Plant growth regulator interactions in physiological processes for controlling plant regeneration and in vitro development of Tulbaghia simmleri.

The endogenous auxin and cytokinin contents of in vitro regenerated Tulbaghia simmleri maintained on applied plant growth regulators in Murashige and Skoog (MS) medium were investigated using UHPLC-MS analysis. The highest number of shoots (27.6 per leaf) were produced in MS medium supplemented with 2.5 µM thidiazuron. A higher number of these shoots were rooted with 10 µM 6-(2-hydroxy-3-methylbenzylamino) purine (PI-55, cytokinin antagonist). Production of somatic embryos (SEs: 16.4-4.6, globular to cotyledonary stages) improved significantly with liquid MS medium containing 2.5 µM picloram, 2.5 µM phloroglucinol (PG) and 1.5 µM gibberellic acid or 1.5 µM PI-55 and 1.0 µM trans-zeatin. SEs (torpedo and cotyledonary stages) germinated (100%) in plant growth regulator free MS medium. The plantlets were acclimatized and all survived in the greenhouse. Higher levels of endogenous auxin, 2-oxindole-3-acetic acid (oxIAA, 371.52 pmol/g DW) and indole-3-acetylaspartate (IAAsp, 141.56 pmol/g DW) were detected in shoots from PG treatments. The roots of garden-grown mother plants possessed the highest level of indole-3-acetic acid (IAA, 630.54 pmol/g DW) and oxIAA (515.26 pmol/g DW). Cytokinins [CKs: trans-zeatin-O-glucoside (tZOG), cis-zeatin (cZ) and N6-isopentenyladenosine-5'-monophosphate (iPRMP)] levels were relatively high in shoots and roots of plantlets in vitro. However, PI-55 treatments influenced the development of plantlets promoting a higher biosynthesis level of iPRMP (418.06 pmol/g DW in root) and cZRMP (904.61 pmol/g DW in roots and 1427.83 pmol/g DW in shoots). The presented protocols offer organogenesis and somatic organogenesis systems for rapid plant regeneration of T. simmleri. In addition, the importance of exogenous and endogenous hormonal effects on in vitro plant growth and development as well as endogenous hormone metabolism signalling and transport related to the physiological processes of CK metabolism and transport are illustrated for in vitro development of T. simmleri.

In vitro propagation via organogenesis and synthetic seeds of Urginea altissima (L.f.) Baker: a threatened medicinal plant.

Efficient in vitro propagation systems via organogenesis and synthetic seeds were developed for the first time for conservation and commercial propagation from leaf or longitudinal thin cell layer (lTCL) leaf or shoot-tip explants of Urginea altissima. Various plant growth regulators and phloroglucinol were used in semi-solid and liquid Murashige and Skoog (MS) medium to establish multiplication of shoots and roots for in vitro regeneration. Of the various treatments, the highest number of shoots (17.4 per lTCL leaf explant) was obtained on liquid MS medium supplemented with 10 µM meta-Topolin (mT) and 2 µM benzyladenine followed by transferal to semi-solid MS media. The shoot tips were encapsulated with liquid MS medium plus 3% (w/v) sodium alginate and 100 mM calcium chloride. Adventitious shoot regeneration (91.0%; 12.6 shoots per synthetic seed) of synthetic seeds was achieved on semi-solid MS medium supplemented with 10 µM mT and 2 µM naphthaleneacetic acid (NAA) after 15 days of storage in darkness at 25 ± 2 °C. Regenerated shoots rooted (9.8 roots per shoot; 6.5 cm long) efficiently when transferred to 5 µM indole-3-butyric acid and 2.5 µM NAA. All the plantlets were successfully acclimatized (100%) in a vermiculite:soil (1:1 v/v) mixture in the greenhouse.

Acetylcholinesterase-Inhibition and Antibacterial Activity of Mondia whitei Adventitious Roots and Ex vitro-Grown Somatic Embryogenic-Biomass.

Mondia whitei (Hook.f.) Skeels is an important endangered medicinal and commercial plant in South Africa. In vitro propagation systems are required for biomass production and bioactivity analysis to supplement wild resources/stocks. Adventitious roots from somatic embryogenic explants using suspension culture and ex vitro-grown plants produced via somatic embryogenesis were established using different plant growth regulator treatments. The adventitious root biomass and different parts of ex vitro-grown and mother plants were used to investigate the potential for acetylcholinesterase (AChE) and antibacterial activities. Adventitious roots derived from 2.5 µM indole-3-acetic acid (IAA) treatments and ex vitro-grown plants derived from meta-topolin riboside and IAA treatments gave the best AChE and antibacterial activities. The in vitro-established M. whitei and ex vitro biomass have comparable ability to function as inhibitors of acetylcholinesterase and antibacterial agents, and can be used as potent bioresources in traditional medicine.

Enhanced HIV-1 Reverse Transcriptase Inhibitory and Antibacterial Properties in Callus of Catha edulis Forsk.

Developing tissue culture systems for medicinal plants is important in that they may offer an alternative to protect wild populations. However, analysis of bioactivity for tissue culture developed plant tissues is required to offer support and allow acceptance in traditional medicine. The use of propagated callus could provide potential material for therapeutic purposes. This study was aimed at evaluating the anti-HIV and antibacterial properties of a three-month-old tissue culture-derived calli and leaves of cultivated mother plants of Catha edulis Forsk. The calli were derived from leaf explants using different plant growth regulators. The calli obtained from callus cultured on 9.8 µM indole-3-butyric acid plus 2.7 µM naphthalene acetic acid exhibited the highest HIV-1 reverse transcriptase inhibitory effects when compared with other treatments and the mother plants. Different extracts of callus exhibited high antibacterial activity (<1 mg/mL: minimum inhibitory concentration from 0.098 to 0.78 mg/mL) against both gram-positive and gram-negative bacteria. Leaf acetone extracts showed moderate activity (minimum inhibitory concentration of 0.78 mg/mL) against Staphylococcus aureus. The present study indicated that tissue culture-derived calli could be used as therapeutic agents for traditional medicine. The choice of treatment used in the tissue culture system and the age of the callus for production of biomass may significantly influence its therapeutic potential.