title: Barley susceptibility factor RACB modulates transcript levels of signalling protein genes in compatible interaction with Blumeria graminis f.sp. hordei.
abstract: RHO (rat sarcoma homologue) GTPases (guanosine triphosphatases) are regulators of downstream transcriptional responses of eukaryotes to intracellular and extracellular stimuli. For plants, little is known about the function of Rho-like GTPases [called RACs (rat sarcoma-related C botulinum substrate) or ROPs (RHO of plants)] in transcriptional reprogramming of cells. However, in plant hormone response and innate immunity, RAC/ROP proteins influence gene expression patterns. The barley RAC/ROP RACB is required for full susceptibility of barley to the powdery mildew fungus Blumeria graminis f.sp. hordei (Bgh). We compared the transcriptomes of barley plants either silenced for RACB or over-expressing constitutively activated RACB with and without inoculation with Bgh. This revealed a large overlap of the barley transcriptome during the early response to Bgh and during the over-expression of constitutively activated RACB. Global pathway analyses and stringent analyses of differentially expressed genes suggested that RACB influences, amongst others, the expression of signalling receptor kinases. Transient induced gene silencing of RACB-regulated signalling genes (a leucine-rich repeat protein, a leucine-rich repeat receptor-like kinase and an S-domain SD1-receptor-like kinase) suggested that they might be involved in RACB-modulated susceptibility to powdery mildew. We discuss the function of RACB in regulating the transcriptional responses of susceptible barley to Bgh.
authors.affiliation: Phytopathology, School of Life Sciences Weihenstephan, Technical University of Munich, Freising, D-85354, Germany.
authors.forename: Vera
authors.initials: V
authors.lastname: Schnepf
authors.affiliation: Helmholtz Zentrum Muenchen, Department of Environmental Sciences, Institute of Biochemical Plant Pathology, Neuherberg, D-85764, Germany.
authors.forename: A Corina
authors.initials: AC
authors.lastname: Vlot
authors.affiliation: Helmholtz Zentrum Muenchen, Plant Genome and Systems Biology, Neuherberg, D-85764, Germany.
authors.forename: Karl
authors.initials: K
authors.lastname: Kugler
authors.affiliation: Phytopathology, School of Life Sciences Weihenstephan, Technical University of Munich, Freising, D-85354, Germany.
authors.forename: Ralph
authors.initials: R
authors.lastname: Hückelhoven
mesh_terms: D001203:Ascomycota / Q000472:pathogenicity*; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D001467:Hordeum / Q000235:genetics* / Q000382:microbiology*; D000090263:Leucine-Rich Repeat Proteins; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology*; D019441:Plant Epidermis / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000090263:Leucine-Rich Repeat Proteins; D010940:Plant Proteins; D011506:Proteins
keywords: DUF26; ROP; SERK; leucine-rich repeat; receptor-like kinase; wall-associated kinase