The root: a potential new source of competent cells for high-frequency regeneration in Tylophora indica

Phenanthroindolizidine Alkaloids Secondary Metabolites Diversity in Medicinally Viable Plants of the Genus Tylophora

Plants of the genus Tylophora have commonly been used in traditional medicine in various communities, especially in the tropical and subtropical regions of climatic zones. Of the nearly 300 species reported in the Tylophora genus, eight are primarily used in various forms to treat a variety of bodily disorders based on the symptoms. Certain plants from the genus have found use as anti-inflammatory, anti-tumor, anti-allergic, anti-microbial, hypoglycemic, hypolipidemic, anti-oxidant, smooth muscle relaxant, immunomodulatory, and anti-plasmodium agents, as well as free-radical scavengers. Pharmacologically, a few plant species from the genus have exhibited broad-spectrum anti-microbial and anti-cancer activity, which has been proven through experimental evaluations. Some of the plants in the genus have also helped in alcohol-induced anxiety amelioration and myocardial damage repair. The plants belonging to the genus have also shown diuretic, anti-asthmatic, and hepato-protective activities. Tylophora plants have afforded diverse structural bases for secondary metabolites, mainly belonging to phenanthroindolizidine alkaloids, which have been found to treat several diseases with promising pharmacological activity levels. This review encompasses information on various Tylophora species, their distribution, corresponding plant synonyms, and chemical diversity of the secondary metabolic phytochemicals as reported in the literature, together with their prominent biological activities.

Cytokinins: Wide-Spread Signaling Hormones from Plants to Humans with High Medical Potential

Nature is a rich source of biologically active novel compounds. Sixty years ago, the plant hormones cytokinins were first discovered. These play a major role in cell division and cell differentiation. They affect organogenesis in plant tissue cultures and contribute to many other physiological and developmental processes in plants. Consequently, the effect of cytokinins on mammalian cells has caught the attention of researchers. Many reports on the contribution and potential of cytokinins in the therapy of different human diseases and pathophysiological conditions have been published and are reviewed here. We compare cytokinin effects and pathways in plants and mammalian systems and highlight the most important biological activities. We present the strong profile of the biological actions of cytokinins and their possible therapeutic applications.

Anti-neuroinflammatory potential of Tylophora indica (Burm. f) Merrill and development of an efficient in vitro propagation system for its clinical use

Neuroinflammation is a major risk factor associated with the pathogenesis of neurodegenerative diseases. Conventional non-steroidal anti-inflammatory drugs are prescribed but their long term use is associated with adverse effects. Thus, herbal based medicines are attracting major attraction worldwide as potential therapeutic candidates. Tylophora indica (Burm. f) Merrill is a valuable medicinal plant well known in Ayurvedic practices for its immunomodulatory, anti-oxidant, anti-asthmatic and antirheumatic activities. The present study aimed to elucidate the anti-neuroinflammatory potential of water and hydroalcoholic leaf extracts of micropropagated plants of T. indica using BV-2 microglia activated with lipopolysaccharide as an in vitro model system and development of an efficient reproducible protocol for its in vitro cloning. Non cytotoxic doses of the water and hydroalcoholic extracts (0.2μg/ml and 20μg/ml, respectively) were selected using MTT assay. α-Tubulin, Iba-1 and inflammatory cascade proteins like NFκB, AP1 expression was studied using immunostaining to ascertain the anti-neuroinflammatory potential of these extracts. Further, anti-migratory activity was also analyzed by Wound Scratch Assay. Both extracts effectively attenuated lipopolysaccharide induced microglial activation, migration and the production of nitrite via regulation of the expression of NFκB and AP1 as the possible underlying target molecules. An efficient and reproducible protocol for in vitro cloning of T. indica through multiple shoot proliferation from nodal segments was established on both solid and liquid Murashige and Skoog’s (MS) media supplemented with 15μM and 10μM of Benzyl Amino Purine respectively. Regenerated shoots were rooted on both solid and liquid MS media supplemented with Indole-3-butyric acid (5–15μM) and the rooted plantlets were successfully acclimatized and transferred to open field conditions showing 90% survivability. The present study suggests that T. indica may prove to be a potential anti-neuroinflammatory agent and may be further explored as a potential therapeutic candidate for the management of neurodegenerative diseases. Further, the current study will expedite the conservation of T. indica ensuring ample supply of this threatened medicinal plant to fulfill its increasing demand in herbal industry.

Rapid plant regeneration, validation of genetic integrity by ISSR markers and conservation of Reseda pentagyna an endemic plant growing in Saudi Arabia

Reseda pentagyna is the only endemic species among the seven species of the genera Reseda found in Saudi Arabia. Probably no information is available on regeneration by conventional method of regeneration through seeds or cuttings. Therefore, alternative method of tissue culture was attempted to regenerate and multiply the plant. High shoot regeneration (14.44 shoots/explant) was obtained after four weeks, when shoot cuttings cultured on MS containing BA at 1.0 µM. Other cytokinins e.g., Kn, 2iP and TDZ found to be less effective in bud induction and shoot multiplication. Individual shoots were rooted on MS medium supplemented with various auxins at 0.5–5.0 µM concentrations. The IBA (1.5 µM) supplemented MS media induced maximum (83.3%) rooting. The plantlets were acclimatized and hardened under greenhouse conditions in plastic pots containing soil and farm yard manure with 95.0% success. The protocol developed would help to multiply the plant as well as conserve them in natural habitat. This can also be utilized to obtain active constituents for pharmaceutics and genetic manipulations.

Neoteric trends in tissue culture-mediated biotechnology of Indian ipecac [Tylophora indica (Burm. f.) Merrill]

Tylophora indica (Burm. f.) Merrill, an ethno-pharmacologically important perennial climber of Asclepiadaceae, is commonly known as Antamul or Indian ipecac. It is essentially accredited for its medicinal properties owing to its wide range of alkaloids in the form of bioactive secondary metabolites, such as tylophorine, tylophorinine, and tylophorinidine. Accelerated mass propagation of Tylophora is challenging because of its reduced seed germination frequency that consequently headed the pursuit for efficient protocols on in vitro propagation for the large-scale regeneration, conservation as well as sustainable supply of quality propagules. Ample tissue culture-mediated biotechnological investigations have been carried out on this medicinal plant till date and several micropropagation protocols have been standardized as well. The present review compares between several typical methods as well as factors, involving on direct and indirect organogenesis of Tylophora along with various up-to-date and modified techniques such as somatic embryogenesis, protoplast culture, synthetic seed production, genetic transformation, and in vitro interventions for the secondary metabolite production that have been reported in last two decades. This compilation will allow assessing the achievements and trends of Tylophora research so far, as well as will advance the research more rapidly, since many aspects, basic and applied, have yet to be explored.

Micropropagation and genetic transformation of Tylophora indica (Burm. f.) Merr.: a review

This review provides an in-depth and comprehensive overview of the in vitro culture of Tylophora species, which have medicinal properties. Tylophora indica (Burm. f.) Merr. is a climbing perennial vine with medicinal properties. The tissue culture and genetic transformation of T. indica, which has been extensively studied, is reviewed. Micropropagation using nodal explants has been reported in 25 % of all publications. Leaf explants from field-grown plants has been the explant of choice of independent research groups, which reported direct and callus-mediated organogenesis as well as callus-mediated somatic embryogenesis. Protoplast-mediated regeneration and callus-mediated shoot organogenesis has also been reported from stem explants, and to a lesser degree from root explants of micropropagated plants in vitro. Recent studies that used HPLC confirmed the potential of micropropagated plants to synthesize the major T. indica alkaloid tylophorine prior to and after transfer to field conditions. The genetic integrity of callus-regenerated plants was confirmed by RAPD in a few reports. Tissue culture is an essential base for genetic transformation studies. Hairy roots and transgenic T. indica plants have been shown to accumulate tylophorine suggesting that in vitro biology and transgenic methods are viable ways of clonally producing valuable germplasm and mass producing compounds of commercial value. Further studies that investigate the factors affecting the biosynthesis of Tylophora alkaloids and other secondary metabolites need to be conducted using non-transformed as well as transformed cell and organ cultures.

The Fate of Integrated Ri T-DNA rol Genes during Regeneration via Somatic Embryogenesis in Tylophora indica

The fate of integrated Ri T-DNA rol genes during regeneration via indirect somatic embryogenesis and stability of its effect on morphology and tylophorine content of Ri-transformed plants have been studied in Tylophora indica. Integration and expression of Ri T-DNA genes in transformed embryogenic callus lines derived from transformed root lines, 300 Ri-transformed somatic embryos, and 23 Ri-transformed plant lines were analysed. Fifty root lines studied showed integration and expression of four rol genes of TL-DNA. Spontaneous regeneration via indirect somatic embryogenesis was obtained from root lines that were TL+/TR−. Stable integration and expression of rol genes were observed in root lines, embryogenic callus lines, and the spontaneously induced somatic embryos. Nineteen out of the 23 Ri-transformed plant lines and their clones showed phenotypic and genetic stability over the period of 3 years. Four Ri-transformed plants were morphologically similar to nontransformed plants but showed variation with the integration and expression of the rolA gene and absence of other rol genes. Variant Ri-transformed plant line A428#1-V showed highest tylophorine content (2.93±0.03 mg gDW−1) among plant lines studied. The effects of T-DNA genes on growth, morphology, and tylophorine content of the Ri-transformed plants were stable in the long term culture.

Globular body production, their anatomy, DNase gel analysis and NDP kinase activity in root tips of Poncirus trifoliata L

Green globular bodies were developed from Poncirus trifoliata L. root tip explants as a response to addition in the substrate of different growth regulators. From the globular bodies, shoots initiated and grew. Median section of the globular bodies reveals that they are composed of parenchyma cells and originate from the pericycle. The activity of DNases during shoot formation from globular bodies was influenced by the type and concentration of plant growth regulators that were added in the nutrient substrate. Peptide bands formation was also influenced by the increase of BA concentration. Consequently, BA, NAA and IAA combination influenced 5'-triphosphonucleosides (NTPs) appearance and activity in the presence of metal. Peptide bands resulted from the electrophoretic analysis of endogenous protein phosphorylation, proved to be catalytic subunits of NDP kinases, as they all phosphorylate diphosphonucleosides. The enzymes DNases and NDP kinases could be used as a scientific tool for the study of shoot formation from P. trifoliata L. green globular bodies.

Oral administration of low doses of plant-based HBsAg induced antigen-specific IgAs and IgGs in mice, without increasing levels of regulatory T cells

Plant-based oral vaccines run the risk of activating regulatory T cells (Tregs) and suppressing the antigen-specific immune response via oral tolerance. Mice humanized for two HLA alleles (HLA-A2.1 and HLA-DR1) were used to measure changes in Tregs and antigen-specific immune responses induced by the oral administration of tobacco (Nicotiana tabacum), expressing the hepatitis B surface antigen (HBsAg). Antigen-specific CD8+ T cell activation was not detected, but the plant-based oral immunization, without adjuvant, resulted in humoral responses comparable to those obtained by adjuvanted DNA immunization. Treg titers did not increase with DNA immunization. In contrast, with plant immunization, Tregs increased linearly to reach a plateau at high antigen doses. The highest humoral IgA and IgG responses correlated with the lowest plant antigen dose (0.5 ng), while for DNA immunization the best antibody responses were obtained at higher antigen doses. These experiments suggest that plant-based oral vaccines could be adjusted to minimize tolerance, while still inducing an immune response. Oral tolerance and adjuvant engineering in plants are discussed.

Spontaneous plant regeneration in transformed roots and calli from Tylophora indica: Changes in morphological phenotype and tylophorine accumulation associated with transformation by Agrobacterium rhizogenes

We examined the effects of genetic transformation by Agrobacterium rhizogenes on the production of tylophorine, a phenanthroindolizidine alkaloid, in the Indian medicinal plant, Tylophora indica. Transformed roots induced by the bacterium grew in axenic culture and produced shoots or embryogenic calli in the absence of hormone treatments. However, hormonal treatment was required to regenerate shoots in root explants of wild type control plants. Transformed plants showed morphological features typically seen in transgenic plants produced by A. rhizogenes, which include, short internodes, small and wrinkled leaves, more branches and numerous plagiotropic roots. Plants regenerated from transformed roots showed increased biomass accumulation (350-510% in the roots and 200-320% in the whole plants) and augmented tylophorine content (20-60%) in the shoots, resulting in a 160-280% increase in tylophorine production in different clones grown in vitro.

Genetic transformation of Tylophora indica with Agrobacterium rhizogenes A4: growth and tylophorine productivity in different transformed root clones

We have developed an efficient transformation system for Tylophora indica, an important medicinal plant in India, using Agrobacterium rhizogenes strains LBA9402 and A4 to infect excised leaf and stem explants and intact shoots at different sites. The induction of callus and transformed roots was dependent on the bacterial strain, explant type and inoculation site used. Transformed roots were induced only in explants infected with A. rhizogenes strain A4, while an optimal transformation frequency of up to 60% was obtained with intact shoots inoculated at the nodes. The presence of the left-hand transferred DNA (T(L)-DNA) in the genome of T. indica roots induced by A. rhizogenes was confirmed by PCR amplification of the rooting locus genes of A. rhizogenes. Root growth and the production of tylophorine, the major alkaloid of the plant, varied substantially among the nine root clones studied. Both parameters increased over time in liquid cultures, with maximum biomass and tylophorine accumulation occurring within 4-6 weeks of growth in fresh medium. Interestingly, in liquid culture, the culture medium also accumulated tylophorine up to concentrations of 9.78+/-0.21 mg l(-1).