title: Phytophthora infestans isolates lacking class I ipiO variants are virulent on Rpi-blb1 potato.
abstract: A strategy to control the devastating late blight disease is providing potato cultivars with genes that are effective in resistance to a broad spectrum of Phytophthora infestans isolates. Thus far, most late blight resistance (R) genes that were introgressed in potato were quickly defeated. In contrast, the Rpi-blb1 gene originating from Solanum bulbocastanum has performed as an exclusive broad-spectrum R gene for many years. Recently, the RXLR effector family ipiO was identified to contain Avr-blb1. Monitoring the genetic diversity of the ipiO family in a large set of isolates of P. infestans and related species resulted in 16 ipiO variants in three distinct classes. Class I and class II but not class III ipiO variants induce cell death when coinfiltrated with Rpi-blb1 in Nicotiana benthamiana. Class I is highly diverse and is represented in all analyzed P. infestans isolates except two Mexican P. infestans isolates, and these were found virulent on Rpi-blb1 plants. In its C-terminal domain, IPI-O contains a W motif that is essential for triggering Rpi-blb1-mediated cell death and is under positive selection. This study shows that profiling the variation of Avr-blb1 within a P. infestans population is instrumental for predicting the effectiveness of Rpi-blb1-mediated resistance in potato.
authors.affiliation: Wageningen UR Plant Breeding, Wageningen, The Netherlands.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Champouret
authors.forename: Klaas
authors.initials: K
authors.lastname: Bouwmeester
authors.forename: Hendrik
authors.initials: H
authors.lastname: Rietman
authors.forename: Theo
authors.initials: T
authors.lastname: van der Lee
authors.forename: Chris
authors.initials: C
authors.lastname: Maliepaard
authors.forename: Anika
authors.initials: A
authors.lastname: Heupink
authors.forename: Peter J I
authors.initials: PJ
authors.lastname: van de Vondervoort
authors.forename: Evert
authors.initials: E
authors.lastname: Jacobsen
authors.forename: Richard G F
authors.initials: RG
authors.lastname: Visser
authors.forename: Edwin A G
authors.initials: EA
authors.lastname: van der Vossen
authors.forename: Francine
authors.initials: F
authors.lastname: Govers
authors.forename: Vivianne G A A
authors.initials: VG
authors.lastname: Vleeshouwers
mesh_terms: D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D014644:Genetic Variation; D008969:Molecular Sequence Data; D010802:Phylogeny; D055750:Phytophthora infestans / Q000235:genetics* / Q000378:metabolism* / Q000472:pathogenicity; D010935:Plant Diseases / Q000382:microbiology*; D011198:Solanum tuberosum / Q000382:microbiology*; D014774:Virulence
chemical_list: D005656:Fungal Proteins; C112546:IpiO1 protein, Phytophthora infestans