Effect of boric acid application on antioxidant enzymes activity and gene expression in Safflower (Carthamus tinctorius L) cultivars

Abstract: Boron is one of the most important micronutrients for plants. Plants may suffer from deficiency or with boron toxicity. Boron plays a role in significant physiological and biochemical events in plants such as synthesis of the cell wall, membrane integrity, antioxidation, transport of photosynthesis products to other organs of the plant. The enzyme activities of ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR) and superoxide dismutase (SOD) in three different safflower cultivars (Balcı, Dinçer and Remzibey) subjected to different boric acid concentrations (0, 5, 10, 15 mM) were measured spectrophotometrically, and the changes in the expression levels of the genes that encode these enzymes were obtained by quantitative RT-qPCR. When both the spectrophotometric measurements and the mRNA values were evaluated together, both the activity and mRNA values of APX and GR enzymes were found to be the highest in the Dinçer cultivar among the varieties treated with 15 mM boric acid, while the lowest values of these enzymes were determined in the Remzibey cultivar. According to the RT-qPCR results, the lowest SOD and CAT values were determined in Remzibey. The Dinçer cultivar was found to have the highest antioxidant capacity (APX, GR) to cope with oxidative stress caused by boric acid application at high concentrations. The sensitive Remzibey cultivar was found to have the lowest antioxidant capacity to cope with such oxidative stress. Balcı was found to be closer to Dinçer than to Remzibey in terms of boron tolerance. As a result, the boron-sensitive cultivar had low antioxidant activity.

Effect of Thymol on Soybean Seeds Germination: Physiological and Biochemical Analysis

Abstract Higher levels of reactive species of oxygen are harmful to plant tissues. This study evaluated the action of different doses of thymol on soybean seed germination, biometric analysis and enzymatic parameters; both involved in germination process. High doses of thymol affected the plantlet growth, but not hampered the germination.

Ascorbate peroxidase overexpression protects Leishmania braziliensis against trivalent antimony effects

Ascorbate peroxidase (APX) is a redox enzyme of the trypanothione pathway that converts hydrogen peroxide (H2O2) into water molecules. In the present study, the APX gene was overexpressed in Leishmania braziliensis to investigate its contribution to the trivalent antimony (SbIII)-resistance phenotype. Western blot results demonstrated that APX-overexpressing parasites had higher APX protein levels in comparison with the wild-type line (LbWTS). APX-overexpressing clones showed an 8-fold increase in the antimony-resistance index over the parental line. In addition, our results indicated that these clones were approximately 1.8-fold more tolerant to H2O2 than the LbWTS line, suggesting that the APX enzyme plays an important role in the defence against oxidative stress. Susceptibility tests revealed that APX-overexpressing L. braziliensis lines were more resistant to isoniazid, an antibacterial agent that interacts with APX. Interestingly, this compound enhanced the anti-leishmanial SbIII effect, indicating that this combination represents a good strategy for leishmaniasis chemotherapy. Our data demonstrate that APX enzyme is involved in the development of L. braziliensis antimony-resistance phenotype and may be an attractive therapeutic target in the design of new strategies for leishmaniasis treatment.

Assessment of Genetic Fidelity of in vitro Raised Plants in Swertia chirayita through ISSR, RAPD analysis and Peroxidase Profiling during Organogenesis

ABSTRACT An efficient in vitro regeneration protocol for medicinally important herb Swertia chirayita was developed and the genetic fidelity was assessed using RAPD and ISSR markers. The best shoot regeneration was observed on MS basal supplemented with 1.0 mg/L Benzyl amino purine (BAP) in combination with Indole-3-acetic acid (IAA) (0.5 mg/L) that resulted in the increase by multiplication rate (7.65) with an average of 33.33 numbers of shoots and average shoot length of 2.70 cm. It was further enhanced by the addition of adenine sulfate (0.007%) that resulted in an average of 42 shoots per clum with 4.13 cm of average shoot length and the increase in multiplication fold to 9.75 that further resulted in the reduced use of other cytokinins and auxins. The rooting was nearly 100 % on 1/4 MS augmented with 1.0 mg/L Indole butyric acid with maximum average root length of 5.1cm. Plantlets were successfully acclimatized with 85-90 % survival rate. Ascorbate peroxidase activity increased with the maximum activity during the shoot multiplication. Clonal fidelity has been checked by two marker systems ISSR and RAPD and regenerated plants showed high clonal fidelity.

The level of ascorbate peroxidase is enhanced in benznidazole-resistant populations of Trypanosoma cruzi and its expression is modulated by stress generated by hydrogen peroxide

Ascorbate peroxidases (APX) are class I heme-containing enzymes that convert hydrogen peroxide into water molecules. The gene encoding APX has been characterized in 11 strains of Trypanosoma cruzi that are sensitive or resistant to benznidazole (BZ). Bioinformatic analysis revealed the presence of two complete copies of the T. cruzi APX (TcAPX) gene in the genome of the parasite, while karyotype analysis showed that the gene was present in the 2.000-kb chromosome of all of the strains analyzed. The sequence of TcAPX exhibited greater levels of similarity to those of orthologous enzymes from Leishmania spp than to APXs from the higher plant Arabidopsis thaliana. Northern blot and real-time reverse transcriptase polymerase chain reaction (RT-PCR) analyses revealed no significant differences in TcAPX mRNA levels between the T. cruzi strains analyzed. On the other hand, Western blots showed that the expression levels of TcAPX protein were, respectively, two and three-fold higher in T. cruzi populations with in vitro induced (17 LER) and in vivo selected (BZR) resistance to BZ, in comparison with their corresponding susceptible counterparts. Moreover, the two BZ-resistant populations exhibited higher tolerances to exogenous hydrogen peroxide than their susceptible counterparts and showed TcAPX levels that increased in a dose-dependent manner following exposure to 100 and 200 µM hydrogen peroxide.