In vitro mutagenesis in anthurium induced by colchicine

Developing new varieties of anthurium by hybridization can take 8-10 years; therefore, induced mutagenesis can be an alternative strategy to hybridization. The objective of this work was to induce mutations in A. andreanum by exposing explants obtained from vitroplants to colchicine. Explants of leaves, nodes and roots obtained from vitroplants were exposed to 0.1 % colchicine for 0, 2, 3 and 4 h. The mean lethal dose (LD50), survival, number of explants that generated callus, number of explants that formed shoots and the number of shoots per explant were evaluated. The karyotype of the presumed mutated regenerated plants was determined by the root apex squash technique. The leaves showed the highest sensitivity to cochicine. The survival of the root explants treated with colchicine was 100 %; 4 % of roots exposed for 2 and 3 h formed adventitious shoots (120 shoots). For nodes, the LD50 was found at 3.98 h; 76 and 56 % of the nodes cultivated for 2 and 3 h with colchicine formed adventitious shoots (4.4 and 3.6 shoots). The plants regenerated from the explants exposed to colchicine showed morphological changes. The chromosomal number of the regenerated vitroplants from the explants exposed for 2 and 3 h to colchicine was 2n = 29, while that of those obtained from the explants that remained on the colchicine for 4 h was 2n = 31. The sensitivity to colchicine was a function of the type of explant and the dose used. Colchicine caused the loss (monosomy) or gain of chromosomes (trisomy).

Indirect in vitro Regeneration of the Medicinal Plant, Aspilia africana, and Histological Assessment at Different Developmental Stages

The medicinal plant, Aspilia africana, has been traditionally used in several African countries to treat many diseases such as tuberculosis, cough, inflammation, malaria, osteoporosis, and diabetes. In this study, we developed a protocol for in vitro propagation of A. africana using indirect shoot organogenesis from leaf and root explants of in vitro-grown seedlings and assessed the tissues at different developmental stages. The highest callus induction (91.9 ± 2.96%) from leaf explants was in the Murashige and Skoog (MS) medium augmented with 1.0 mg/L 6-Benzylaminopurine (BAP) and 1.0 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) while from root explants, the highest callus induction (92.6 ± 2.80%) was in the same plant tissue culture medium augmented with 0.5 mg/L BAP and 1.0 mg/L 2,4-D. The best shoot regeneration capacity from leaf-derived calli (i.e., 80.0 ± 6.23% regeneration percentage and 12.0 ± 6.23 shoots per callus) was obtained in medium augmented with 1.0 mg/L BAP and 0.05 mg/L α-Naphthaleneacetic acid (NAA); the best regeneration capacity for root-derived calli (i.e., 86.7 ± 6.24% shoot regeneration percentage and 14.7 ± 1.11 shoots per callus) was obtained in the MS medium augmented with 1.0 mg/L BAP, 0.05 mg/L NAA, and 0.1 mg/L Thidiazuron (TDZ). Regenerated plantlets developed a robust root system in 1/2 MS medium augmented with 0.1 mg/L NAA and had a survival rate of 93.6% at acclimatization. The in vitro regenerated stem tissue was fully differentiated, while the young leaf tissue consisted of largely unorganized and poorly differentiated cells with large intercellular airspaces typical of in vitro leaf tissues. Our study established a protocol for the indirect regeneration of A. africana and offers a basis for its domestication, large-scale multiplication, and germplasm preservation. To the best of our knowledge, this is the first study to develop an indirect regeneration protocol for A. africana and conduct anatomical assessment through the different stages of development from callus to a fully developed plantlet.

In-vitro propagation and phytochemical profiling of a highly medicinal and endemic plant species of the Himalayan region (Saussurea costus)

Efficient protocols for callus induction and micro propagation of Saussurea costus (Falc.) Lipsch were developed and phytochemical diversity of wild and in-vitro propagated material was investigated. Brown and red compact callus was formed with frequency of 80–95%, 78–90%, 70–95% and 65–80% from seeds, leaf, petiole and root explants, respectively. MS media supplemented with BAP (2.0 mgL−1), NAA (1.0 mgL−1) and GA3 (0.25 mgL−1) best suited for multiple shoot buds initiation (82%), while maximum shoot length was formed on media with BAP (1.5 mgL−1), NAA (0.25 mgL−1) and Kinetin (0.5 mgL−1). Full strength media with IAA (0.5 mgL−1) along with IBA (0.5 mgL−1) resulted in early roots initiation. Similarly, maximum rooting (87.57%) and lateral roots formation (up to 6.76) was recorded on full strength media supplemented with BAP (0.5 mgL−1), IAA (0.5 mgL−1) and IBA (0.5 mgL−1). Survival rate of acclimatized plantlets in autoclaved garden soil, farmyard soil, and sand (2:1:1) was 87%. Phytochemical analysis revealed variations in biochemical contents i.e. maximum sugar (808.32 µM/ml), proline (48.14 mg/g), ascorbic acid (373.801 mM/g) and phenolic compounds (642.72 mgL−1) were recorded from callus cultured on different stress media. Nonetheless, highest flavenoids (59.892 mg/g) and anthocyanin contents (32.39 mg/kg) were observed in in-vitro propagated plants. GC–MS analysis of the callus ethyl acetate extracts revealed 24 different phytochemicals. The variability in secondary metabolites of both wild and propagated plants/callus is reported for the first time for this species. This study may provide a baseline for the conservation and sustainable utilization of S. costus with implications for isolation of unique and pharmacologically active compounds from callus or regenerated plantlets.

High frequency plant regeneration of Chrysopogon zizanioides via organogenesis and somatic embryogenesis-an underutilized pharmaceutically valuable biofuel plant

Vetiver (Chrysopogon zizanioides) is an essential oil-producing plant that has tremendous application in cosmetics, perfumery, and herbal medicine. Natural sterility and indiscriminate harvests lead to the risk of extinction of plant species in natural habitats. Therefore, a protocol for regeneration systems via organogenesis and somatic embryogenesis using node, leaf, and root explants has been standardized. The highest shoot regeneration frequency (72.2%) through organogenesis was attained from node explants on MS (Murashige & Skoog) medium comprising 2.0 mg L-1 BAP (“6-benzylaminopurine”). Concurrently, leaf explants cultivated on MS medium augmented by 1.0 mg L-1, 2, 4-D (“2, 4-dichlorophenoxyacetic acid”) formed the optimal frequency (75.35%) of white friable compact (WFC) callus. However, the root explant was less responsive for WFC callus induction. Organogenic WFC callus cultivated on MS medium fortified by kinetin (1.0 mg L-1) as well as BAP (1.0 mg L-1) revealed the highest shoot regeneration efficiency (75.49%) with 48 shoots per callus. Adventitious shoots obtained from node and WFC callus of both leaf and root explants cultivated on MS medium increased by NAA (2.0 mg L-1 showed the optimal rooting of 76.97%. Concomitantly, an elevated frequency of somatic embryogenesis (52.50%) was recorded from leaf explants on MS medium using BAP (0.5 mg L-1) & 2, 4-D (1.0 mg L-1). Leaf explants were superior to node and root explants for somatic embryo initiation. The cotyledonary embryos were efficiently germinated into complete plantlets on a hormone-free MS medium. The plantlets gathered from organogenesis & somatic embryo genesis was effectively acclimatized into phenomenally similar plants. This technique may be applicable for wide-range propagation, genetic engineering, and the formation of bioactive compounds.

Temporal Control of Morphogenic Factor Expression Determines Efficacy in Enhancing Regeneration

Background: Regeneration of fertile plants from tissue culture is a critical bottleneck in the application of new plant breeding technologies. Ectopic overexpression of morphogenic factors is a promising workaround for this hurdle. Methods: Conditional overexpression of WUS and ARF5Δ was used to study the effect of timing the overexpression of these morphogenic factors during shoot regeneration from root explants in Arabidopsis. In addition, their effect on auxin-signaling activation was examined by visualization and cytometric quantification of the DR5:GFP auxin-signaling reporter in roots and protoplasts, respectively. Results: The induced expression of both WUS and ARF5Δ led to an activation of auxin signaling in roots. Activation of auxin signaling by WUS and ARF5Δ was further quantified by transient transformation of protoplasts. Ectopic overexpression of both WUS and ARF5Δ enhanced regeneration efficiency, but only during the shoot-induction stage of regeneration and not during the callus-induction stage. Conclusions: The overexpression of WUS and ARF5Δ both lead to activation of auxin signaling. Expression during the shoot-induction stage is critical for the enhancement of shoot regeneration by WUS and ARF5Δ.

Effect of Nitrogen on in Vitro Propagation of Endangered Medicinal Plant: Swertia Chirayita Roxb. Ex Flaming

The effect of nitrogen was investigated on the organogenesis of Swertia chirayita (Gentianaceae) to overcome the challenges related to its cultivation. The best callogenic response was observed on root explants inoculated onto MS medium supplemented with BAP (2.0 mg/l) along with 2,4-D (0.5 mg/l) after 35 days of culture. Subsequent transfer of callus for multiplication on the same media composition under complete darkness presents the best results in terms of callus multiplication. Callogenic cultures were subculture onto modified MS medium supplemented with inorganic nitrogen sources, i.e., NH4NO3 (14-56N/l), KNO3 (100-400N/l) with BAP (3.0 mg/l) were observed. Organogenic response (52%) was observed after 8-12 weeks of culturing. The maximum number of the shoot was recorded on MS medium with NH4NO3 (28 N/l), KNO3 (300N/l) with BAP (3.0 mg/l). Moreover, 90% of them were able to regrow when sub-cultured on the same media. Sixteen weeks old multiple shoots were subcultured on MS medium supplemented with different auxins. IAA was proved to be the best hormone rooting purpose. However, the best rooting response regarding the number of roots and an average length of roots was obtained at IAA (1.0 mg/l). Survival of 90% was achieved when rooted plantlets were successfully established in substrate containing sand, vermicompost, and garden soil in equal proportion for hardening and acclimatized.

Inoculum Level and Inoculation Method Influences on the Pathogenic Activities of Meloidogyne incognita in Studied Model Plant Okra (Abelmoschus esculentus L. Moench)

Agricultural activities such as watering crops with nematode-infested water from wells and boreholes, and using infected plant debris as manure or mulch increase root-knot nematode infection. So, this study aims at assessing the influence of the inoculation method and inoculum level of Meloidogyne incognita on the development of root galls on okra plants. Two M. incognita inoculation methods (suspension of individuals and galled root explants) and six inoculum levels (0, 10, 100, 500, 1000 and 2000 second-stage larvae/plant) were studied. The gall index, total numbers and reproductive factor of M. incognita were used to assess the effect of treatments on root gall development. Unlike the reproductive factor, gall index and the total numbers of M. incognita increased with their inoculum level. The pathogenic activities of M. incognita were most significant when crop soils were infested with galled root explants. However, an inverse relationship was found between the inoculum levels of M. incognita and the okra plant’s development. It is reflected by negative correlation coefficients ranging from -0.90 to -0.62. It is therefore important to burn roots infected with root-knot nematodes left in fields so that they do not act as an inoculum for crops.

Micropropagation of Hibiscus moscheutos L. ‘Luna White’: effect of growth regulators and explants on nuclear DNA content and ploidy stability of regenerants

Hibiscus moscheutos L., also known as hardy hibiscus, is valued for its medicinal and ornamental attributes. It is usually propagated via seeds or cuttings. The purpose of this investigation was to develop a dependable micropropagation for H. moscheutos ‘Luna White’. To that end, the effect of four explant types (leaf, root, node, shoot tip) and two growth regulators 6-benzylaminopurine (BA) and meta-Topolin (mT) (6-(3-hydroxybenzylamino) purine) on in vitro growth of H. moscheutos was investigated. Genetic stability of the in vitro grown plants was assessed using flow cytometry, and chromosome count was investigated. No shoots were obtained from leaf or root explants. An efficient protocol for micropropagation of H. moscheutos using two explant types, 2-node and shoot tip explants, and two cytokinins (BA and mT) capable of producing true-to-type regenerants was established. Both BA and mT can be used at 2 μM or 4 μM using either 2-node or shoot tip explants. No significant difference was found between the nuclear DNA contents of seed-derived and in vitro grown plants (P < 0.05). The mean 2C DNA and monoploid 1Cx-values of seed-derived plants were 3.25 ± 0.08 pg and 1.62 ± 0.04 pg, respectively, compared with 3.26 ± 0.06 pg and 1.63 ± 0.02 pg, respectively, for in vitro grown plants. The chromosome number of both seed-derived plants and regenerants was determined to be 2n = 2x = 38. The mature regenerants obtained were fertile and phenotypically similar to seed-derived plants.