Abstract

Aluminium (Al) toxicity in barley triggers negative effects on plant growth and development. Silicon (Si) can attenuate Al toxicity by both stimulating phenols metabolism and improving structural strengthening in plants. This study is aimed to evaluate the Si effect on accumulation and composition of lignin in barley plants under Al toxicity. A hydroponic experiment was conducted by using two barley cultivars (cv. Sebastian, Al-tolerant; cv. Scarlett, Al-sensitive) treated with two Al doses (0 or 0.2 mM Al) in combination with two Si doses (0 or 2 mM) for 21 days. At harvest, culm stretching rate and the concentration, composition and accumulation pattern of lignin in roots and shoots were assayed. For both cultivars, a greater culm stretching was observed in plants treated with 0.2 mM Al compared to those cultivated without Al-Si, whereas Si application decreased the stretching regardless of Al dose. The highest lignin accumulation in plant tissues was observed in both cultivars when Al and Si were applied simultaneously. Moreover, a greater lignin staining intensity was observed in cv. Scarlet Al-sensitive compared to cv. Sebastian Al-tolerant. On the other hand, Si increased the syringyl and total lignin concentration in shoots of cv. Sebastian exposed to Al stress. In cv. Scarlet supplied with both Al and Si, vanillyl concentration was improved in shoots, whereas cinnamyl and total lignin concentration was increased in roots. The degradation of lignin materials (vanillic acid: vanillin ratio) in shoots of cv. Sebastian and roots of cv. Scarlett were also enhanced by Si supply. Acknowledgments: FONDECYT Project 1161326 and Dirección de Investigación of Universidad de La Frontera.