Two barley cultivars, cv. Odessa (ruh1, universal susceptible) and cv. Hannchen (Ruh1), were used in this study. Barley seeds were dehulled and surface sterilized as described previously [16 (link)]. Both barley cultivars were grown at 23 °C and 16 h light in environmentally controlled growth chambers (Conviron, Winnipeg, MB, Canada) unless stated otherwise. For FoMV assays, barley was grown following conditions as described [21 (link)]. For this assay, an additional barley line SM89010 (Ruh1) was also used [20 (link)]. Nicotiana benthamiana plants were grown under similar conditions as the barley.
U. hordei strains were cultured at 22 °C in complete medium [22 (link)] with appropriate antibiotic when needed: 5 µg/mL of carboxin (Sigma-Aldrich, St. Louis, MO, USA) or 40 µg/mL of zeocin (Invitrogen, Carlsbad, CA, USA). All fungal strains used in this work are described inTable S1 . Pseudomonas syringae pv. atropurpurea (Psa) isolate 1304, a pathogen of Italian ryegrass [23 (link)], was cultured in Luria–Bertani (LB) medium at 28 °C with the appropriate antibiotics.
U. hordei strains were cultured at 22 °C in complete medium [22 (link)] with appropriate antibiotic when needed: 5 µg/mL of carboxin (Sigma-Aldrich, St. Louis, MO, USA) or 40 µg/mL of zeocin (Invitrogen, Carlsbad, CA, USA). All fungal strains used in this work are described in