Explore the vast range of titles available.

This study highlights the development and achievements made for the micropropagation of Greek oregano (Origanum heracleoticum L. ) using stem tip explants. The shoots were cultured on Murashige and Skoog (MS) medium followed different concentrations of plant growth regulators (PGR) - 6-benzyl aminopurine, thidiazuron and zeatin at concentrations (0.5 or 1.0 mg L-1). The induction of multiple shoots from stem tip segments was the highest in MS medium supplemented with 1.0 mg L-1 zeatin. It was the most effective medium for shoot formation, which produced multiple shoots (2.7) with an average height of 3.5 cm. These shoots were transferred on half strength MS medium containing three different auxins: indole-3-butyric acid, α-naphthalene acetic acid or indole-3-acetic acid (0, 0.1 and 0.5 mg L-1) for rooting, Multiple shoots were the most efficiently rooted on ½ MS medium supplemented with 0.5 mg L-1indole-3-butyric acid. Rooted plants showed the best adaptation on pots containing peat: perlite (2: 1 v/v). The higher rates of shoots number and height per plant have a positive relationship with the production of metabolites with antioxidant potential as phenols and flavonoids as well as with ferric reducing antioxidant potential.

The effect of inoculation with arbuscular mycorrhizal fungi Claroideoglomus claroideum on Coleus forskohlii (Willd.) Briq. plants propagated by seeds or in vitro, and subsequently exposed to drought stress has been studied. Stress tolerance and yield stability are closely related to coping with oxidative stress, which occurs at prolonged water deprivation.The plants inoculated with Claroideoglomus claroideum were grown in well-watered and drought-stressed conditions. The parameters of the inoculation with arbuscular mycorrhizal fungi (root colonization, total and easy-extractable-glomalin-related soil proteins, acid and alkaline phosphatases in roots and soil) and antioxidant activity (enzyme and non-enzyme parameters) were evaluated. In the inoculation of in vitro and in vivo propagated Coleus forskohlii (Willd.) Briq.with arbuscular mycorrizal fungi (AMF), an increase in the growth parameters, the activity of enzymes with antioxidant capacity and the content of total phenols and flavonoids and water- and lipid-soluble metabolites with antioxidant capacity were recorded compared with non inoculated plants. The results showed that arbuscular mycorrhizal fungi Claroideoglomus claroideum activate plants’ antioxidant system, leading to reduced oxidative stress damage. The reduction in oxidative stress markers (hydrogen peroxide, malondialdehyde and proline) content as a result of AMF inoculation was higher in adapted in vitro propagated plants compared to in vivo plants. The same trend is observed in drought stressed plants. When grown in water-deficient conditions, adapted micro-propagated plants showed higher plant growth parameters such as shoot height, root length, plant biomass, antioxidant activity, and lower levels of oxidative stress markers, suggesting that they are more resistant to drought than the individuals which were grown from seeds.

Arnica montana L. is an endangered species rich in sesquiterpene lactones, phenolic acids and flavonoids with high pharmaceutical value. The polyphenolic content and free radical scavenging activity of plants that had passed all stages of cultivation: micropropagation and rooting (in vitro), adaptation in greenhouse (ex vitro) and mountain conditions (in vivo) were evaluated. Four surface flavonoid aglycones [scutellarein 6-methyl ether (hispidulin), scutellarein 6,4’-dimethyl ether (pectolinarigenin), 6-OH luteolin 6-methyl ether and kempferol-6-methyl ether] were detected in the acetone exudates of the studied samples bymeans of thin layer chromatography.No differences in the accumulation of surface flavonoids were found among the tested leaf extracts of in vitro, ex vitro and in vivo samples. However, the extracts from the flowers were richer in surface flavonoids than extracts from the leaves. The methanol extracts of the samples from ex vitro and in vivo grown A. montana plants had significantly higher radical scavenging activity and polyphenolic content than the extracts of in vitro samples. The observed differences in the contents of these biologically active compounds were related to different growth conditions and stages of plant development. The biotechnological method of A. montana established holds promise for the future production of antioxidants.

Arnica montana L. (Asteraceae) is a valuable medicinal plant with anti-inflammatory and cicatrizing properties attributed to the sesquiterpene lactones, flavonoids and essential oil produced in the flower heads. In many European countries, the populations of A. montana are close to extinction in their natural habitats because of uncontrolled eradication and indiscriminate collection of the plants. Various approaches for in vitro propagation of the species and also, biosynthesis of secondary metabolites in tissue and cell cultures are assessed in the current review. Special attention is paid to the biological activity and chemical composition of compounds produced by the species as well as the opportunities of in vitro methods to isolate high-productive clones. The influence of different factors on the micropropagation, callusogenesis, genetic transformation and identification of certain biologically active substances is discussed in detail. By the reference to the available issues we concluded that biotechnology applied to A. montana cultivation may improved the plant preservation and increased the production of sesquiterpene lactones and other secondary metabolites.