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The White Barley Mutant Albostrians Shows Enhanced Resistance to the Biotroph Blumeria graminis f. sp. hordei

¹Interdisciplinary Research Centre for Environmental Sciences, Institute of Phytopathology and Applied Zoology, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 26, D-35392 Giessen, Germany; ²Department of Biology, Humboldt-University Berlin, Chausseestr. 117, D-10115 Berlin, Germany

We performed cytological and molecular analyses of the interaction between the biotrophic barley powdery mildew fungus Blumeria graminis f. sp. hordei and white and green leaves of the barley albostrians mutant. The leaves have the same nuclear genotype but differ from each other in respect to plastid differentiation. White leaves showed enhanced penetration resistance to B. graminis f. sp. hordei, associated with higher epidermal H₂O₂ accumulation beneath the appressorial germ tubes and protein cross-linking in papillae. Very low basal salicylic acid content was found in white leaves, which further confirmed that H₂O₂ accumulation and penetration resistance in barley are independent of salicylic acid. Expression analysis of stress and defense-related genes, including such being involved in reactive oxygen species production and cell death regulation, revealed stronger constitutive or pathogen-induced transcript accumulation in white leaves. We discuss the data on the basis of the finding that white albostrians leaves exhibit a supersusceptible interaction phenotype with the hemibiotrophic fungus Bipolaris sorokiniana.

Additional keywords: GDP-dissociation inhibitor, MLO, OXLP.