Differential expression of putative cell death regulator genes in near-isogenic, resistant and susceptible barley lines during interaction with the powdery mildew fungus

• Published in: Plant molecular biology 2001-12, Vol.47 (6), p.739-748
• Main Authors: Hückelhoven, R, Dechert, C, Trujillo, M, Kogel, K H
• Format: Article
• Language: English
• Subjects: Airborne microorganisms; alkyl hydroperoxide reductase; Apoptosis; Apoptosis - genetics; Ascomycota - growth & development; ascorbate oxidase; ascorbate peroxidase; Barley; Blumeria graminis; Cells; DNA, Complementary - chemistry; DNA, Complementary - genetics; DNA, Complementary - isolation & purification; Gene expression; Gene Expression Regulation, Plant; Hordeum - genetics; Hordeum - microbiology; Hordeum vulgare; Immunization; Mla12 gene; Mlg gene; Molecular Sequence Data; Mortality; NADPH oxidase; oxidative burst; Plant Diseases - genetics; Plant Diseases - microbiology; Plant Leaves - genetics; Plant Leaves - microbiology; Proteins; Rac1 gene; Sequence Analysis, DNA; Signal transduction
• ISSN: 0167-4412; 1573-5028
• DOI: 10.1023/A:1013635427949

We analysed pathogenesis-related expression of genes, that are assumed to be involved in ubiquitous plant defence mechanisms like the oxidative burst, the hypersensitive cell death reaction (HR) and formation of localized cell wall appositions (papillae). We carried out comparative northern blot and RT-PCR studies with near-isogenic barley (Hordeum vulgareL. cv. Pallas) lines (NILs) resistant or susceptible to the powdery mildew fungus race A6 (Blumeria graminis f.sp. hordei, BghA6). The NILs carrying one of the R-genes Mla12, Mlg or the mlo mutant allele mlo5 arrest fungal development by cell wall appositions (mlo5) or a HR (Mla12) or both (Mlg). Expression of an aspartate protease gene, an ascorbate peroxidase gene and a newly identified cysteine protease gene was up-regulated after inoculation with BghA6, whereas the constitutive expression-level of a BAS gene, that encodes an alkyl hydroperoxide reductase, was reduced. Expression of a newly identified barley homologue of a mammalian cell death regulator, Bax inhibitor 1, was enhanced after powdery mildew inoculation. An oxalate oxidase-like protein was stronger expressed in NILS expressing penetration resistance. A so far unknown gene that putatively encodes the large subunit of a superoxide generating NADPH oxidases was constitutively expressed in barley leaves and its expression pattern did not change after inoculation. A newly identified barley Rac1 homologue was expressed constitutively, such as the functionally linked NADPH oxidase gene. Gene expression patterns are discussed with regard to defence mechanisms and signal transduction.