Infection process of Bipolaris sorokiniana on wheat leaves is affected by silicon

The supply of silicon (Si) to wheat plants may potentiate their resistance against infection by Bipolaris sorokiniana. Considering that there is no information regarding how Si affects the infectious process of this fungus on wheat leaves, this study intended to investigate, using light and scanning electron microscopy, the effects of Si supply on the infection process of B. sorokiniana on wheat leaves at tissue level. For that, leaf segments of -Si and +Si plants were prepared. The number of necrotic brown cells and the degree of browning of necrotic cells were determined for each infection site. As results, it was found that the number of brown epidermal cells and the frequency of infection sites showing browning were significantly lower on leaves of +Si plants. On the leaves of -Si plants, an intense dissolution of the wax layer also occurred and hyphae were found inside the disorganized epidermal cells. On leaves of +Si plants, degradation of the wax layer was observed only in areas close to conidia. Within 96 hours after inoculation, a dense network of hyphae had colonized the leaf surface of -Si plants, in striking contrast to +Si plants, for which only sparse hyphae were found.