In Vitro Cultures of Some Medicinal Plant Species (Cistus × incanus, Verbena officinalis, Scutellaria lateriflora, and Scutellaria baicalensis) as a Rich Potential Source of Antioxidants-Evaluation by CUPRAC and QUENCHER-CUPRAC Assays

Comparative estimations of the antioxidant activity of methanolic extracts from biomasses of different types of in vitro cultures of Cistus × incanus, Verbena officinalis, Scutellaria lateriflora, and S. baicalensis and also from plant raw materials were performed. The antioxidant measurements were based on the modern assays-cupric ion reducing antioxidant capacity (CUPRAC) and quick, easy, new, cheap, and reproducible CUPRAC (QUENCHER-CUPRAC). The total extractable antioxidants (CUPRAC assay) ranged from 10.4 to 49.7 mmol (100 g)^-1 of dry weight (DW) expressed as Trolox equivalent antioxidant capacity (TEAC), and the global antioxidant response (QUENCHER-CUPRAC assay) ranged from 16.0 to 79.1 mmol (100 g)^-1 DW for in vitro cultures, whereas for plant raw materials the total extractable antioxidants ranged from 20.9 to 69.5 mmol (100 g)^-1 DW, and the global antioxidant response ranged from 67.2 to 97.8 mmol (100 g)^-1 DW. Finally, the in vitro cultures could be regarded as an antioxidant-rich alternative resource for the pharmaceutical, health food and cosmetics industries.

The role of chloroplasts in the oxidative stress that is induced by zearalenone in wheat plants - The functions of 24-epibrassinolide and selenium in the protective mechanisms

This study focused on the idea that the toxic effect of zearalenone (ZEA) and the protective actions of the brassinosteroid - 24-epibrassinolide (EBR) as well as selenium are dependent on its accumulation in chloroplasts to a high degree. These organelles were isolated from the leaves of oxidative stress-sensitive and stress-tolerant wheat cultivars that had been grown from grains that had been incubated in a solution of ZEA (30 μM), Na₂SeO₄ (Se, 10 μM), EBR (0.1 μM) or in a mixture of ZEA with Se or EBR. Ultra-high performance liquid chromatography techniques indicated that ZEA was adsorbed in higher amounts in the chloroplasts in the sensitive rather than tolerant cultivar. Although the brassinosteroids and Se were also accumulated in the chloroplasts, higher levels were only found in the tolerant cultivar. The application of EBR increased the homocastasterone content, especially in the chloroplasts of the tolerant plant and after the addition of ZEA. The presence of both protectants caused a decrease in the ZEA content in studied organelles and resulted in diminishing of the oxidative stress (i.e. changes in the activity of the antioxidative enzymes). Moreover, a recovery of photosystem II and decrease in the negative impact of ZEN on Hsp90 transcript accumulation was observed in plants.

The Influence of Growth Regulators on Membrane Permeability in Cultures of Winter Wheat Cells

The effect of plant growth substances (IAA, 2,4-D, zeatin, kinetin, zearalenone) were studied on membrane properties of the cells of embryogenic (E) and non-embryogenic (NE) calli derived from immature inflorescences (inf) or embryos (emb) of winter wheat. Calli initiated from inflorescences show higher permeability. The ion leakage from cells of E calli was higher than from cells of NE calli. Growth regulators were used in concentrations of 2-30 mg/l (about 10-140 μm). All tested growth substances increased ion leakage from NE emb cells, IAA, zeatin and kinetin being most effective. In NE inf cells the effect of growth substances was similar as in NE emb, but much weaker. In E cells of both types (inf and emb) growth substances decreased ion leakage. Changes in the leakage of potassium and calcium ions were similar to those in total ion leakage. The uptake of labelled auxins (IAA and 2,4-D) was higher in NE cells (especially in NE inf) than in E cells. The endogenous level of IAA was higher in E cells than in NE cells and in inf cells than in emb cells. The importance of auxin in determining permeability of cell membranes is discussed.

Cytokinins in shoot apices of Brassica napus plants during vernalization

The putative role of cytokinins in processes leading to reproductive development of plants was investigated by analysing the shoot apical parts of a winter cultivar of oilseed rape (Brassica napus L. var. oleifera, cv. Górczański). The endogenous cytokinin levels were measured by liquid chromatography-tandem mass spectrometry (LC-MS) in the shoot apices of vegetative plants (grown at 20/17°C with a 16/8h day/night regime) and vernalized plants (56 days at 5/2°C with a 16/8h photoperiod) at different times during floral transition. During vernalization, the content of all isoprenoid cytokinins increased significantly, coinciding well with the onset of the early stages of reproductive development. Cytokinin levels reached their maxima when most of the plants became irreversibly reproductive (after 42 days of cold treatment). cis-Zeatin riboside (unequivocally identified by quadrupole-time-of-flight MS) accounted for ca. 87-89% of the total isoprenoid cytokinin content in control and vernalized plants, whilst N(6)-isopentenyladenosine ( approximately 6% in control and approximately 8% in vernalized plants) and cis-zeatin (approxiamtely 2% in control and approximately 1% in vernalized plants) were the next most abundant cytokinins. In the post-vernalization period, endogenous cytokinin levels decreased, but remained significantly higher in the reproductive plants than in the vegetative controls. These results suggest that cytokinins, especially those of the cis-zeatin type, are involved in vernalization-induced reproductive development of B. napus.

Cytokinin activities in cells of wheat inflorescence in depependence of its developmental stage

We demonstrate that differences in the endogenous biologically active levels and patterns of cytokinins depend on the organ differentiation, i. e. immature inflorescence before meiosis and immature embryo 14 days after anthesis, respectively, in winter wheat of two genotypes: Grana and Almari. Two cell lines were subjected to analysis of cytokinin contents. Higher levels of endogenous cytokinin were found in cells derived from immature embryo (E) in comparison to cells obtained from immature inflorescence (I). The levels of zeatin ryboside ([9R]Z) and benzyladenosine ([9R]BAP) were predominant and isopentenyladenine (iP) was very low for the cells E of both genotypes. The cytokinin amounts in cells E and I of the zeatin group were smaller than those of other groups. We suggest that the concentration of cytokinins in tissue capable of generative development in winter wheat should be on a level that occurred in inflorescence cell lines, in comparison to immature embryo cell lines. These results indicate that the effect of the developmental stage of ears of wheat on the capability to flower in winter wheat plants regenerated in in vitro culture may be induced by the hormone level.