Influence of salicylic acid pretreatment on seeds germination and some defence mechanisms of Zea mays plants under copper stress.

The study was focused on the influence of salicylic acid (SA) on maize seeds germination and on some physiological and biochemical processes in maize plants growing in the hydroponic culture under copper (Cu) stress. A significant influence of SA pretreatment on the advanced induction of the maize seeds metabolic activity and the level of the endogenous SA in germinated seeds and developing roots have been stated. Although, the ability of maize seeds to uptake SA and accumulate it in the germinated roots was confirmed, the growth inhibition of Cu-stressed maize seedlings was not ameliorated by SA seeds pretreatment. Cu-stressed plants exhibited a decrease in the photosynthetic pigment concentration and the increase in non-photochemical quenching (NPQ) - an indicator of an excess energy in PSII antenna assemblies lost as a heat. The amelioration effect of SA application was found only for carotenoids content which increased in stressed plants. It was also shown that maize roots growing in stress conditions significantly differed in the chemical composition in comparison to the roots of control plants, but the SA pretreatment did not affect these differences. On the other hand, it was found that SA seed pretreatment significantly influenced the ability of stressed plants to accumulate copper in the roots. It was stated that a higher level of exogenous SA application led to a lower accumulation of Cu ions in maize roots. Cu-stressed plants exhibited higher oxidative stress in roots than in leaves which was manifested as an increase in the concentration of hydrogen peroxide due to stress factor application. We observed an increase in catalase (CAT) activity in leaves of Cu-stressed plants which corresponded with a lower H2O2 content when compared with roots where the hydrogen peroxide level was higher, and the inhibition of the CAT activity was found. Furthermore, we found that the SA seed pretreatment led to a decrease in the H2O2 content in the roots of the Cu-stressed plants, but it did not influence the H2O2 level in leaves. The increase in hydrogen peroxide content in the roots of Cu-stressed plants correlated with a higher activity of the MnSODI and MnSODII isoforms. It was found that SA pretreatment caused a decrease in MnSODII activity accompanied by the decrease in H2O2 concentration. Achieved results indicated also that the changes in the chemical composition of the root tissue under copper stress constituted protection mechanisms of blocking copper flow into other plant organs. However, it might be assumed that the root tissue remodelling under Cu stress did not only prevent against the Cu ions uptake but also limited the absorption of minerals required for the normal growth leading to the inhibition of the plant development.

Effects of Cd and Zn on physiological and anatomical properties of hydroponically grown Brassica napus plants.

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 (CdCl2), 10 µM Zn (ZnSO4), 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.

Azorella compacta Infusion Activates Human Immune Cells and Scavenges Free Radicals In vitro.

BACKGROUND: Azorella compacta is traditionally used in the form of tea (infusion), in the Andean region of South America, to treat various chronic diseases. However, the health-promoting properties of this herbal tea have not yet been extensively explored. MATERIALS AND METHODS: The free radical scavenging activity of A. compacta infusion (ACI) was evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical and superoxide anion radical assays. The activation of immune cells by ACI, as determined by cell surface cluster of differentiation 69 expression, was measured by flow cytometry. The qualitative polyphenolic composition of ACI was investigated by HPLC/PDA/ESI-MS, (High-performance liquid chromatography coupled with photodiode array detection and electrospray ionization - mass spectrometry) and the total content of polyphenols was estimated by spectrophotometric methods. RESULTS: Eight polyphenols including chlorogenic acid, 6,8-di-C-hexosyl apigenin, isoorientin, orientin, dicaffeoylquinic acid, biochanin A-O-glucoside, biochanin A-O-(malonyl)-glucoside, and licoisoflavone A were tentatively identified in ACI. The total contents of phenols, flavonoids, and tannins in lyophilized ACI were 5.40 mg/100 mg ACI, 1.79 mg/100 mg ACI, and 1.76 mg/100 mg ACI, respectively. ACI, within the range of 25-400 µg/mL, scavenged DPPH and O2.- by 15-90% and 20-88%, respectively. The human natural killer (NK) cells were substantially activated by ACI, whereas T cells and granulocytes were slightly stimulated. CONCLUSION: Overall, the results demonstrate the free radical scavenging and immune-stimulating properties of ACI, and support, at least in part, its potential utilization as a functional herbal tea. for preventing chronic diseases and as a nonspecific immune stimulator during human immunosenescence. SUMMARY: The total contents of phenols, flavonoids, and tannins in Azorella compacta infusion (ACI) were 5.40 mg/100 mg ACI, 1.79 mg/100 mg ACI, and 1.76 mg/100 mg ACI, respectively.Eight polyphenols including chlorogenic acid, 6,8-di-C-hexosyl apigenin, isoorientin, orientin, dicaffeoylquinic acid, biochanin A-O-glucoside, biochanin A-O-(malonyl)-glucoside, and licoisoflavone A were tentatively identified in ACI by HPLC/PDA/ESI-MS.ACI, within the range of 25-400 µg/ml, scavenged 1,1-diphenyl-2-picrylhydrazyl (DPPH) and O2. by 15-90% and 20-88%, respectively.The human natural killer (NK) cells were substantially activated by ACI, whereas T cells and granulocytes were slightly stimulated. Abbreviations used: ESI: electrospray ionization, HPLC: high performance liquid chromatography, PDA: photodiode array detector, MS: mass spectrometry, MS/MS: tandem mass spectrometry, MW: molecular weight, m/z: mass-to-charge ratio, FITC: fluorescent isothiocyanate, PE: phycoerythrin.

New Synthetic Pyrazine Carboxamide Derivatives as Potential Elicitors in Production of Secondary Metabolite in In vitro Cultures.

BACKGROUND: Silymarin, an active polyphenolic fraction of Silybum marianum, and high flavonoid content of Fagopyrum possess various interesting biological activities. The substituted pyrazine-2-carboxamides were previously used as effective elicitors of studied secondary metabolites. OBJECTIVE: To study the effect of new synthetic pyrazine carboxamide derivatives, N-(4-chlorobenzyl)-5-tert-butylpyrazine-2-carboxamide (1) and 3-(3-((trifluoromethyl) benzyl) amino) pyrazine-2-carboxamide (2), on flavonolignan and flavonoid production in S. marianum and Fagopyrumes culentum in vitro cultures. MATERIALS AND METHODS: Callus and suspension cultures were cultured on MS medium containing α-naphtaleneacetic acid or 2,4-D. Three elicitor concentrations for different exposure times were tested. Dried and powdered samples of callus and suspension cultures were extracted with methanol and analyzed by DAD-HPLC. RESULTS: Compound 1 showed as a good elicitor of taxifolin production. The effect on silymarin complex was less visible with a maximum between 24 and 48 h after 3.292 ×10(-4) mol/L concentration. The detailed analysis showed that silychristin was the most abundant. Compound 2 was effective in rutin production only in callus culture with maximum 24 h and 168 h after application of 3.3756 ×10(-3) mol/L concentration and 48 and 72 h after 3.3756 ×10(-4) mol/L concentration. CONCLUSION: From the results of the performed experiments, it can be concluded that compound 1 shows to be suitable elicitor for enhanced production of taxifolin and silychristin in S. marianum, mainly when 3.292 ×10(-4) mol/L concentration was used, and compound 2 is suitable for increase rutin production in callus cultures and less appropriate for suspension cultures of F. esculentum. SUMMARY: The influence of two new synthetic pyrazine-2-carboxamidesderivatives on secondary metabolite content of Silybum marianum and Fagopyrum esculentum in vitro cultures was tested.In S. marianum, the derivate N-(4-chlorobenzyl)-5-tert-butylpyrazine-2-carboxamide showed as a good elicitor of taxifolin production and less effective for silymarin complex production with silychristin as the most abundant.The derivate 3-(3-((trifluoromethyl) benzyl) amino) pyrazine-2-carboxamide is suitable for increase rutin production in callus cultures and less appropriate for suspension cultures of F. esculentum.

Short-term UV-B dose stimulates production of protective metabolites in Matricaria chamomilla leaves.

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.