Fig. 5

Overexpression of Pf2826 transforms Ustilago maydis (FB1) into a biocontrol agent. Barley plants infected with Blumeria graminis f.sp. hordei (Bgh) were inoculated with U. maydis wild-type strain FB1 and two independent FB1 transformants overexpressing Pf2826 strains. A Stereomicroscopic and scanning electron microscopy (SEM) observation of biocontrol activity of wild type and overexpression strains at 36 hpi. Arrows show Bgh conidia; arrowheads show U. maydis structures. Black bars = 400 μm; white bars = 25 μm. B Biocontrol activity was rated on a scale of 0 to 5 where 0 = no activity and 5 = complete collapse of powdery mildew colonies at 24 and 36 hpi. Each value is the mean of three independent experiments ± standard error (SE). Each experiment comprised five leaves and three different sites per leaf (Additional file 7). *p < 0.01; indicates significant difference by Student’s t test