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The effects of salinity stress on growth parameters and the activities of antioxidant enzymes (superoxide dismutase (SOD), peroxidase (POX), catalase (CAT), glutathione reductase (GR), and ascorbate peroxidase (APX)) were investigated in Arabidopsis thaliana during Phelipanche ramosa mediated biotic stress. The experiment was conducted using 100 mM NaCl on infected 18-dayold A. thaliana plants in Gamborg B5 medium. P. ramosa infection reduced root length and shoot dry weight (DW) in A. thaliana. After salt stress treatment shoot fresh weight (FW) decreased in A. thaliana plants infected with P. ramosa. Salt stress treatment produced a significant reduction in carotenoid and total chlorophyll content while it did not change the chl a/b ratio of infected plants. POX and APX activities increased during P. ramosa infection in A. thaliana. Additional NaCl treatment decreased the level of lipid peroxidation accompanied by an increment in SOD, POX, GR, CAT and APX activities, while chl a/b ratio and total chl content decreased. These results, presented for the first time, demonstrated induction of the antioxidant defense system against P. ramosa infection by NaCl treatment in A. thaliana. [ABSTRACT FROM AUTHOR]

Boron (B) is an essential micronutrient for normal growth of higher plants. On the other hand, its toxicity is also a significant problem that can limit plant growth on soils of arid and semi-arid environments in agricultural regions across the world. In this study, two tomato (Lycopersicon esculentum Mill.) varieties (SC2121 and SAFARI Fl) are used, and toxic effects of B treatment (3 mM) were studied. Germination was not affected, and seeds of both varieties germinated nearly to 100%. These in vitro germination experiments were accomplished in MS medium. Malondialdehyde (MDA) content, and antioxidant enzyme activites (superoxide dismutase (SOD), peroxidase (POX), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR)) were investigated in root and shoot tissues of tomato seedlings. Oxidative damage increased with 3-mM B treatment in tissues of SC2121 plants compared to control, and antioxidant enzyme activities were decreased, except APX. B toxicity inhibited only CAT activity in root tissues, but CAT, OR, SOD, POX and APX activities were inhibited in shoot tissues of SAFARI Fl. However, B toxicity in this variety did not cause oxidative damage. Root tissue of SAFARI F] variety, in particular, was found to be a better protection than SC2121. This might indicate that SAFARI F] variety is based on the protection of antioxidant enzymes. However, similar protections against B toxicity were not detected in shoot tissues of both varieties. [ABSTRACT FROM AUTHOR]

Glyphosate is a broad-spectrum herbicide that can widely be used in agricultural and non-agricultural fields. Glyphosate isopropylamine affects the inhibition of the bio-synthesis of aromatic amino acids, and also that of some enzymes involved in the shikimic acid pathway. The aim of this research was to study the effects of different con- centrations of glyphosate isopropylamine (0.5, 1, 2 and 5%) on the mitotic activity in A Ilium cepa L. root tip cells and the superoxide dismutase (SOD) and peroxidase (POX) activities in Allium cepa L. roots. Glyphosate isopropylamine concentrations of 0.5, 1 and 2% did not lead to a significant change in the mitotic activity compared to the control group. However, for the concentration of 5%, a steep decline was observed in 48-h treatment of the substance, in comparison to that of 24 h. Total SOD activity decreased in the 24-h treatment group of glyphosate isopropylamine compared to the control group, whereas with the concentrations of 2 and 5% no SOD activity was observed. However, the POX activity increased only with 1% concentration, with regard to the control group, whereas it did not change with the other concentrations. [ABSTRACT FROM AUTHOR]

Orobanche spp. (broomrapes) are holoparasitic angio-sperms that subsist on the roots of dicotyledonous plants. Broomrapes are the most destructive weeds since they ex- tract water and photosynthate directly from crop plants, causing crop yield and quality to reduce significantly. The occurrence of total superoxide dismutase and total per-oxidase activities during broomrape-sunflower interaction were studied on three different cultivars (cv. Pioneer 4223, cv. Sanay and cv. Isera) of Helianthus annuus. Total su- peroxide dismutase activities increased on day 7 post-in-oculation in cv. Pioneer 4223 and cv. Isera compared with control plants, whereas a decrease during all days in cv. Sanay was observed. In the variety of Orobanche-resistant cv. Pioneer 4223, the increases in the total superoxide dismutase activities were supported by the total peroxidase activities in the first 5 days, which indicate that the detoxification of the reactive oxygen species produced during the Orobanche penetration seems to be related to the Orobanche resistance in the sunflower. An increase has been determined in the total SOD activities from the first to the seventh day, but this increase was not found parallel to that in the total POX activities in cv. Isera.. This situation may indicate sensitivity for cv. Isera. Total per-oxidase activities increased for the first 7 days in cv. Sanay compared with control plants. Total superoxide dismutase and total peroxidase activities were not a statistically significant change during all days in treatment plants compared with control plants in cv. Sanay. This change in SOD activities may indicate sensitivity of both cv. Isera and cv. Sanay to broomrape unless they are treated with herbicide. [ABSTRACT FROM AUTHOR]

Elexa is a plant booster that elicits specific defense responses in various plants against certain fungal and bacterial diseases. Rather than killing hostile fungi that attack plants, Elexa acts as a preventative and stimulative agent to protect plants from pathogens. Elexa contains 4% chitosan. In the present study, a 0.1% concentration of Elexa was used to evaluate the biological efficiency in cucumber (Cucumis sativus L.), tomato (Lycopersicurn esculenturn Mill.) and potato (Solanum tube rosum L.) plants, as foliar spray against fungal (Botrytis cinerea Pers., gray mold), (Pseudoperanospora cubensis (Berk & Curt) Rostow, downy mildew), (Phytophtora infestans (Mont) de Bary, late blight) and bacterial (Pseudomonas lachryrnans (Smith & Ryan) Carsner, angular leaf spot) diseases in greenhouse conditions. Elexa was also used to evaluate the inhibitory effect of in vitro germination against B. cinerea Pers. and P. lachryrnans (Smith & Ryan) Carsner. Our results demonstrated that Elexa is a good plant booster for disease management and defense elicitation in commercial formulations. Elexa also exhibited inhibitory effects in in vitro germination of B. cinerea Pers. and P. lachrymans (Smith & Ryan) Carsner. It was observed that chitosan as well as elicitors, such as Elexa, produced with its chitosan content, provide 60% of protection against the damage caused by late blight, gray mold, downy mildew in potato and tomato plants, as well as angular leaf spot in cucumber, respectively. [ABSTRACT FROM AUTHOR]