title: Differential expression of the TMV resistance gene N prevents a hypersensitive response in seeds and during germination.
abstract: The dominant tobacco mosaic virus (TMV) resistance gene N confers a hypersensitive response (HR) at the site of TMV infection and protects tobacco against systemic spread of the virus. To study N gene activity in seeds and early seedling development, the avirulence gene of N, the helicase domain (p50) of the TMV replicase, was constitutively expressed in a tobacco genotype without N (nn). Transgenic F1 expressing N and p50 were generated by crossing with an NN genotype. Surprisingly, Nn F1 seeds expressing p50 are viable and germinate. Only about 5 days after sowing, seedlings started to show an HR. This paralleled the upregulation of several pathogenesis-related and HR genes. The timing of the HR is consistent with the upregulation of N gene transcript 4-6 days after sowing. The expression of p50 has a stimulating effect on the N gene transcript level during germination. These results show that tobacco seeds and very young seedlings do not express a functional N gene product.
authors.affiliation: Institut für Genetik, Technische Universität Braunschweig, Spielmannstr. 7, 38106, Braunschweig, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Niemeyer
authors.forename: Jonas
authors.initials: J
authors.lastname: Ruhe
authors.forename: Fabian
authors.initials: F
authors.lastname: Machens
authors.forename: Reinhard
authors.initials: R
authors.lastname: Hehl
mesh_terms: D020090:Chromosome Segregation / Q000235:genetics; D003433:Crosses, Genetic; D004269:DNA, Bacterial / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics / Q000276:immunology; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics*; D018525:Germination / Q000235:genetics*; D009336:Necrosis; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology / Q000821:virology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000235:genetics / Q000276:immunology / Q000821:virology; D012639:Seeds / Q000235:genetics* / Q000254:growth & development / Q000276:immunology*; D014026:Nicotiana / Q000235:genetics / Q000276:immunology / Q000821:virology; D014027:Tobacco Mosaic Virus / Q000276:immunology*; D014170:Transformation, Genetic
chemical_list: D004269:DNA, Bacterial; C089425:N protein, Nicotiana glutinosa; D010940:Plant Proteins; D012333:RNA, Messenger; C036483:T-DNA