Selenium fortification stimulates antioxidant- and enzyme gene expression-related defense mechanisms in response to saline stress in Cucurbita pepo

Abstract

Salinity dramatically decreases the yield of most agricultural plants by causing osmotic and ionic stress that negatively impacts plant growth and development. As previously documented, selenium (Se), as a serviceable trace element, alleviates abiotic stress impacts, particularly salinity, on several plant species. This work was done perfectly to evaluate the impact of leaf feeding with Se on indicators of salt tolerance in Cucurbita pepo. Salt stress (9.45 dS m−1) noticeably raised electrolyte leakage (EL) and malondialdehyde (MDA) owing to the rise in the examined markers of oxidative stress like hydrogen peroxide (H2O2) and superoxide (O2•‒), and Na+ content. As a result, the contents of osmo-regulators and non-enzymatic antioxidants, activities of enzymatic antioxidants, and enzyme gene expressions were markedly increased. The salinity-induced oxidative stress noticeably diminished growth features, membrane stability index (MSI), relative water content (RWC), K+/Na+ ratio, pigment, nutrient, and Se contents. Fruit yield and fruit content of Se and vitamin C also diminished. However, the application of Se noticeably decreased LI and MDA owing to the minimization in the levels of O2•‒, H2O2, and Na+. This positive outcome was connected with a further rise in the levels and activities of osmo-regulators, the defensive system components, and enzymatic gene expressions, which were positively reflected in the growth features, RWC, MSI, K+/Na+ ratio, pigment, nutrient, and Se contents, as well as fruit yield and fruit quality. Our results indicate that 15 g Se applied per hectare attenuated the negative impacts of salt stress in C. pepo via various mechanisms such as minimization of reactive oxygen species (ROS; O2•‒ and H2O2) and Na+ contents, and improvement of leaf integrity, nutrient homeostasis, photosynthetic capacity, osmoregulators and antioxidant enzyme activities, enzymatic gene expressions, and the regulation of Na+ homeostasis.