title: Decreased defense gene expression in tolerance versus resistance to Verticillium dahliae in potato.
abstract: Verticillium dahliae Kleb., a soil-borne fungus that colonizes vascular tissues, induces wilting, chlorosis and early senescence in potato. Difference in senescence timing found in two diploid potato clones, 07506-01 and 12120-03, was studied and genetic variation in response to V. dahliae infection was identified as a causal factor. The clone, 07506-01, was infected with V. dahliae but did not develop symptoms, indicating tolerance to the pathogen. The other diploid clone, 12120-03 had low levels of pathogen with infection and moderate symptoms indicating partial resistance. 07506-01 was found to carry two susceptible alleles of the Ve2 gene and 12120-03 carried one Ve2 resistant and one susceptible allele. Infected leaves of the two clones were compared using gene expression profiling with the Potato Oligonucleotide Chip Initiative (POCI) microrarray. The results provide further evidence for differences in response of the two clones to infection with V. dahliae. Chlorophyll biosynthesis was higher in the tolerant 07506-01 compared to partially resistant 12120-03. On the other hand, expression of fungal defense genes, Ve resistance genes and defense phytohormone biosynthetic enzyme genes was decreased in 07506-01 compared to 12120-03 suggesting defense responses were suppressed in tolerance compared to resistance. Transcription factor gene expression differences pointed to the WRKY family as potential regulators of V. dahliae responses in potato.
authors.affiliation: Potato Research Centre, Agriculture and Agri-Food Canada, PO Box 20280, Fredericton, NB E3B 4Z7, Canada. Helen.Tai@agr.gc.ca
authors.forename: Helen H
authors.initials: HH
authors.lastname: Tai
authors.forename: Claudia
authors.initials: C
authors.lastname: Goyer
authors.forename: H W
authors.initials: HW
authors.lastname: Bud Platt
authors.forename: David
authors.initials: D
authors.lastname: De Koeyer
authors.forename: Agnes
authors.initials: A
authors.lastname: Murphy
authors.forename: Pedro
authors.initials: P
authors.lastname: Uribe
authors.forename: Dennis
authors.initials: D
authors.lastname: Halterman
mesh_terms: D060467:Disease Resistance / Q000235:genetics*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D007113:Immunity, Innate / Q000235:genetics; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D018515:Plant Leaves / Q000235:genetics / Q000382:microbiology; D012988:Soil Microbiology; D011198:Solanum tuberosum / Q000235:genetics* / Q000254:growth & development / Q000382:microbiology; D020172:Verticillium / Q000235:genetics* / Q000472:pathogenicity