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The RPi-mcd1 Locus from Solanum microdontum Involved in Resistance to Phytophthora infestans, Causing a Delay in Infection, Maps on Potato Chromosome 4 in a Cluster of NBS-LRR Genes

July 2008 , Volume 21 , Number  7
Pages  909 - 918

M. Y. Adillah Tan, Ronald C. B. Hutten, Carolina Celis, Tae-Ho Park, Rients E. Niks, Richard G. F. Visser, and Herman J. van Eck

Laboratory of Plant Breeding, Wageningen University and Research Centre, P.O. Box 386, 6700 AJ, Wageningen, The Netherlands

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Accepted 3 March 2008.

The distinction between field resistance and resistance based on resistance (R) genes has been proven valid for many plant--pathogen interactions. This distinction does not seem to be valid for the interaction between potato and late blight. In this study, a locus involved in late blight resistance, derived from Solanum microdontum, provides additional evidence for this lack of distinction. The resistance is associated with a hypersensitive response and results in a delay of infection of approximately 1 to 2 weeks. Both a quantitative as well as a qualitative genetic approach were used, based on data from a field assay. Quantitative trait locus (QTL) analysis identified a QTL on chromosome 4 after correction of the resistance data for plant maturity. A qualitative genetic analysis resulted in the positioning of this locus on the short arm of chromosome 4 in between amplified fragment length polymorphism marker pCTmACG_310 and cleaved amplified polymorphic sequence markers TG339 and T0703. This position coincides with a conserved Phytophthora R gene cluster which includes R2, R2-like, RPi-blb3, and RPi-abpt. This implies that RPi-mcd1 is the fifth R gene of this nucleotide-binding site leucine-rich repeat cluster. The implications of our results on R-gene-based and field resistance are discussed.

© 2008 The American Phytopathological Society