Abstract

Aluminum (Al) toxicity induces damage at the metabolic level, affecting the yield and quality of barley plants. Silicon (Si) may exert a beneficial role on Al tolerance by mediating phenolics metabolism. The objective of this research was to evaluate the effect of Si on the improvement of phenolics metabolism in barley roots under Al stress. A hydroponic experiment was conducted by using two barley cultivars with contrasting Al tolerance. Plants were treated with Al (0 or 0.2 mM Al) and Si (0 or 2 mM) for 24 hours, 48 hours and 21 days. At harvest, growth parameters, Si and Al concentrations, soluble phenols and lipid peroxidation were assayed in the roots. In addition, lignin accumulation was visualized by Laser Scanning Confocal Microscopy. An increase in dry weight, root length, lignin accumulation and soluble phenol production was observed in both cultivars when Si was applied alone or in combination with Al. The enhancement of root phenol concentration and lignin accumulation was accompanied by a decrease of oxidative damage in Si supplied plants. More research is needed to elucidate the function of Si in the modulation of phenolics metabolism under Al toxicity.