Micropropagation of Dendrobium nobile from shoot tip sections

Micropropagation and assessment of genetic stability of Dendrobium transparens Wall. Ex Lindl. using RAPD and ISSR markers

Introduction

Dendrobium species have been widely used for many health disorders since ancient times. However, due to unrelenting collection to meet the increasing demand for their use in medication and other health products, the natural habitats of medicinal Dendrobium transparens have been devastated and are on the verge of extinction.

Methods

An efficient in-vitro propagation protocol for Dendrobium transparens using seed derived protocorms was established and genetic homogeneity of the in-vitro regenerants and the wild plant was studied.

Results

The maximum seed germination was observed in Full strength Murashige and Skoog medium (FMS). Induction of protocorms were achieved on basal as well as half-strength MS medium. The highest number of shoot (11.9 shoots/explant) was achieved in half MS medium fortified with 100 mL/L coconut water in addition with Benzyl amino purine (BAP) 1 mg/L and Kinetin 2 mg/L. Further, elongated shoots were transferred to full and half strength MS root initiating medium supplemented with different concentration of auxins. However, a maximum of (8.3 ± 0.6, 4.9 ± 0.1 cm) roots were achieved in full MS medium fortified with 100 mL/L coconut water and Napthalene acetic acid (NAA) 1.5 mg/L. Ten rapid Random Amplified Polymorphic DNA (RAPD) and Inter Simple Sequence Repeats (ISSR) primers were used to analyze genetic stability among in-vitro and mother plant. RAPD primers produced a total of 23 fragments while ISSR primers produced a total of 16 fragments.

Conclusion

The amplified bands of all the samples of in-vitro plants were similar to bands of mother plant. The present research reported here is indicating the applicability of tissue culture for true-to-type plant production and conservation of D. transperens.

Tissue Culture in Ornamentals: Cultivation Factors, Propagation Techniques, and Its Application

Ornamentals come in a variety of shapes, sizes, and colors to suit a wide range of climates, landscapes, and gardening needs. Compared to demand, a shortage of plant materials and diversity force the search for solutions for their constant acquisition and improvement to increase their commercial value, respectively. In vitro cultures are a suitable solution to meet expectations using callus culture, somatic embryogenesis, protoplast culture, and the organogenesis of protocorm-like bodies; many of these techniques are commercially practiced. Factors such as culture media, explants, carbohydrates, plant growth regulators, and light are associated with the success of in vitro propagation. Techniques, especially embryo rescue and somatic hybridization, are widely used to improve ornamentals. The development of synthetic seed allows season-independent seed production and preservation in the long term. Despite the advantages of propagation and the improvement of ornamentals, many barriers still need to be resolved. In contrast to propagation and crop developmental studies, there is also a high scope for molecular studies, especially epigenetic changes caused by plant tissue culture of ornamentals. In this review, we have accumulated and discussed an overall update on cultivation factors, propagation techniques in ornamental plant tissue culture, in vitro plant improvement techniques, and future perspectives.

Improving large-scale biomass and total alkaloid production of Dendrobium nobile Lindl. using a temporary immersion bioreactor system and MeJA elicitation

BACKGROUND

Dendrobium nobile Lindl. is an important pharmacopeial plant with medicinal and ornamental value. This study sought to provide a technical means for the large-scale production of total alkaloid in D. nobile. Seedlings were cultured in vitro using a temporary immersion bioreactor system (TIBS). The four tested immersion frequencies (min/h; 5/2, 5/4, 5/6, and 5/8) influenced the production of biomass and total alkaloid content. In addition, to compare the effects of different concentrations of the phytohormone methyl jasmonate (MeJA) and treatment time on biomass and total alkaloid accumulation, MeJA was added to the TIBS medium after 50 days. Finally, total alkaloid production in semi-solid system (SSS), TIBS, and TIBS combined with the MeJA system (TIBS-MeJA) were compared.

RESULTS

The best immersion frequency was found to be 5/6 (5 min every 6 h), which ensured appropriate levels of biomass and total alkaloid content in plantlets. The alkaloid content and production level of seedlings were the highest after treatment with 10 μM MeJA separately for 20 and 30 days using TIBS. The maximum content (7.41 mg/g DW) and production level (361.24 mg/L) of total alkaloid on use of TIBS-MeJA were 2.32- and 4.69-fold, respectively, higher in terms of content, and 2.07- and 10.49-fold, respectively, higher in terms of production level than those on using of TIBS (3.20 mg/g DW, 174.34 mg/L) and SSS (1.58 mg/g DW, 34.44 mg/L).

CONCLUSIONS

Our results show TIBS-MeJA is suitable for large-scale production of total alkaloid in in vitro seedlings. Therefore, this study provides a technical means for the large-scale production of total alkaloid in D. nobile.

Recent Development in Micropropagation Techniques for Rare Plant Species

The current investigation aimed to present an overview of the conservation of biological diversity of rare and endangered plant species. Methods of biodiversity conservation as well as several overview recommendations for the preservation of various rare species have been considered. An overview of the taxa included in the red book has been presented on the example of the Russian Federation. Global and local codes and classifiers of plant rarity were also presented. Future prospects for the conservation of biological diversity and the creation and development of bioresource collections have been considered.

An Overview of Orchid Protocorm-Like Bodies: Mass Propagation, Biotechnology, Molecular Aspects, and Breeding

The process through induction, proliferation and regeneration of protocorm-like bodies (PLBs) is one of the most advantageous methods for mass propagation of orchids which applied to the world floricultural market. In addition, this method has been used as a tool to identify genes of interest associated with the production of PLBs, and also in breeding techniques that use biotechnology to produce new cultivars, such as to obtain transgenic plants. Most of the molecular studies developed have used model plants as species of Phalaenopsis, and interestingly, despite similarities to somatic embryogenesis, some molecular differences do not yet allow to characterize that PLB induction is in fact a type of somatic embryogenesis. Despite the importance of species for conservation and collection purposes, the flower market is supported by hybrid cultivars, usually polyploid, which makes more detailed molecular evaluations difficult. Studies on the effect of plant growth regulators on induction, proliferation, and regeneration of PLBs are the most numerous. However, studies of other factors and new technologies affecting PLB production such as the use of temporary immersion bioreactors and the use of lighting-emitting diodes have emerged as new tools for advancing the technique with increasing PLB production efficiency. In addition, recent studies on Phalaenopsis equestris genome sequencing have enabled more detailed molecular studies and the molecular characterization of plantlets obtained from this technique currently allow the technique to be evaluated in a more comprehensive way regarding its real applications and main limitations aiming at mass propagation, such as somaclonal variation.

In vitro regeneration from protocorms in Dendrobium aqueum Lindley - An imperiled orchid

An efficient in vitro plant regeneration protocol from protocorms of Dendrobium aqueum was developed. The uniformly developed protocorms (in vitro origin) having shoot initials were cultured on half macro strength MS medium (1/2 MS) supplemented with cytokinins (BA, 2iP, KIN and TDZ) at 1, 3, 5, 7, 10 mg l-1, natural additives (BP and CW) at 1%, 3%, 5%, 7%, 10% and auxins (IBA, NAA, 2,4-D) at 1, 3, 5, 7, 10 mg l-1 to study their efficacy on complete plant development. A maximum of 9.4 shoots per explant were generated on 3 mg l-1 of NAA followed by 3% of BP (7.0 shoots). Shoot elongation (1.52 cm) was achieved on 1/2 MS medium fortified with NAA 7 mg l-1 followed by TDZ 7 mg l-1 (1.37 cm). Shoots cultured on 1/2 MS medium supplemented with IBA 5 mg l-1 produced an average of 8.75 roots per shoot, however the lengthiest roots (1.48 cm) were noted in NAA 7 mg l-1. Healthy rooted plantlets successfully acclimatized in ex vitro condition. The role of complete plantlet production by natural additives could be useful for conservation and cost effective commercial production of orchids.

Dendrobium micropropagation: a review

Dendrobium is one of the largest and most important (ornamentally and medicinally) orchid genera. Tissue culture is now an established method for the effective propagation of members of this genus. This review provides a detailed overview of the Dendrobium micropropagation literature. Through a chronological analysis, aspects such as explant, basal medium, plant growth regulators, culture conditions and final organogenic outcome are chronicled in detail. This review will allow Dendrobium specialists to use the information that has been documented to establish, more efficiently, protocols for their own germplasm and to improve in vitro culture conditions based on the optimized parameters detailed in this review. Not only will this expand the use for mass propagation, but will also allow for the conservation of important germplasm. Information on the in vitro responses of Dendrobium for developing efficient protocols for breeding techniques based on tissue culture, such as polyploidization, somatic hybridization, isolation of mutants and somaclonal variants and for synthetic seed and bioreactor technology, or for genetic transformation, is discussed in this review. This is the first such review on this genus and represents half a decade of literature dedicated to Dendrobium micropropagation.

Genetic stability and phytochemical analysis of the in vitro regenerated plants of Dendrobium nobile Lindl., an endangered medicinal orchid

An efficient genetically stable regeneration protocol with increased phytochemical production has been established for Dendrobium nobile, a highly prized orchid for its economic and medicinal importance. Protocorm like bodies (PLBs) were induced from the pseudostem segments using thidiazuron (TDZ; 1.5 mg/l), by-passing the conventional auxin-cytokinin complement approach for plant regeneration. Although, PLB induction was observed at higher concentrations of TDZ, plantlet regeneration from those PLBs was affected adversely. The best rooting (5.41 roots/shoot) was achieved in MS medium with 1.5 mg/l TDZ and 0.25% activated charcoal. Plantlets were successfully transferred to a greenhouse with a survival rate of 84.3%, exhibiting normal development. Genetic stability of the regenerated plants was investigated using randomly amplified polymorphic DNA (RAPD) and start codon targeted (SCoT) polymorphism markers which detected 97% of genetic fidelity among the regenerants. The PIC values of RAPD and SCoT primers were recorded to be 0.92 and 0.76 and their Rp values ranged between 3.66 and 10, and 4 and 12 respectively. The amplification products of the regenerated plants showed similar banding patterns to that of the mother plant thus demonstrating the homogeneity of the micropropagated plants. A comparative phytochemical analysis among the mother and the micropropagated plants showed a higher yield of secondary metabolites. The regeneration protocol developed in this study provides a basis for ex-situ germplasm conservation and also harnesses the various secondary metabolite compounds of medicinal importance present in D. nobile.

Enhancement of the differentiation of protocorm-like bodies of Dendrobium officinale to shoots by ultrasound treatment

An efficient micropropagation protocol has been developed for Dendrobium officinale, through protocorm-like bodies (PLBs). A correlation between enhanced differentiation of PLBs of D. officinale by ultrasound and changes in the levels of endogenous hormones and the antioxidant enzyme activities was described. Ultrasound treatments improved the conversion of PLBs of D. officinale to shoots. The highest conversion frequency of PLBs to shoots was obtained following the ultrasound treatment at 300 W for 5 min. Compared to the control, the enhanced conversion of PLBs to shoots following the ultrasound treatment was accompanied by an increase in the ratio of total cytokinins (CTKs) to indole-3-acetic acid (IAA), which was due to a decrease in the endogenous level of IAA and an increase in the endogenous level of total CTKs. Analysis of enzyme activities indicated that the increased endogenous level of total CTKs driven by ultrasound was associated with the inhibition of CTK decomposition by CTK oxidase (EC 1.4.3.6), while the decreased endogenous level of IAA was associated with the promotion of IAA decomposition by IAA oxidase (EC 1.10.3.3). In addition, ultrasound treatment increased the activities of superoxide dismutase (EC 1.15.1.1), catalase (EC 1.11.1.6) and peroxidase (EC 1.11.1.7) in the conversion process of PLBs to shoots.