Wheat resistance to leaf blast mediated by silicon

Blast, caused by Pyricularia grisea, is one of the most important diseases of wheat. The effects of silicon (Si) on this wheat disease were studied. Plants of wheat cultivars Alian double dagger a and BH-1146 were grown in plastic pots containing Si-deficient soil amended with either calcium silicate (+Si) or calcium carbonate (-Si). The content of Si in leaf tissue was significantly increased by 14.8% for the +Si treatment. There were no significant differences between Si treatments for calcium content, so variations in Si only accounted for the observed differences in the level of blast resistance. The incubation period was significantly increased, on average, by 28.2% for the +Si treatment. The area under blast progress curve and the number of lesions per cm(2) of leaf area significantly decreased by 31 and 45%, respectively, for the +Si treatment. There was no significant effect of Si on final disease severity. The concentration of total soluble phenolics observed in both cultivars supplied with Si did not apparently play any role in the increased blast resistance. The highest content of lignin-thioglycolic acid derivatives was found in plants from both cultivars with Si during the time period evaluated. Chitinase activity was high at the intermediate stages of fungal infection in both cultivars supplied with Si. Peroxidase activity was found to be high at the late stage of fungal infection for both cultivars supplied with Si and seemed to play a role in enhancing wheat blast resistance. Polyphenoloxidase activity also apparently had no effect on resistance for any of the treatments. These overall results revealed the potential of Si to decrease wheat susceptibility to blast.