Seed priming with 3-epibrassinolide alleviates cadmium stress in Cucumis sativus through modulation of antioxidative system and gene expression

Abstract

The current research work was designed to interpret the potential and mechanism of cadmium (Cd) stress alleviation in cucumber (Cucumis sativus L.) seeds primed with 3-epibrassinolide (3-EBL). Phenological traits of different cucumber cultivars revealed that cv. French green was most susceptible variety with respect to Cd stress. Seeds of cv. French green primed with 1, 5 and 10 μM of 3-EBL were grown in Cd spiked petri plates for 10 d. Oxidative injury caused by higher biosynthesis of reactive oxygen species (ROS) and malondialdehyde (MDA) damaged morphological features in addition to leaf relative water content (LRWC), photosynthetic constituents and gas exchange attributes in C. sativus seedlings under Cd toxicity. However, 3-EBL treatment assisted in subsidence of these detrimental effects of Cd-induced toxicity on growth attributes of exposed seedlings. Stress alleviation effect of 3-EBL was more prominent at 5 μM than at 1 and 10 μM. Lower Cd level in C. sativus leaves revealed the pragmatic engrossment of 3-EBL in Cd translocation. Seed priming with 3-EBL enhanced shoot growth and biomass production of C. sativus seedlings facing Cd stress. On the other hand, 3-EBL priming reduced MDA and ROS level in treated seedlings. Furthermore, expression level of genes including ethylene receptor CS-ERS, 1-aminocyclopropane-1-carboxylate oxidase1 (CSACO1), 1-aminocyclopropane-1-carboxylate oxidase2 (CsAOX), and 1-aminocyclopropane-1-carboxylate oxidase2 (CSACO2) increased in 3-EBL treated seedlings. From current study it was concluded that 3-EBL alleviated Cd-toxicity through enhanced activity of antioxidant enzymes besides regulation of stress-responsive genes in cucumber seedlings.