Antioxidant reactions in winter wheat seedlings of different cultivars exposed to the Pseudomonas syringae and its lipopolysaccharides in vitro

Pseudomonas syringae is the most common phytopathogenic bacterium with a wide range of target plants, which include important cereals such as wheat. One of the main pathogens of bacterial diseases of wheat is Pseudomonas syringae pv. atrofaciens. In some countries, wheat yield losses caused by this phytopathogenic bacterium reach 50%. Currently, the taxonomy of P. syringae includes more than 50 pathovars with varying degrees of adaptation to wheat lesions. One of them is Pseudomonas syringae pv. сoronafaciens. P. syringae pv. Coronafaciens is non-host pathogen for wheat. However, the infectionsof a wide range of crops, including wheat, with this pathogen attracts the attention of both researchers and specialiss of the agro-industrial complex. The study of the mechanisms of wheat resistance to host and non-host pathovars of P. syringae is of great interest, both in terms of in-depth study of the pathogen and in the perspective of selection of bacterial disease-resistant varieties of this strategically important grain crop for Ukraine. The aim of the study was to compare the antioxidant reactions of wheat seedlings of different winter wheat varieties under the grain exposition to P. syringae of different pathovars and their lipopolysaccharides (LPS). It was found that reactive oxygen species generation, as a mechanism of plant immune protection against phytopathogenic pseudomonads, is equally activated in the case of exposure to both host and nonhost pathovars and to a lesser extent in the case of the exposure with LPS of both pathovars. In grains of Favoritka variety (most sensitive to phytopathogenic pseudomonads) exposed to host pathovar, significant activation of antioxidant enzymes was observed. Exposure to the non-host pathovar causes sharp proline accumulation. Thus, the sensitivity of wheat seedlings to phytopathogenic host and non-host pathovars of phytopathogenic pseudomonads largely depends on the balanced functioning of the antioxidant defense system. Taken together, these data indicate the wheat cell oxidative metabolism as a target for selection of varieties resistant to phytopathogenic bacteria.

Redox Status, Biochemical Parameters and Mineral Elements Content in Blood of Turkey Hens Fed a Diet Supplemented with Yarrowia lipolytica Yeast and Two Bacillus Species

The probiotic-prebiotic properties and chemical composition of Yarrowia lipolytica yeast (YL), predisposes it for use as a turkey feed additive. The aim of the study was to determine whether YL in the diet of turkeys would exert more beneficial effect by stimulating antioxidant reactions and increasing mineral availability than Saccharomyces cerevisiae (SC). An additional aim of the study was to test whether the addition of a probiotic bacteria to feed containing Yarrowia lipolytica or Saccharomyces cerevisiae yeast would enhance their effect. The study was conducted on turkeys from seven to 112 days of age to determine the effects of a 3% addition of YL to the diet, as an alternative to the standard SC. It was analysed whether the use of a probiotic (Bacillus licheniformis, Bacillus subtilis) together with yeast would be more effective. Both the yeast (YL or SC) and the probiotic stimulated antioxidant mechanisms (increased CAT; reduced MDA), but the addition of SC was less effective. The inclusion of YL in the feed increased the plasma content of Ca, Mg, Cu, Zn and Fe in the blood turkeys and lowered the content of cholesterol and triacylglycerols. The combined use of yeast (YL or SC) with a probiotic enhances the antioxidant effect while inhibiting of lipid peroxidation. The combined use of yeast with a probiotic can be recommended in cases of stimulation of oxidative reactions (e.g., stress or infection)

Phytotoxicity, Bioaccumulation, and Degradation of Nonylphenol in Different Microalgal Species without Bacterial Influences

Nonylphenol (NP) is a contaminant that has negative impacts on aquatic organisms. To investigate its phytotoxicity, bioaccumulation, and degradation in algae without associated bacteria, six freshwater microalgae—Ankistrodesmus acicularis, Chlorella vulgaris, Chroococcus minutus, Scenedesmus obliquus, Scenedesmus quadricauda, and Selenastrum bibraianum—in bacteria-free cultures were studied. When exposed to 0.5–3.0 mg L−1 NP for 4 days, cell growth and photosynthesis, including maximal photochemistry (Fv/Fm), were suppressed progressively. The antioxidant responses of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) showed species differences. While the antioxidant enzymes in C. vulgaris and S. obliquus were more active with the increase of NP (0–3 mg L−1), they dropped in the other four algae at concentrations of 1 and 1.5 mg L−1. Therefore, C. vulgaris and S. obliquus were designated as NP-tolerant species and showed more conspicuous and faster changes of antioxidant reactions compared with the four NP-sensitive species. All six species degraded NP, but A. acicularis was more reactive at low NP concentrations (<1 mg L−1), suggesting its possible application in sewage treatment for its potential for effective NP removal from water bodies in a suitable scope. Therefore, the conclusion is that biodegradation of NP by algae is species specific.

Isoflavones and Isoflavone Glycosides: Structural-Electronic Properties and Antioxidant Relations—A Case of DFT Study

Isoflavonoids and isoflavonoid glycosides have drawn much attention because of their antioxidant radical-scavenging capacity. Based on computational methods, we now present the antioxidant potential results of genistein (1), biochanin A (2), ambocin (3), and tectorigenin 7-O-[β-D-apiofuranosyl-(1-6)-β-D-glucopyranoside] (4). The optimized structures of the neutral and radical forms have been determined by the DFT-B3LYP method with the 6-311G(d) basis set. From the findings and thermodynamic point of view, the ring B system of isoflavones is considered as an active center in facilitating antioxidant reactions. Antioxidant activities are mostly driven by O-H bond dissociation enthalpy (BDE) following hydrogen atom transfer (HAT) mechanism. Antioxidant ability can be arranged in the following order: compounds (4) > (3) > (2) > (1). Of comprehensive structural analysis, flavonoids with 4′-methylation and 6-methoxylation, especially 7-glycosylation would claim responsibility for antioxidant enhancement.