Effects of brassinosteroids on barley root growth,antioxidant system and cell division

Homobrassinolide (HBR), which is one of the most biologically active forms of Brassinosteroids (BRs), was used to examine the potential effects of hormone on root germination, antioxidant system enzymes and cell division of barley (Hordeum vulgare L.). Seeds were germinated between filter papers in 0.1, 0.5 and 1.0 μM HBR-supplemented distilled water for 48 h at dark with their controls. HBR application increased especially the primary root growth significantly with increasing concentrations when compared with the control materials and reached two fold increase in 1.0 μM HBR treated material. Treated and untreated control group roots were fixed in 1:3 aceto-alcohol and aceto-orcein preparations were made. Roots treated with HBR showed more mitotic activity, mitotic abnormalities and significant enlargements at the root tips when compared with control material. HBR application decreased total soluble protein content, superoxide dismutase (EC 1.15.1.1), catalase (EC 1.11.1.6) and peroxidase (EC 1.11.1.11) activities significantly at 1.0 μM HBR concentration. Data presented here is one of the first detailed analyses of HBR effect on barley root development.