M. V. Rao

In vitro propagation of Ceropegia thwaitesii Hook- an endemic species of Western Ghats of Tamil Nadu, India

In vitro propagation of Ceropegia thwaitesii Hook (Asclepiadaceae), an endemic plant species of Western Ghats, Tamil Nadu (India), was carried out. Auxiliary bud explants were cultured on Murashige and Skoog (MS) medium fortified with cytokinins (KIN), 6-benzyl adenine (BA), 2-isopentenyladenine (2-iP) and thidiazuron (TDZ) in various concentrations and in combination with auxins indole-3-butyric acid (IBA), indole-3-acetic acid (IAA) and naphthalene acetic acid (NAA). High frequency of shoot bud proliferation and multiplication was observed on KIN (13.94 μm) + IAA (28.54 μm). Rhizogenesis was observed on MS medium supplemented with IBA 2.46 μm and plantlets produced through micropropagation were hardened with the survival success of 73.33%. The efficient Micropropagation regeneration protocol developed would aid ex situ conservation of this endemic species. Key words : Ceropegia thwaitesii , in vitro propagation, Asclepiadaceae, plant growth regulators, micropropagation.

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.

Antimicrobial, antioxidant and anticancer activity of biogenic silver nanoparticles – an experimental report

In the present study, use of a Helicteres isora stem bark extract for the biosynthesis of AgNPs is described. It was observed that the aqueous silver (Ag+) ions, once associated in the stem bark extract, were reduced in solution, thereby leading to formation of the stable AgNPs. These AgNPs were characterized using several techniques. The nanoparticles show a maximum absorbance at 419–431 nm in the ultraviolet-visible spectra. The presence of the steroid sapogenin was identified using Fourier transform-infrared (FTIR) spectroscopy. The reduction of the Ag+ ions to elemental silver was investigated by using X-ray diffraction (XRD). Transmission electron microscopy (TEM) revealed the formation of monodisperse, with low polydispersity, nanoparticles of 25.55 nm, and the presence of elemental silver was confirmed through energy dispersive spectroscopy (EDX) analysis. The AgNPs showed antioxidant activities such as DPPH, hydrogen peroxide and nitric oxide radical scavenging and a reducing power compared to the standard compounds. The antibacterial effect was determined against test strains, showing significant inhibition. The antiproliferative activity of the AgNPs was demonstrated using oral carcinoma (KB) cells with MTT, and confirmed using AO/EtBr, comet assay, DCFH-DA and Rhodamine 123 staining. In the toxicity study, a significant mortality rate was observed against Artemia with an IC50 concentration of 70 μg mL−1 and 108 h exposure. The NPs showed as cytotoxic against Artemia at 108 h, so they are cytotoxic at high concentrations and after prolonged exposure.

Influence of nutritional media and photoperiods on in vitro asymbiotic seed germination and seedling development of Dendrobium aqueum Lindley

1 /2 MS medium (93.41%) followed by mMS (91.04%) and m ½ MS (90.23%) in 6 to 7 weeks. The biggest protocorms were observed in MS medium (788.8 µm) followed by ½ MS (615.60 µm). The yellowish embryos during germination exhibit varied colours from yellow to pale green, dark green, yellow, brown, black and white. MS, ½ MS, mMS, ½ mMS, and ¼ MS media only promote fully developed seedlings within 126 to 143 days. The influence of five different photoperiods with four media was also examined separately. 24/0 hrs (L/D) photoperiod provide highest germination (97.75%) on MS followed by ½ MS (96.01%). Dark Photoperiod 0/24 h (L/D) supports up to protocorm stage but with poor seedling growth. The well rooted seedlings were hardened and successfully reintroduced in its natural habitat with 56% survival rate.

Effects of Different Media and Organic Additives on Seed Germination of Geodorum Densiflorum (Lam) Schltr. – An Endangered Orchid

Interaction of different media and organic additives showed significant effects on seed germination of G. densiflorum. Among the different organic additives tomato extracts significantly enhanced seed germination and was found to be the most suitable one for enhance the seed germination, It was also the best among treatments for production of viable protocorms. Highest seed germination was recorded in 5% tomato extract fortified with 1⁄2 MS medium than compared to mMS, MS, KC medium. In this study, Tomato was selected to be the best organic additive and 1⁄2 MS medium as the suitable medium for seed germination of G.densiflorum when compared to other organic additives like potato and coconut water and different media. Effects of Different Media and Organic Additives on Seed Germination of Geodorum Densiflorum (Lam) Schltr. – An Endangered Orchid

In Vitro Studies, Biosynthesis of Secondary Metabolites and Pharmacological Utility of Catharanthus roseus (L.) G. Don.: A Review

Catharanthus roseus (L.) G. Don (formerly Vinca rosea L.) belongs to the family Apocynaceae, it has been used to control cancer, diabetes, malaria etc., by folklore and traditional medicinal herbalists of India over two millennia. It is one of the most studied legendary medicinal plants due to the presence of monoterpene indole alkaloids (MIAs) or terpenoid indole alkaloids (TIAs). The active constituents from above ground parts extract contain most well recognized invaluable anticancer drugs vinblastine and vincristine, some antifibrillic and hypertensive agents, whereas the root contains several bioactive drugs such as, ruabasine (ajmalicine), serpentine, vinceine, vincamine and reserpine. In this review, the botanical information, ethnobotanical significance, update in tissue culture, secondary metabolites biosynthesis, cellular compartmentation and their pharmacological properties discovered and proved in the past decades and their potential in further exploitation of C. roseus are discussed.

Non-deep simple morphophysiological dormancy in seeds of the rare Alpinia galanga : a first report for Zingiberaceae

Little information is available on seed dormancy of members of the Zingiberales and especially the Zingiberaceae. Our aim was to investigate the dormancy breaking and germination requirements of Alpinia galanga in vitro with a minimum number of seeds, using the move-along experiment. The mass of imbibed seeds increased by 17.5% in 1 d, showing that seeds were water permeable. The best germination in the move-along experiment (86.7%) was obtained when seeds were exposed to the sequence of temperature regimes that began with winter (20/10°C), and seeds began to germinate after 6 weeks at this temperature regime. Seeds dry stored for 4 months and then incubated at the sequence of temperature regimes that began with summer (30/20°C) started germinating in the sixth week at this temperature regime and had germinated to 93.3% after 18 weeks. Seeds kept dry for 4 months and then treated with 50 mg l −1 gibberellic acid (GA 3 ) began to germinate at 30/20°C after 2 weeks. Control seeds incubated continuously at 20/10, 25/15 or 30/20°C germinated to 80.6, 77.8 and 60.0%, respectively. When incubated at 15, 20, 25 or 30°C, the ideal temperature for embryo growth was 20°C. Since GA 3 and dry storage can break non-deep physiological dormancy and embryos grew during warm stratification, seeds of A. galanga have non-deep simple morphophysiological dormancy (MPD). This is the first report of non-deep simple MPD in the Zingiberaceae.

Phytochemical analysis, antioxidant and antimicrobial activity of wild and in vitro derived plants of Ceropegia thwaitesii Hook – An endemic species from Western Ghats, India

Ceropegia thwaitesii Hook (Asclepiadaceae), an endemic plant species, due to habitat destruction and over exploitation has a very restricted distribution in the Western Ghats of Tamil Nadu, India. The present wrok aimed to determine the chemical composition, the total phenolic (TPC), flavonoid (TFC) and tannin content (TEC), and to assess the antioxidant properties of various extracts of in vivo plants (IVP) and in vitro regenerated plants (IRP) of C. thwaitesii. Some phenolic compounds like gallic acid, cathechol, vanillin and salicylic acid were identified and quantified by HPLC. All the extracts possessed relevant radical scavenging activity on DPPH, Superoxide radical scavenging activity, and Nitric oxide radicals as well as total antioxidant ability. DPPH assay of in vitro methanol stems extracts and ethanol leaves extracts revealed the best antioxidant properties with important IC50 values of 0.248 ± 0.45 µg/mL and 0.397 ± 0.67 µg/mL, respectively, whereas in vivo chloroform stems extracts showed a lower antioxidant activity (IC50 of 10.99 ± 0.24 µg/mL). The IRP methanol extracts of stem and leaves had good inhibitory activity against all tested microorganisms in a dose-dependent manner. These results suggested that in vitro raised plants of C. thwaitesii are an excellent source of antioxidant compounds to be exploited on an industrial level as food additive.

Effect of Plant Growth Regulators and Additives on Indirect Organogenesis of Simarouba glauca DC

A protocol of in vitro propagation of Simarouba glauca DC (Simaroubaceae) by indirect organogenesis under the influence of different combinations of plant growth regulators (PGRs) was standardized. Indole-3-butyric acid 1.0 mg/l produced the highest callusing response: 100 % in cotyledon and 95 % in internode explant. One hundred percent of shoot bud induction response with shoot number 18.0 for cotyledon and 85 % response of shoot bud induction with shoot number 12.5 for internode were observed in 6-benzyl adenine (BA) 3.0 mg/l, 6-furfuryl amino purine 0.5 mg/l, and GA31.0 mg/l. Organic additive coconut water that resulted in 95 % response with average 25.0 shoot number for cotyledon and 80 % response with average shoot number of 18.2 for internode was observed in the medium containing CW (15 %). GA3 promoted only shoot multiplication with no shoot elongation. High concentration of GA3 directly involved in shoot elongation rather multiplication, but it caused some irreversible root inhibition. α-Naphthalene acetic acid 2.0 mg/l showed 95 % and 80 % of rooting response with root numbers 8.5 and 7.2 in cotyledon and internode explants, respectively. The microshoots with the lengthy roots were transferred to paper cups for acclimatization. After a period of 12 weeks, acclimatized plants were successfully transferred to the field. The 56.8 % plants survived in the field.

In Vitro Plant Regeneration in Dainty Spur [ Rhinacanthus nasutus (L.) Kurz.] by Organogenesis

A proficient organogenesis protocol was standardised for Rhinacanthus nasutus, a potential medicinal plant. MS medium supplemented with NAA (2.0 mg/l) + ascorbic acid (30 mg/l) was found to be more effective for callus induction. The highest number of 140.7 shoots/explant with shoot length of 15.5 cm from the callus derived from internode explant and 122.3 shoots/explant with shoot length of 11.0 cm from leaf explant-derived callus were observed on MS medium containing 2.0 mg/l BA + 2.0 mg/l KN + 2.0 mg/l NAA. IAA (1.0 mg/l) has showed effective rooting.