We studied a stimulatory effect of silver nitrate on callus formation and shoot regeneration of five oilseed rape commercial varieties Ability, Lagonda, Lancia, Menthal and Mirakel (Brassica napus L.). Hypocotyls were induced to organogenesis on the media supplemented with silver nitrate at concentration 5 mg.L1 and without silver nitrate as a control. After 2 weeks of cultivation, calli on the media with silver nitrate became deep green in colour. First shots appeared after 4 weeks of cultivation on the media with silver nitrate. Calli formed on the control media were pale green and did not form any shoots or at very low efficiency. Silver nitrate improved regeneration efficiency from 0- 0.8% to 8.3-10% in varieties Albina, Lancia and Menthal. Explants of Lagonda and Mirakel did not form any calli and these varieties appeared to be recalcitrant. Analyses of six weeks-old calli showed that silver nitrate increased concentration of photosynthetic pigments, which is a good prerequisite for cell regeneration. Silver nitrate increased malondialdehyde level and induced changes in enzyme activities of antioxidants ascorbate peroxidase and catalase; and in the accumulation of non-enzymatic antioxidant proline; in the genotype dependant manner. The results suggest that an activation of stress response was necessary to obtain shoots with higher frequency in the varieties Albina, Lancia and Menthal.

A solid-phase extraction (SPE) procedure was developed for simultaneous monitoring of sixteen different phenolics of various polarity, quantified by high-performance liquid chromatography (HPLC). The procedure allowed screening the accumulation of intermediates in different metabolic pathways that play a crucial role in plant physiology and/or are beneficial for human health. Metabolites mostly involved in phenylpropanoid, shikimate, and polyketide pathways comprise chlorogenic acid, gentisic acid, vanillic acid, caffeic acid, protocatechuic acid, ferulic acid, rutin, quercetin, epicatechin, gallic acid, sinapic acid, p-coumaric acid, o-coumaric acid, vanillin; two rarely quantified metabolites, 2,5-dimethoxybenzoic acid and 4-methoxycinnamic acid, were included as well. The procedure offered low cost, good overall efficiency, and applicability in laboratories with standard laboratory equipment. SPE recoveries were up to 99.8% at various concentration levels. The method allowed for routine analysis of compounds with a wide range of polarity within a single run, while its applicability was demonstrated for various model plant species (tobacco, wheat, and soybean), as well as different tissue types (shoots and roots).

Given the potential use of flax in metal-contaminated soil remediation programs, the uptake and accumulation of cadmium was studied in five varieties of flax (Linum usitatissimum L.) including var. Belinka, Escalina, Jitka, Marina and Krasnoder. Early stage plants in hydroponics were exposed to Cd to assess their tolerance by means of growth parameters and content of photosynthetic pigments. All varieties exerted tolerance indexes in the range of 63 – 89 %, while oxidative stress was not detected in either variety. Chitinase enzymes were analyzed in leaf protein extracts since activities of these enzymes have previously been correlated with plant tolerance to Cd. However, total enzyme activities remained unchanged in presence of Cd in all flax varieties. A more detailed analysis of these enzymes identified up to 3 chitinase isoforms upon separation of leaf protein extracts in polyacrylamide gels, and their quantification confirmed responsiveness to Cd for each of them. The obtained data were interpreted in light of metal uptake rate, which we measured using gammaspectrometry in growth media spiked with 109Cd and in the plant tissue. The variety Jitka showed the most sensitive to Cd and accumulating fast and the highest amounts of metal. In contrast, the variety Belinka appeared most tolerant, accumulating the least Cd in a slow rate. Activation of chitinase isoforms correlated with more sensitive varieties and suggests activation of general defense mechanisms. The obtained data suggest the variety Jitka as most promising for phytoremediation programs and the var. Belinka as the most suitable when avoidance of potential health risk is of interest.