Clarifying the connection between metal exposure and anatomical changes represents an important challenge for a better understanding of plant phytoextraction potential. A hydroponic screening experiment was carried out to evaluate the effects of combined interactions of Cd and Zn on mineral uptake (Mg, K, Ca, Na) and on the physiological and anatomical characteristics of Brassica napus L cv. Cadeli, Viking, and Navajo. Plants were exposed to 5 μM Cd (CdCl), 10 μM Zn (ZnSO), or both Cd + Zn, for 14 days. Cadmium exposure led to a significant reduction in root growth, shoot biomass, and chlorophyll content. After Cd-only and Cd + Zn treatment, primary root tips became thicker and pericycle cells were enlarged compared to the control and Zn-only treatment. No differences between metals were observed under UV excitation, where all treatments showed more intensive autofluorescence connected with lignin/suberin accumulation compared to control conditions. The highest concentrations of Cd and Zn were found in the roots of all tested plants, and translocation factors did not exceed the threshold of 1.0. The root mineral composition was not affected by any treatment. In the shoots, the Mg concentration slightly increased after Cd-only and Cd + Zn treatments, whereas Zn-only treatment caused a sharp decrease in Ca content. Slight increases in K were seen after the addition of Zn. Significantly higher concentrations of Na were induced by Cd- or Zn-only treatment.

No abstract

The effect of methyl jasmonate (MeJA) treatment on diploid and tetraploid plants of Matricaria chamomilla and the changes of the main physiological parameters and secondary metabolites content was studied. Leaf rosettes from 7-week-old plants were harvested at four different time points (24, 48, 72, 96 h) after foliar application of 0.4 mM MeJA. The treatment led to a moderate biomass accumulation accompanied by an accumulation of photosynthetic pigments and decrease in the total soluble proteins. The content of hydrogen peroxide and superoxide radical was most elevated at 24 and 72 h after the treatment. Although the values of stress parameters were higher in tetraploid plants (such as in control so in treated plants), their total increase after the MeJA application was similar. The absolute level of total soluble phenols and flavonoids in the controls was similar in both cultivars and their content was enhanced in 24-and 48-h variants, more rapidly in diploid plants. MeJA has been found to trigger different responses of the secondary metabolites accumulation. Almost all studied metabolites were higher in control plants in the tetraploid cultivar, but their biosynthesis was more stimulated in diploids. Significant changes, mainly increasing trends with a maximum between 24 and 48 h after elicitation, in the content of free coumarin herniarin and its glycosidic precursors (Z)-and (E)-2-b-D-glucopyranosyloxy-4-methoxycinnamic acid were observed. The umbelliferone level increased over time. The maximum values for chlorogenic acid and 1,5-dicaffeoylquinic acid were at 24-h and between the 24-72 h time points. Among dicycloethers, the amounts of (E)-form decreased with time, and for (Z)-form an opposite trend was observed, with a maximum of 96 h for diploid and 24 h for tetraploid after elicitation.

Physiological response of two cultivars of Matricaria chamomilla plants on UV irradiation was studied. The impact of used short-time UV dose was evaluated in three time points; 2, 24 and 48 h after irradiation. Used UV irradiation immediately resulted in changes in plant oxidative status monitored as increased concentration of H2 O2 . Decrease in chlorophyll a and b indicated the impact on photosynthetic apparatus. For phenolic secondary metabolites, an increase in total soluble phenols and AlCl3 -reactive flavonols was observed. The activity of main phenolic enzyme, phenylalanine ammonia-lyase, increased with time after irradiation. Significant changes, mainly decreasing trends, in the content of free coumarins and their glycosidic precursors were observed. Enhanced accumulation in chlorogenic and 1,5-dicaffeoylquinic acid and in (Z)-isoform of dicycloethers was detected. From these results, the redirecting precursors of coumarin biosynthesis to biosynthesis of substances with higher antioxidative potential can be assumed. Different reactions in diploid and tetraploid plants were recorded, too.