sterilization procedure. Determination of sterilant and time span of introduction are additionally basic on the grounds that the living material should not lose their natural action and just contaminants should be wiped out during cleansing. Surface sanitization of explant is a procedure which includes the drenching of explants into suitable convergence of compound sterilants for a predetermined time bringing about the foundation of a contamination-free culture.

Cryopreservation of carnation (Dianthus caryophyllus L.) and other Dianthus species

This paper reviews the cryopreservation of the ornamental, carnation (Dianthus caryophyllus L.), as an important method for the long-term preservation of this plant's germplasm. Carnation (Dianthus caryophyllus L.) is an important ornamental plant that is used as a potted plant as well as a cut flower. Important Dianthus germplasm would benefit from long-term strategies such as cryopreservation. Unlike the in vitro tissue culture literature of this ornamental, which has been studied in considerable detail, and with several genetic transformation protocols, surprisingly, the literature on its cryopreservation is still fairly scant, with barely two dozen or so studies, mostly having employed shoot tips. Early (< 2007) and more recent (2007-2020) cryopreservation techniques for carnation, including ultra-rapid cooling, encapsulation-vitrification, and encapsulation-dehydration, efficiently replaced programmed slow cooling processes used in early studies in the 1980s. Two large gaps (1997-2006, and 2016-2020) in which no carnation cryopreservation studies were published, requires future studies to cover new knowledge to fill gaps in information. Carnation cryopreservation research would benefit from testing a wide range of in vitro explants, new techniques such as the cryo-mesh, improved regeneration protocols for post-cryopreserved material, and the use of low-temperature storage as a mid- to long-term complementary germplasm storage strategy. This mini-review provides details of what has been achieved thus far and future objectives that could fortify cryopreservation research of this ornamental, as well as provide a robust long-term germplasm repository.

Physiological parameters and differential expression analysis of N-phenyl-N'-[6-(2-chlorobenzothiazol)-yl] urea-induced callus of Eucalyptus urophylla × Eucalyptus grandis

In this study, we analyzed differences in the enzyme activities and transcriptomes of embryogenic and non-embryogenic calli to gain insights for improving the success of tissue culture-based breeding. A total of 2,856 differentially expressed genes (DEGs; 1,632 up-regulated and 1,224 down-regulated) were identified based on RNA sequencing and verified by reverse transcription quantitative polymerase chain reaction. Gene set enrichment analysis revealed that many of the up-regulated DEGs in embryogenic callus were enriched in the photosynthesis processes. Furthermore, the enzyme activity, hormone content, and cytokinin oxidase/dehydrogenase (CKX) gene expression analyses were found to be consistent with the transcriptome results. Cytokinin biosynthesis in N-phenyl-N′-[6-(2-chlorobenzothiazol)-yl] urea (PBU)-induced embryogenic callus increased owing to CKX repression. Measurement of endogenous hormones by high-performance liquid chromatography revealed that, compared with non-embryogenic callus, in embryogenic callus, the indole-3-acetic acid, abscisic acid and trans-zeatin riboside content had significantly higher values of 129.7, 127.8 and 78.9 ng/g, respectively. Collectively, the findings of this study will provide a foundation for elucidating the molecular mechanisms underlying embryogenic callus differentiation and can potentially contribute to developing procedures aimed at enhancing the success of callus-based plant regeneration.

Blue and red light affects morphogenesis and 20-hydroxyecdisone content of in vitro Pfaffia glomerata accessions

The combination of different colors from light-emitting diodes (LEDs) may influence growth and production of secondary metabolites in plants. In the present study, the effect of light quality on morphophysiology and content of 20-hydroxyecdysone (20E), a phytoecdysteroid, was evaluated in accessions of an endangered medicinal species, Pfaffia glomerata, grown in vitro. Two accessions (Ac22 and Ac43) were cultured in vitro under three different ratios of red (R) and blue (B) LEDs: (i) 1R:1B, (ii) 1R:3B, and (iii) 3R:1B. An equal ratio of red and blue light (1R:1B) increased biomass accumulation, anthocyanin content, and 20E production (by 30-40%). Moreover, 1R:1B treatment increased the size of vascular bundles and vessel elements, as well as strengthened xylem lignification and thickening of the cell wall of shoots. The 1R:3B treatment induced the highest photosynthetic and electron transport rates and enhanced the activity of oxidative stress-related enzymes. Total Chl content, Chl/Car ratio, and NPQ varied more by accession type than by light source. Spectral quality affected primary metabolism differently in each accession. Specifically, in Ac22 plants, fructose content was higher under 1R:1B and 1R:3B treatments, whereas starch accumulation was higher under 1R:3B, and sucrose under 3R:1B. In Ac43 plants, sugars were not influenced by light spectral quality, but starch content was higher under 3R:1B conditions. In conclusion, red and blue LEDs enhance biomass and 20E production in P. glomerata grown in vitro.

Improvement of phytochemical production by plant cells and organ culture and by genetic engineering

Plants display an amazing ability to synthesize a vast array of secondary metabolites that are an inexhaustible source of phytochemicals, bioactive molecules some of which impact the human health. Phytochemicals present in medicinal herbs and spices have long been used as natural remedies against illness. Plant tissue culture represents an alternative to whole plants as a source of phytochemicals. This approach spares agricultural land that can be used for producing food and other raw materials, thus favoring standardized phytochemical production regardless of climatic adversities and political events. Over the past 20 years, different strategies have been developed to increase the synthesis and the extraction of phytochemicals from tissue culture often obtaining remarkable results. Moreover, the availability of genomics and metabolomics tools, along with improved recombinant methods related to the ability to overexpress, silence or disrupt one or more genes of the pathway of interest promise to open new exciting possibilities of metabolic engineering. This review provides a general framework of the cellular and molecular tools developed so far to enhance the yield of phytochemicals. Additionally, some emerging topics such as the culture of cambial meristemoid cells, the selection of plant cell following the expression of genes encoding human target proteins, and the bioextraction of phytochemicals from plant material have been addressed. Altogether, the herein described techniques and results are expected to improve metabolic engineering tools aiming at improving the production of phytochemicals of pharmaceutical and nutraceutical interest.

Artificial color light sources and precursor feeding enhance plumbagin production of the carnivorous plants Drosera burmannii and Drosera indica

Plumbagin is the main pharmacologically active compound of carnivorous plants in the genera Drosera. It possesses various pharmacological activities, including anticancer and antimalarial activities, and is used in traditional medicine. In this study, we reported a sustainable production system of plumbagin by adding sodium acetate and L-alanine as precursors to in vitro cultures of Drosera burmannii Vahl and Drosera indica L. In addition, plumbagin production was reported in the cultures subjected to different color LED lights. The highest plumbagin level (aerial part 14.625 ± 1.007 mg·g^-1 DW and root part 1.806 ± 0.258 mg·g^-1 DW) was observed in D. indica cultured under blue LED light for 14 days, and further culturing did not increase plumbagin production. In addition, plumbagin enhancement by precursor feeding (9.850 ± 0.250 mg·g^-1 DW, 1.2-fold) was observed in the aerial part of D. indica treated with 50 mg·L^-1 sodium acetate for 3 days. Comparing both plants, up to 700-fold higher plumbagin was observed in D. indica than in D. burmannii. Moreover, in both plants, the aerial part accumulated higher plumbagin (up to 10-fold) than the roots. This is the first report on the effect of artificial LED lights on the plumbagin level of Dorsera plants. The culturing of D. indica under blue LED light showed enhanced plumbagin levels and suggests a fast and simple system for the in vitro production of plumbagin.

Rejuvenation of chicory and lettuce plants following phase change in tissue culture

BACKGROUND

A frequent problem associated with the tissue culture of Compositae species such as chicory (Cichorium intybus L.) and lettuce (Lactuca sativa L.) is the premature bolting to in vitro flowering of regenerated plants. Plants exhibiting such phase changes have poor survival and poor seed set upon transfer from tissue culture to greenhouse conditions. This can result in the loss of valuable plant lines following applications of cell and tissue culture for genetic manipulation.

RESULTS

This study demonstrates that chicory and lettuce plants exhibiting stable in vitro flowering can be rejuvenated by a further cycle of adventitious shoot regeneration from cauline leaves. The resulting rejuvenated plants exhibit substantially improved performance following transfer to greenhouse conditions, with increased frequency of plant survival, a doubling of the frequency of plants that flowered, and substantially increased seed production.

CONCLUSION

As soon as in vitro flowering is observed in unique highly-valued chicory and lettuce lines, a further cycle of adventitious shoot regeneration from cauline leaves should be implemented to induce rejuvenation. This re-establishes a juvenile phase accompanied by in vitro rosette formation, resulting in substantially improved survival, flowering and seed set in a greenhouse, thereby ensuring the recovery of future generations from lines genetically manipulated in cell and tissue culture.

Agrobacterium-Mediated Genetic Transformation of Cotton

There are many methods and techniques that can be used to transfer foreign genes into cells. In plant biotechnology, Agrobacterium-mediated transformation is a widely used traditional method for inserting foreign genes into plant genome and obtaining transgenic plants, particularly for dicot plant species. Agrobacterium-mediated transformation of cotton involves several important and also critical steps, which includes co-culture of cotton explants with Agrobacterium, induction and selection of stable transgenic cell lines, recovery of plants from transgenic cells majorly through somatic embryogenesis, and detection and expression analysis of transgenic plants. In this chapter, we describe a detailed step-by-step protocol for obtaining transgenic cotton plants via Agrobacterium-mediated transformation.

De novo in vitro shoot morphogenesis from shoot tip-induced callus cultures of Gymnema sylvestre (Retz.) R.Br. ex Sm

Background

Gymnema sylvestre is a medicinal woody perennial vine known for its sweetening properties and anti-diabetic therapeutic uses in the modern and traditional medicines. Its over-exploitation for the therapeutic uses and to meet the demand of pharmaceutical industry in raw materials supply for the production of anti-diabetic drugs has led to considerable decline in its natural population.

Results

An efficient system of shoot bud sprouting from nodal segment explants and indirect plant regeneration from apical meristem-induced callus cultures of G. sylvestre have been developed on Murashige and Skoog (MS) medium amended with concentrations of cytokinins. Of the three growth regulators tested, N⁶-benzylaminopurine (BAP) was the most efficient and 2.0 mg L⁻¹ gave the best shoot formation efficiency. This was followed by thidiazuron (TDZ) and kinetin (Kin) but, most of the TDZ-induced micro shoots showed stunted growth. Multiple shoot formation was observed on medium amended with BAP or TDZ at higher concentrations. The produced micro shoots were rooted on half strength MS medium amended with auxins and rooted plantlets acclimatized with 87% survival of the regenerates.

Conclusions

The developed regeneration system can be exploited for genetic transformation studies, particularly when aimed at producing its high yielding cell lines for the anti-diabetic phytochemicals. It also offers opportunities for exploring the expression of totipotency in the anti-diabetic perennial vine.

Back to the roots: protocol for the photoautotrophic micropropagation of medicinal Cannabis

The aim of this protocol was to develop an alternative in vitro propagation system for Cannabis sativa L. by mimicking nursery-based vegetative propagation. Photoautotrophic micropropagation (PAM) was achieved on rockwool blocks as substrate combined with commercially available fertilizer suitable for cannabis cultivation. Stock plants were initiated after sterilisation in forced-ventilated glass jars which then provided a continuous supply of shoot tip and nodal cuttings. A 97.5% rooting rate of in vitro shoot tip cuttings and successful acclimatisation were achieved within 3 weeks in glass vessels with passive ventilation.

Uprising the antioxidant power of Argania spinosa L. callus through abiotic elicitation

This study was carried out in order to investigate the ability of tissues of Argania spinosa (L.) to undergo unlimited cell divisions by triggering their proliferative potential via callogenesis. Axenic cultures were efficiently established using axillary buds cultured on half-strength Murashige and Skoog (MS) medium after 20min of surface sterilization with sodium hypochlorite 6% (v/v). The highest callus rate was achieved with 1.0mgL^-1 of naphthaleneacetic acid (NAA) and 1.0mgL^-1 of 2,4-dichlorophenoxyacetic acid (2,4D) or similarly with 0.01mgL^-1 of 6-benzylaminopurine (BAP) and 1.0mgL^-1 of 2,4D at pH of 5.8, under dark conditions. The results of this study show also a significant increase in the callus's antioxidant power under abiotic pressure induced by NaCl. Catalase (CAT), peroxidase (PO), and superoxide dismutase (SOD) activities were significantly triggered, which protected the cells from the stimulated oxidative stress, under hydrogen peroxide (H₂O₂) significant release. This reaction favors subsequently the tissue recover process linked to the low abundance of polyphenol oxidase (PPO) activity and malondialdehyde (MDA) content. This work proves the efficiency of salt stress in boosting the argan cell's antioxidant status, which could be commercially applied in the field of cells regenerative therapy.

Poplar Transformation

First publications of successful Agrobacterium-mediated transformation of tobacco were published more than 30 years ago. Protocols for Agrobacterium-based transformation as well as biolistic bombardment and PEG transformation of protoplasts are available for more than 150 plant species from various plant families. Also for many Populus species and hybrids, adapted transformation protocols have been published. The standard protocol for Agrobacterium-mediated transformation of different Populus genotypes is the leaf-disc method. Here, we first describe the transfer of genes into poplar by using the Agrobacterium-based leaf disc methods. In addition, alternative basic transformation methods, namely, biolistic bombardment and PEG transformation of protoplasts, are also described. Further, we present improved poplar transformation protocols by simplifying the transformation procedure and optimizing tissue preparation and plant regeneration.

Genetic Modification of Grapevine Embryogenic Cultures

Precision breeding is an approach to grapevine genetic improvement that transfers only specific traits among sexually compatible species via the relatively stable mitotic cell division pathway in order to avoid the significant disruption imposed upon conventional breeding by meiosis. Factors enabling precision breeding include the availability of the Vitis genome sequence combined with highly optimized gene insertion and plant regeneration protocols. A protocol for the production of grapevine embryogenic cultures and their genetic transformation is described. Embryogenic cultures are produced from either leaf or floral explants. Somatic embryos at the cotyledonary stage of development are used for Agrobacterium-mediated transformation. Following co-cultivation with Agrobacterium containing the genes of interest, modified embryos are selected on the basis of anthocyanin pigmentation and antibiotic resistance. Somatic embryos are then germinated to produce modified plants that are hardened and transferred to a greenhouse. The presence of the genes of interest is confirmed by PCR.

Alginate immobilization of Morus alba L. cell suspension cultures improved the accumulation and secretion of stilbenoids

Morus alba L. (Moraceae) has been used in traditional medicine for the treatment of several illnesses. Recent research also revealed several pharmacological activities from many groups of secondary metabolites, including the stilbenoids mulberroside A, oxyresveratrol, and resveratrol, which are promising compounds for cosmetic and herbal supplement products. In our previous study, cell cultures of M. alba showed high productivity of these compounds. In this study, we attempted to develop immobilized cell cultures of M. alba and to test the effect of elicitors and precursors on the production of stilbenoids. The immobilization of the M. alba cells significantly promoted the secretion of mulberroside A into the extracellular matrix and culture media to 60%, while enhancing the level of oxyresveratrol and resveratrol by 12- and 27-fold, respectively. The elicitation of immobilized cells with a combination of 50 µM methyl jasmonate and 0.5 mg/mL yeast extract for 24 h promoted a twofold increase in the production of all three stilbenoids. Furthermore, the addition of 0.05 mM L-phenylalanine, 0.03 mM L-tyrosine, or a combination resulted in the enhancement of mulberroside A production for up to twofold. The addition of L-tyrosine significantly enhanced the production of oxyresveratrol and resveratrol. This is the first report of stilbenoid production using immobilized cell cultures of M. alba. The cultures have benefits over normal cell suspension cultures by promoting the secretion of mulberroside A and enhancing the levels of oxyresveratrol and resveratrol. Thus, it could be a candidate method for the production of these stilbenoids.

Anticancer potential of rosmarinic acid and its improved production through biotechnological interventions and functional genomics

Rosmarinic acid (RA) is a highly valued natural phenolic compound that is very commonly found in plants of the families Lamiaceae and Boraginaceae, including Coleus blumei, Heliotropium foertherianum, Rosmarinus officinalis, Perilla frutescens, and Salvia officinalis. RA is also found in other members of higher plant families and in some fern and horned liverwort species. The biosynthesis of RA is catalyzed by the enzymes phenylalanine ammonia lyase and cytochrome P450-dependent hydroxylase using the amino acids tyrosine and phenylalanine. Chemically, RA can be produced via methods involving the esterification of 3,4-dihydroxyphenyllactic acid and caffeic acid. Some of the derivatives of RA include melitric acid, salvianolic acid, lithospermic acid, and yunnaneic acid. In plants, RA is known to have growth-promoting and defensive roles. Studies have elucidated the varied pharmacological potential of RA and its derived molecules, including anticancer, antiangiogenic, anti-inflammatory, antioxidant, and antimicrobial activities. The demand for RA is therefore, very high in the pharmaceutical industry, but this demand cannot be met by plants alone because RA content in plant organs is very low. Further, many plants that synthesize RA are under threat and near extinction owing to biodiversity loss caused by unscientific harvesting, over-collection, environmental changes, and other inherent features. Moreover, the chemical synthesis of RA is complicated and expensive. Alternative approaches using biotechnological methodologies could overcome these problems. This review provides the state of the art information on the chemistry, sources, and biosynthetic pathways of RA, as well as its anticancer properties against different cancer types. Biotechnological methods are also discussed for producing RA using plant cell, tissue, and organ cultures and hairy-root cultures using flasks and bioreactors. The recent developments and applications of the functional genomics approach and heterologous production of RA in microbes are also highlighted. This chapter will be of benefit to readers aiming to design studies on RA and its applicability as an anticancer agent.

Digital Photography as a Tool of Research and Documentation in Plant Tissue Culture

Scientific photography is an important and indispensable tool in plant tissue culture research: photographs should be taken throughout a project for documentation. The aim of photography in plant tissue culture should be to illustrate clearly the differentiation, growth, and developmental stages occurring in vitro. Poor-quality scientific photography in tissue culture research and professional reports results in poor documentation. If visual aspects of the tissue culture are not well documented or not well reproduced in the image, an important part of the research is missed, the resulting report is of limited scientific value, and the research results may not be reproducible. Simple methods for improving the results of photography of materials from plant tissue culture are described and discussed, along with the necessary photographic equipment, suitable backgrounds, the construction of photographic plates, and correct use of electronic files for images. Finally, ethical concerns about image manipulation are discussed.

In vitro plant tissue culture: means for production of biological active compounds

MAIN CONCLUSION

Plant tissue culture as an important tool for the continuous production of active compounds including secondary metabolites and engineered molecules. Novel methods (gene editing, abiotic stress) can improve the technique. Humans have a long history of reliance on plants for a supply of food, shelter and, most importantly, medicine. Current-day pharmaceuticals are typically based on plant-derived metabolites, with new products being discovered constantly. Nevertheless, the consistent and uniform supply of plant pharmaceuticals has often been compromised. One alternative for the production of important plant active compounds is in vitro plant tissue culture, as it assures independence from geographical conditions by eliminating the need to rely on wild plants. Plant transformation also allows the further use of plants for the production of engineered compounds, such as vaccines and multiple pharmaceuticals. This review summarizes the important bioactive compounds currently produced by plant tissue culture and the fundamental methods and plants employed for their production.

Application of Tissue Culture and Transformation Techniques in Model Species Brachypodium distachyon

Brachypodium distachyon has recently emerged as a model plant species for the grass family (Poaceae) that includes major cereal crops and forage grasses. One of the important traits of a model species is its capacity to be transformed and ease of growing both in tissue culture and in greenhouse conditions. Hence, plant transformation technology is crucial for improvements in agricultural studies, both for the study of new genes and in the production of new transgenic plant species. In this chapter, we review an efficient tissue culture and two different transformation systems for Brachypodium using most commonly preferred gene transfer techniques in plant species, microprojectile bombardment method (biolistics) and Agrobacterium-mediated transformation.In plant transformation studies, frequently used explant materials are immature embryos due to their higher transformation efficiencies and regeneration capacity. However, mature embryos are available throughout the year in contrast to immature embryos. We explain a tissue culture protocol for Brachypodium using mature embryos with the selected inbred lines from our collection. Embryogenic calluses obtained from mature embryos are used to transform Brachypodium with both plant transformation techniques that are revised according to previously studied protocols applied in the grasses, such as applying vacuum infiltration, different wounding effects, modification in inoculation and cocultivation steps or optimization of bombardment parameters.

Proteomics as a Tool to Study Molecular Changes During Plant Morphogenesis In Vitro

Proteome analysis represents a promising approach for plant tissue culture since it is now possible to identify and quantify proteins on a large scale. Biomarker discovery and the study of the molecular events associated with in vitro plant morphogenesis are considered potential targets for application of proteomics technologies. This chapter describes a protocol for application in in vitro plant material using two proteomics approaches: 2-DE coupled to mass spectrometry and liquid chromatography-linked tandem mass spectrometry.

Plant Tissue Culture: A Battle Horse in the Genome Editing Using CRISPR/Cas9

Plant tissue culture (PTC) is a set of techniques for culturing cells, tissues, or organs in an aseptic medium with a defined chemical composition, in a controlled environment. Tissue culture, when combined with molecular biology techniques, becomes a powerful tool for the study of metabolic pathways, elucidation of cellular processes, genetic improvement and, through genetic engineering, the generation of cell lines resistant to biotic and abiotic stress, obtaining improved plants of agronomic interest, or studying the complex cellular genome. In this chapter, we analyze in general the use of plant tissue culture, in particular protoplasts and calli, in the implementation of CRISPR/Cas9 technology.

Micropropagation in the Twenty-First Century

Despite more than a century of research on effective biotechnological methods, micropropagation continues to be an important tool for the large-scale production of clonal plantlets of several important plant species that retain genetic fidelity and are pest-free. In some cases, micropropagation is the only technique that supports the maintenance and promotes the economic value of specific agricultural species. The micropropagation of plants solved many phytosanitary problems and allowed both the expansion and access to high-quality plants for growers from different countries and economic backgrounds, thereby effectively contributing to an agricultural expansion in this and the last century. The challenges for micropropagation in the twenty-first century include cost reduction, enhanced efficiency, developing new technologies, and combining micropropagation with other systems/propagation techniques such as microcuttings, hydroponics, and aeroponics. In this chapter, we discuss the actual uses of micropropagation in this century, its importance and limitations, and some possible techniques that can effectively increase its wider application by replacing certain conventional techniques and technologies.