title: Transgenic Pm3b wheat lines show resistance to powdery mildew in the field.
abstract: Plant resistance (R) genes are highly effective in protecting plants against diseases, but pathogens can overcome such genes relatively easily by adaptation. Consequently, in many cases R genes do not confer durable resistance in agricultural environments. One possible strategy to make the use of R genes more sustainable depends on the modification of R genes followed by transformation. To test a possible transgenic use of R genes, we overexpressed in wheat the Pm3b resistance gene against powdery mildew under control of the maize ubiquitin promoter. Four independent transgenic lines were tested in the greenhouse and the field during 3 years. The four lines showed a five- to 600-fold transgene overexpression compared with the expression of the endogenous Pm3b gene in the landrace 'Chul'. Powdery mildew resistance was significantly improved in all lines in the greenhouse and the field, both with naturally occurring infection or after artificial inoculation. Under controlled environmental conditions, the line with the strongest overexpression of the Pm3b gene showed a dramatic increase in resistance to powdery mildew isolates that are virulent on the endogenous Pm3b. Under a variety of field conditions, but never in the greenhouse, three of the four transgenic lines showed pleiotropic effects on spike and leaf morphology. The highest overexpressing line had the strongest side effects, suggesting a correlation between expression level and phenotypic changes. These results demonstrate that the successful transgenic use of R genes critically depends on achieving an optimal level of their expression, possibly in a tissue-specific way.
authors: Institute of Plant Biology, University of Zürich, Zürich, Switzerland.
authors: Susanne
authors: S
authors: Brunner
authors: Severine
authors: S
authors: Hurni
authors: Gerhard
authors: G
authors: Herren
authors: Olena
authors: O
authors: Kalinina
authors: Simone
authors: S
authors: von Burg
authors: Simon L
authors: SL
authors: Zeller
authors: Bernhard
authors: B
authors: Schmid
authors: Michael
authors: M
authors: Winzeler
authors: Beat
authors: B
authors: Keller
mesh_terms: D001203:Ascomycota / Q000187:drug effects / Q000472:pathogenicity; D003001:Cloning, Molecular; D060467:Disease Resistance; D035264:Flowers / Q000378:metabolism; D005659:Fungicides, Industrial / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D058685:Genetic Pleiotropy; D005822:Genetic Vectors / Q000235:genetics; D005838:Genotype; D008359:Mannose-6-Phosphate Isomerase / Q000235:genetics / Q000378:metabolism; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018547:Plant Stems / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D011401:Promoter Regions, Genetic; D019076:Transgenes; D014908:Triticum / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000382:microbiology*
chemical_list: D005659:Fungicides, Industrial; D010940:Plant Proteins; C486364:Pm3b protein, Triticum aestivum; D008359:Mannose-6-Phosphate Isomerase