Fig. 4: Indirect evidence for an involvement of the Stp complex in effector translocation.

a, A mutant lacking all seven stp complex genes can be partially rescued by wild-type strains. Plants were co-infected by SG200Δcomplex-Cmu1-mCherry and a mixture of compatible FB1 × FB2 wild-type strains. The Δcomplex mutant was visualized by its fluorescence at 2 d.p.i. Clamp connections are indicated by arrowheads, and non-fluorescent hyphae of wild type are labelled with asterisks. Images represent maximum projections of confocal z-stacks. Scale bars, 10 µm. b, Quantitative real-time PCR of indicated barley defence genes 2 d.p.i. with strains FB1:mock, FB1Δpep1 × FB2Δpep1 (UmΔpep1), FB1Δstp1 × FB2Δstp1 (UmΔstp1) and compatible Ustilago hordei wild-type strains (UhWT) and FB1 × FB2 (UmWT) as controls. The vertical axis displays expression values relative to water-infected leaf samples. Data shown are the mean values of relative expression and correspond to n = 5 biological replicates. Error bars indicate standard deviation. c, Values shown are the mean of penetrated viable barley epidermal cells quantified at 2 d.p.i. after staining with fluorescein diacetate (FDA). The number above each column indicates the total number of cells counted. All experiments were performed in five biological replicates. Error bars indicate standard deviation. Asterisk indicates significance P = 0.0251, calculated by an unpaired two-sided t-test.