Plant & Animal Genomes XI Conference Plant & Animal Genomes XI ConferenceJanuary 11-15, 2003
Town & Country Convention Center
San Diego, CA
Workshop: Barley
The interaction of barley with the powdery mildew fungus Blumeria graminis is associated with the up- and down-regulation of a large number of host genes. Many of these differentially regulated genes are presumably involved in host defence. However, knowledge regarding defence-related gene function in cereals including barley is still very limited. Recessive mlo resistance alleles of the Mlo locus in barley control a non race-specific resistance response to infection by the obligate biotrophic fungus Blumeria graminis f.sp. hordei. This type of resistance, which is based on the formation of effective papillae preventing fungal penetration into epidermal cells, has been proven effective in the field for more than 20 years. Our approach is aimed at revealing gene function in the interaction transcriptome of mlo-resistant barley. The transcriptome of pathogen-attacked plants is being analysed by several approaches, in order to identify candidate genes for defense and disease resistance. One EST-based approach led to the definition of a set of approximately 3600 unigenes from pathogen-attacked, resistant barley leaf epidermis, which serves as a resource for gene-expression experiments on cDNA arrays as well as on Northern blots. Candidate genes identified by virtue of their regulation or their homology to known proteins are functionally tested in a transient assay system recently developed. This system allows the study of gain-of-gene-function by overexpression or loss-of-gene-function by gene silencing (RNAi) in single epidermal cells that are attacked by the powdery mildew fungus Blumeria graminis f.sp. hordei. Among other defense-related genes or gene-families, a sub-family of Germin-like proteins (HvGLP-4) with superoxide-dismutase activity was identified as component of basal resistance in barley against Blumeria graminis.