title: Biochemical and molecular mechanisms involved in monogenic resistance responses to tomato powdery mildew.
abstract: The monogenic genes Ol-1, ol-2, and Ol-4 confer resistance to tomato powdery mildew Oidium neolycopersici via different mechanisms. The biochemical mechanisms involved in these monogenic resistances were studied by monitoring through time the association of H2O2 and callose accumulation with hypersensitive response (HR) and papilla formation. Our results showed that H2O2 and callose accumulation are coupled with both Ol-1- and Ol-4-mediated HR-associated resistance as well as with the ol-2-mediated papillae-associated resistance. Further, the transcriptomal changes related to these monogenic resistances were studied by using cDNA-amplification fragment length polymorphism. The expression profiling clarified that 81% of DE-TDF (differentially expressed transcript-derived fragments) were up-regulated upon inoculation with O. neolycopersici in both the compatible and Ol-1-mediated incompatible interactions, though with a difference in expression timing. Of these DE-TDF, more than 70% were not detected in the Ol-4-mediated resistance, while 58% were expressed in the ol-2-mediated resistance, generally at later timepoints. Sequence information suggested that most of these DE-TDF are related to genes involved in either basal defense or establishment of compatibility. In addition, DE-TDF (19%) specifically expressed in different incompatible interactions were identified. Expression patterns of some DE-TDF and marker gene GluB suggested that papillae-associated resistance exploits a different defense pathway from that of HR-associated resistance.
authors.affiliation: Laboratory of Plant Breeding, Wageningen University, PO Box 386, 6700 AJ Wageningen, The Netherlands.
authors.forename: Chengwei
authors.initials: C
authors.lastname: Li
authors.forename: Guusje
authors.initials: G
authors.lastname: Bonnema
authors.forename: Daidi
authors.initials: D
authors.lastname: Che
authors.forename: Lin
authors.initials: L
authors.lastname: Dong
authors.forename: Pim
authors.initials: P
authors.lastname: Lindhout
authors.forename: Richard
authors.initials: R
authors.lastname: Visser
authors.forename: Yuling
authors.initials: Y
authors.lastname: Bai
mesh_terms: D018076:DNA, Complementary / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D005936:Glucans / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D018551:Solanum lycopersicum / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D015854:Up-Regulation
chemical_list: D018076:DNA, Complementary; D005936:Glucans; C048306:callose; D006861:Hydrogen Peroxide