Submitted to: Book Chapter
Publication Type: Book / chapter
Publication Acceptance Date: 3/27/2006
Publication Date: 6/30/2007
Citation: Simko, I., Jansky, S.H., Stephenson, S.A., Spooner, D.M. 2007. Genetics of resistance to pests and disease. In: Vreugdenhil, D., Bradshaw, J., Gebhardt, C., Govers, F., Taylor, M., MacKerron, D., Ross, H., editors. Potato Biology and Biotechnology: Advances and Perspectives. St. Louis, MO:Elsevier. p. 117-155. Interpretive Summary: In order to carry out breeding and genetics studies, genotypes must be correctly identified based on phenotypes. This may sound like a trivial matter. However, especially in disease and pest assays, the concept of resistance is necessarily linked to the screening method. Screening data must be used to assign resistance phenotypes, and rankings of clones may vary by screening method. There is often no black and white difference between resistant and susceptible phenotypes, so judgments must be made in order to assign phenotypes and, consequently, genotypes. Finally, most host-pathogen interactions are strongly influenced by the environment, so it is important to ultimately evaluate plants under the range of field conditions in which the crop will be grown.
Technical Abstract: Potato is a host to many pathogens that affect all parts of the plant and cause several reductions in the quantity and quality of the yield. The development of new cultivars that are more resistant to economically important pests and diseases is therefore one of the top priorities for the potato breeding programs worldwide. Numerous resistance genes were discovered in Solanum species and introgressed into the cultivated potato. The recent introduction of molecular marker techniques facilitated gene mapping and shifted orientation from the phenotype-based resistance genetics to the genotype-based based approaches. A number of loci conferring quantitative resistance (QRLs) and around forty single dominant genes (R-genes) conferring qualitative resistance were positioned on the potato molecular map. To date, eight of the mapped R-genes were isolated and molecularly characterized. The analysis of mapped and cloned resistance genes shows that they often occur in clusters and that some of them can respond to more than one elicitor. Ongoing research on resistance gene evolution will help us in understanding a dynamic interaction between potato and pathogens, and opens a way for development of more resistant cultivars.