Phytophthora infestans isolates lacking class I ipiO variants are virulent on Rpi-blb1 potato.
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.
Champouret
Nicolas
N
Wageningen UR Plant Breeding, Wageningen, The Netherlands.
Bouwmeester
Klaas
K
Rietman
Hendrik
H
van der Lee
Theo
T
Maliepaard
Chris
C
Heupink
Anika
A
van de Vondervoort
Peter J I
PJ
Jacobsen
Evert
E
Visser
Richard G F
RG
van der Vossen
Edwin A G
EA
Govers
Francine
F
Vleeshouwers
Vivianne G A A
VG
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
D005656:Fungal Proteins; C112546:IpiO1 protein, Phytophthora infestans