title: Differential defense reactions in leaf tissues of barley in response to infection by Rhynchosporium secalis and to treatment with a fungal avirulence gene product.
abstract: Expression of defense-associated genes was analyzed in leaf tissues of near-isogenic resistant and susceptible barley cultivars upon infection by Rhynchosporium secalis. The genes encoding pathogenesis-related (PR) proteins PR-1, PR-5, and PR-9 are specifically expressed in the mesophyll of resistant plants, whereas a germin-like protein (OxOLP) is synthesized in the epidermis irrespective of the resistance genotype. Restriction-mediated differential display was employed to identify additional epidermis-specific genes. This resulted in the detection of another PR gene, PR-10, along with a lipoxygenase gene, LoxA, and a gene of unknown function, pI2-4, which are specifically induced in the epidermis of resistant plants. The gene encoding a putative protease inhibitor, SD10, is preferentially but not exclusively expressed in the epidermis. The fungal avirulence gene product NIP1 triggers the induction of the four PR genes only. At least two additional elicitors, therefore, must be postulated, one for the unspecific induction of OxOLP and one for the resistance-specific induction of LoxA, pI2-4, and SD10. PR-10 expression can be assumed to be the consequence of NIP1 perception by epidermis cells. In contrast, gene expression in the mesophyll is likely to be triggered by an as yet unknown signal that appears to originate in the epidermis and that is strongly amplified in the mesophyll.
authors.affiliation: Department of Biochemistry, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, D-50829 Köln, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Steiner-Lange
authors.forename: Achim
authors.initials: A
authors.lastname: Fischer
authors.forename: Annette
authors.initials: A
authors.lastname: Boettcher
authors.forename: Ila
authors.initials: I
authors.lastname: Rouhara
authors.forename: Hiltrud
authors.initials: H
authors.lastname: Liedgens
authors.forename: Elmon
authors.initials: E
authors.lastname: Schmelzer
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Knogge
mesh_terms: D001203:Ascomycota / Q000235:genetics / Q000472:pathogenicity*; D005656:Fungal Proteins / Q000235:genetics / Q000494:pharmacology; D015870:Gene Expression; D005800:Genes, Fungal; D017343:Genes, Plant; D001467:Hordeum / Q000235:genetics* / Q000382:microbiology* / Q000502:physiology; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000382:microbiology / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D014774:Virulence / Q000235:genetics
chemical_list: D005656:Fungal Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant