The Biochemical Response of Soybean Cultivars Infected by Diaporthe Species Complex.

Oxidative stress in soybean plants infected with Diaporthe isolates was evaluated in order to select (1) the least aggressive inoculation method, (2) to determine the most aggressive Diaporthe isolate, and (3) to determine the most tolerant soybean cultivar to this isolate. Based on the present malondialdehyde (MDA) content, the main end product of the lipid peroxidation process, and the biomarker for oxidative stress, the mycelium contact method was chosen as the least aggressive inoculation method, compared to the toothpick method and plug method. The activity of the antioxidant enzymes (superoxide-dismutase (SOD), catalase (CAT), and peroxidase (PX)), the reduced glutathione (GSH) content, and the level of lipid peroxidation (LP) were measured in soybean cv. Sava infected by five different Diaporthe species (DPM1F-D. aspalathi, DPC/KR19-D. caulivora, DPC004NY15-D. eres, 18-DIA-SOY-14-D. gulyae, and PL157A-D. longicolla). The most pathogenic Diaporthe species to cv. Sava was D. eres. The screening of the antioxidant enzymes activity in the leaves of 12 different soybean cultivars (Altona, Atlas, Capital, Chico, CX134, Favorit, Lakota, McCall, Morsoy, Strain, Rubin, and Victoria) infected with D. eres by the mycelium contact inoculation method showed that Capital, McCall, and Morsoy were the cultivars with the highest tolerance to D. eres, followed by Chico, Favorit, Lakota, and Rubin. The most sensitive cultivars were Atlas, CX134, Victoria, and Strain.

Susceptibility of the Most Popular Soybean Cultivars in South-East Europe to Macrophomina phaseolina (Tassi) Goid.

Oxidative stress in soybean seedlings and the length of the soybean stem lesions infected with the fungus Macrophomina phaseolina (Tassi) Goid were evaluated to determine the most tolerant soybean cultivar to this pathogen. The level of superoxide anion radical (O2•-) production, the activity of the antioxidant enzyme superoxide-dismutase (SOD), and the intensity of lipid peroxidation (LP) were measured in four soybean cultivars: Favorit, Atlas, Victoria, and Rubin. Results showed that O2•- radical production and SOD activity were the most elevated in the cv. Favorit inoculated with M. phaseolina, while the level of lipid peroxidation intensity was the lowest compared to the control. This indicates that the soybean cv. Favorit has managed to prevent infection with M. phaseolina. Furthermore, higher O2•- radical production and lower SOD enzyme activity were measured in cv. Victoria, with enhanced lipid peroxidation. This means that the cv. Victoria was infected with M. phaseolina, and was the most sensitive. None of the tested oxidative stress parameters showed a significant difference in the cvs. Atlas and Rubin compared to the control. Furthermore, the highest lesion length was measured in the cv. Victoria, followed by cv. Favorit, while the lowest lesion length was measured in the cv. Atlas followed by the cv. Rubin; and thus, the cv. Atlas followed by the cv. Rubin, were the most tolerant soybean cultivars to this pathogen.

Chemical Composition of Ambrosia trifida L. and Its Allelopathic Influence on Crops.

Phytotoxic substances released by invasive plants have been reported to have anti-pathogen, anti-herbivore, and allelopathic activity. The aim of this study was to determine the allelopathic influence of the Ambrosia trifida L. on oxidative stress parameters (the lipid peroxidation process; reduced glutathione (GSH) content; and activity of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), and peroxidase (PX)) and phenolic compounds (total phenolic and tannin content) in maize (Zea mays L.), soybean (Glycine max L.), and sunflower (Helianthus annuus L.) crops to explore the effect of released allelochemicals through A. trifida root on crops. An analysis by HPLC confirmed the presence of protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, and syringic acid as major components in the A. trifida. Based on the obtained results for oxidative stress parameters, it can be concluded that the sunflower was the most sensitive species to A. trifida allelochemicals among the tested crops. The other two crops tested showed a different sensitivity to A. trifida. The soybean did not show sensitivity, while the maize showed sensitivity only 10 days after the sowing.

Phytochemical characterization and effects on cell proliferation of Pinus nigra Arn. bark.

Pinus nigra Arn. bark extracts from Mokra gora (MG) and Tara mountains were analyzed with regard to their polyphenolic profile and antioxidative and antiproliferative activity. The ethanol extract from MG showed the highest phenolic, flavonoid, tannin, and proanthocyanidin content when compared with the acetone and methanol extracts from both sites. The same extract exhibited the highest ABTS (2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt) and ferric reducing antioxidant power (FRAP) radical scavenging ability and total antioxidant activity (TAA). On the basis of high-performance liquid chromatography analysis, catechin, caffeic, syringic, p-coumaric, and ferulic acids were predominantly present in the MG extracts. The ethanol extract from MG was rich in syringic acid, epicatechin and its derivatives, and ferulic acid and its derivatives. The bark extracts also exerted a high cytotoxic bioactivity against all evaluated cell lines (HeLa, MCF7, HT-29, and MRC-5). The antiproliferative activity of P. nigra bark is probably related to the ferulic acid content and its synergistic activity to caffeic acid and taxifolin. The antioxidative role of the presented phenols was confirmed through the obtained significant linear correlation between the total phenolic content and DPPH (r = .934) as well as the FRAP% of the extracts (r = .948). Also, the TAA significantly depended on the proanthocyanidins (r = .902) and tannin contents (r = .914). The composition of the presented compounds could be related to promising antioxidant and antiproliferative efficacy of MG bark.

Determination of phytoestrogen composition in soybean cultivars in Serbia.

The growing clinical interest and use of soybean-based food products and extracts to increase dietary phytoestrogen intake have led to medical interest in the precise determination of the phytoestrogen composition of soybean products. We have analyzed the composition of these compounds in 20 domestic and introduced varieties of genetically non-modified soybean genotypes grown under the same agroecological conditions. The isoflavone content of soybeans cultivated in this region of Serbia has not been previously reported. The assays were performed, after extraction with methanol-water (8:2, v/v), by C18 reversed phase high-performance liquid chromatography coupled with photodiode array detection. The total phytoestrogen concentration was found to be between 2.24 and 3.79 mg g(-1) dry bean weight. The total concentration of daidzein and its derivatives ranged from 0.96 to 1.82 mg g(-1), total glyciteines from 0.34-0.53 mg g(-1), and all genistein derivatives from 0.86-1.67 mg g(-1) dry bean weight. Given the high biological potency of phytoestrogens and their metabolic conversion products, our data suggest that phytoestrogen content screening could be a useful tool in the selection of soybean genotypes with improved health promoting characteristics.

Polyphenol contents and antioxidant activity of Maydis stigma extracts.

The antioxidant activity and contents of various polyphenol classes in the silks of fifteen maize hybrids with economic importance in Serbia were evaluated. Total polyphenols, tannins and proanthocyanidins were determined spectrophotometrically, after extraction of plant material with 70% aqueous acetone under sonication at room temperature. In addition, flavonoid content was determined. Antioxidant activity of aqueous acetone extracts was evaluated by FRAP assay. A positive linear correlation between antioxidant activity and contents of all investigated polyphenol classes was established. The highest antioxidant activity was observed in the extract of NS 640 hybrid, which had high levels of all polyphenol classes examined. Results suggested strongly that polyphenol content should be considered as an important feature of the herbal drug Maydis stigma. For that reason, the biological source of this herbal drug needs to be more precisely defined, as observed activities and polyphenol contents were greatly dependent on plant material source.