Abstract
Wheat blast, caused by the Magnaporthe oryzae Triticum (MoT) pathotype, threatens wheat production in many countries, including Bangladesh. Traditional fungicides are ineffective in combating this pathogen, and no resistant wheat variety is available. This study investigated the mechanism of wheat blast suppression by a nanostructured TiO2 nanocatalyst (NC) that generates reactive oxygen species through a photocatalytic process under daylight settings. In the presence of sunlight, the NCs displayed a high antifungal activity against MoT in vitro (minimum inhibitory concentration - MIC 0.025mg/ml), as well as suppressed conidial formation and mycelial growth of MoT. Moreover, the fungal biomass was drastically reduced at NC concentrations >= 0.5mg/ml. In vivo seedling assays showed inhibition of wheat blast when wheat seedlings were artificially inoculated with conidia. Under daylight conditions, NCs at a concentration from 0.1 to 0.5mg/ml can protect wheat plants from MoT likely by inducing oxidative stress in the pathogen. Field trials of TiO2 NCs prevented more than 90% of disease incidence, with optimum yields, at NC concentrations >= 0.5 mg/ml. These results indicate that daylight-driven rechargeable NCs effectively suppress MoT in vitro and control wheat blast in the field.