Effect of nitric oxide application on some stress factors in pepper (Capsicum Annum L.)

Under the influence of biotic and abiotic environmental factors, changes that occur in plants are defined as stress. These factors cause significant product loss in plants. Plants have a defense system that plays a role in reducing negative effects caused by stress factors. Reactive oxygen species (ROS) are produced in plants under stress conditions, and these compounds attack the plant cells, causing damage to the cells and cell deaths. Antioxidative stress enzymes play a role in reducing this harm called 'oxidative damage' and removing it from the plant. Nitric oxide (NO) is a very active molecule that has been proven to protect plants in various biological ways against damage caused by oxidative stress conditions. NO, which can easily pass through the cell membrane due to its lipophilic nature and acts as both intracellular and extracellular messenger, regulates many physiological and chemical processes. NO plays an important role in regulating cellular redox balances in plant cells and preventing oxidative damage sourced by reactive oxygen species. In this study, two different pepper varieties (çarliston Yalova 341, Doru 16) were selected as test plants and in these varieties, the effects of SNP applied at different levels (0, 25 and 50 µM), as an NO donor, on stress-induced by salinity (50 mM), heavy metals (zinc, copper, and cadmium), and boron (1 mM) were investigated. In the plants exposed to salt, heavy metal and boron stress, there was a significant decrease in the dry matter amount and photosynthetic pigment content, hydrogen peroxide (H2O2), proline, lipid peroxidation (MDA) and ascorbic acid (AsA) contents increased and in parallel, superoxide dismutase (SOD; EC 1.15.1.1). Ascorbate peroxidase (APX; EC 1.11.1.11), glutathione reductase (GR; EC 1.6.4.2), catalase (CAT; EC 1.11.1.6) and peroxidase (POD; EC 1.11.1.7) enzyme activities are also significantly increased. With NO application, stress parameters (H2O2, proline, MDA and AsA) and enzyme activities (SOD, APX, GR, CAT and POD) have significantly increased in plants