In vitro Propagation of Vanda testacea (Lindl.) Reichb. F, a Medicinally Important Threatened Orchid

The present study was planned to enable in vitro conservation of Vanda testacea, a highly medicinal orchid species through in vitro asymbiotic seed germination technique in Mitra orchid medium supplemented with cytokinins (Kn - 4.65 μM, BAP - 4.44 μM), and auxin (NAA- 5.37 μM). The germination frequency and initiation of germination was higher in NAA augmented medium and seedlings developed in 12.50 ± 0.50 weeks. Coconut water (20%) proved optimum for the multiplication of protocorm like bodies. Activated charcoal successfully checked the release of brownish exudates in the cultures. Plant Tissue Cult. & Biotech. 31(2): 153-160, 2021 (December)

Orchids as Valuable Folklore Medicine: A Review

The impetus of writing this paper is to review various medicinal orchid species growing in different parts of India. The family orchidaceae is one of the diverse groups among angiosperms which includes different types of orchid species. This paper is written to review the medicinal and therapeutic importance and use of different orchid species for treatment of various types of diseases. Orchids are herbaceous plants which are mentioned in ancient ayurvedic system of medicine because of their therapeutic properties. Most of the medicinal orchid species are epiphytic and terrestrial in habitat.

Six-Year Demographic Study of the Terrestrial Orchid, Crepidium acuminatum: Implications for Conservation

Studies on population dynamics are helpful for understanding the factors determining population development and predicting the effects of disturbances, such as harvesting of plant species. In an investigation of the demography of a terrestrial medicinal orchid known as Crepidium acuminatum, the effects of harvesting on its population dynamics were recorded. Data on recruitment, growth and survival were collected in three populations of C. acuminatum over a 6-year period (2012–2017) in central Nepal. A matrix modeling method was used to determine the effect of different harvesting regimes on the population growth and survival of this species. Population growth rates (λ) of unharvested populations were relatively similar and stable in different years of the study. Harvesting significantly reduced λ. The results of this study indicate that the sustainable survival of a population that is subject to harvesting can only occur when it is either selective (only flowering individuals or only small amounts of vegetative individuals) or rotational (once every 3–5 or more years). This study demonstrates the necessity of using a sustainable method when harvesting natural populations. Our results are useful for developing efficient management strategies for this species. As each species has a different biology, similar studies are needed for other rare and/or economically important species in the Himalayan region and in other understudied parts of the world.

Chromosome-scale assembly of the Dendrobium chrysotoxum genome enhances the understanding of orchid evolution

As one of the largest families of angiosperms, the Orchidaceae family is diverse. Dendrobium represents the second largest genus of the Orchidaceae. However, an assembled high-quality genome of species in this genus is lacking. Here, we report a chromosome-scale reference genome of Dendrobium chrysotoxum, an important ornamental and medicinal orchid species. The assembled genome size of D. chrysotoxum was 1.37 Gb, with a contig N50 value of 1.54 Mb. Of the sequences, 95.75% were anchored to 19 pseudochromosomes. There were 30,044 genes predicted in the D. chrysotoxum genome. Two whole-genome polyploidization events occurred in D. chrysotoxum. In terms of the second event, whole-genome duplication (WGD) was also found to have occurred in other Orchidaceae members, which diverged mainly via gene loss immediately after the WGD event occurred; the first duplication was found to have occurred in most monocots (tau event). We identified sugar transporter (SWEET) gene family expansion, which might be related to the abundant medicinal compounds and fleshy stems of D. chrysotoxum. MADS-box genes were identified in D. chrysotoxum, as well as members of TPS and Hsp90 gene families, which are associated with resistance, which may contribute to the adaptive evolution of orchids. We also investigated the interplay among carotenoid, ABA, and ethylene biosynthesis in D. chrysotoxum to elucidate the regulatory mechanisms of the short flowering period of orchids with yellow flowers. The reference D. chrysotoxum genome will provide important insights for further research on medicinal active ingredients and breeding and enhances the understanding of orchid evolution.

Quantitative Phytochemical Analysis Reveals Significant Antibiofilm Activity in Pleione maculata, an Endangered Medicinal Orchid

Pleione maculata has no scientific reports on quantitative phytochemical and antibiofilm activity till date. The objective of the study was to quantify and determine medicinally important bioactivity in P. maculata and analyse its anti-biofilm activity against clinical isolates Staphyloccocus aureus, Klebsiella pneumoniae and Proteus mirabilis. P. maculata exhibited the highest Total Antioxidant Capacity (TAC) about 193.98 ± 0.1 mg, highest Total Phenolic Content (TPC) at 552± 0.0 mg and Total Flavonoid Content (TFC) were observed highest at 879.5 ± 0.2 mg. The acetone and ethyl acetate extracts of P. maculata pseudobulb showed distinct and significant zone of inhibition (ZOI) against drug-resistant S.aureus about 16 ± 0.00 mm (MIC 0.875 mg/mL), ZOI of acetonitrile pseudobulb extract against P. mirabilis was 15.33 ± 0.4mm (MIC 1 mg/mL), ZOI of acetonitrile extracts of leaves and stem, ethyl acetate extract of pseudobulb was 12 ± 0.0mm, 12 ± 01.4mm, 12 ± 2.8mm against K. pneumoniae (MIC 1.8 mg/mL, 0.68 mg/mL and 3 mg/mL). Acetonitrile extract of pseudobulbs exhibited the highest Minimum Biofilm Inhibition concentration (MBIC) at 0.25 mg/mL against S. aureus, water root extract inhibited attachment of K. pneumoniae with lowest MBIC value 0.093 mg/mL, water and acetone extract of leaves inhibited cell attachment of P. mirabilis at lowest MBIC 0.117 and 0.171 mg/mL. The UV-VIS absorption band of P. maculata extracts ranges from 204-665 nm indicating the presence of phenolic and flavonoid compounds. The study indicates the potentiality of P. maculata as a rich source of medicinal active compounds as an antibiofilm agent against antibiotic-resistant clinical isolates.

Plantlet Regeneration and Multiple Shoot Induction from Protocorm-Like Bodies (PLBs) of Medicinal Orchid Species, Dendrobium crumenatum Sw.

To investigate the suitable medium for in vitro shoot regeneration and plantlet growth of Dendrobium crumenatum Sw., individual protocorm-like bodies (PLBs) (about 4 - 5 mm in diameter) of Dendrobium crumenatum Sw. derived from MS medium supplemented with 0.5 mg/L TDZ for 60 days of culture were cultured on 6 culture media; Murashige and Skoog (MS) medium, MS medium supplemented with 15 % (v/v) CW, MS medium supplemented with 15 % (v/v) CW and 0.2 % (w/v) AC, Vacin and Went (VW) medium, VW medium supplemented with 15 % (v/v) CW, VW medium supplemented with 15 % (v/v) CW and 0.2 % (w/v) AC. After 4 months of culture, MS medium containing 15 % coconut water (CW) gave the highest percentage of shooting and number of shoots per explant of 96.0 and 9.5, respectively with a significant difference from other media. The addition of 0.2 % (w/v) activated charcoal (AC) significantly increased the number of leaves and roots. PLBs developed into complete plantlets. MS medium supplemented with 15 % (v/v) CW and 0.2 % (w/v) AC and VW medium supplemented with 15 % (v/v) CW and 0.2 % (w/v) AC gave the highest number of roots per plantlet and root length at 5.3 roots and 34.9 mm, respectively. After the transfer of rooted shoots to the greenhouse, 95 % of the regenerated plantlets survived and grew vigorously. Plantlets grown in vitro were successfully acclimatized in the greenhouse and showed normal development.