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item Costanzo, Stefano
item Christ, Barbara
item Haynes, Kathleen

Submitted to: Plant Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2004
Publication Date: 8/20/2004
Citation: Costanzo, S., B.J. Christ, and K.G. Haynes. 2004. Late blight resistance in a diploid full-sib potato family. Plant Breeding 123:377-381.

Interpretive Summary: Late blight is the most serious disease of potato worldwide. Resistance to late blight has been found in two diploid potato species that are closely related to cultivated potatoes. A cross was made between a late blight resistant and a susceptible parent and the offspring were evaluated for resistance to late blight in three Pennsylvania locations. The reaction to late blight in most of the offspring was consistent among the three locations. Some offspring were even more resistant than the resistant parent. These offspring will be studied to find molecular markers associated with late blight resistance. This information will be of value to potato breeders and pathologists involved in developing late blight resistant cultivars.

Technical Abstract: Late blight, caused by Phytophthora infestans (Mont.) de Bary, is the most destructive disease of potato worldwide. Since this pathogen can rapidly overcome major race-specific resistance genes, identifying the basis for enhanced quantitative resistance has become a crucial element for implementing advanced breeding strategies. A population of 230 full-sib progenies derived from a cross between two diploid hybrid Solanum phureja ´ S. stenotomum clones were evaluated for foliage resistance against late blight in replicated trials at multiple locations of Pennsylvania between 1999 and 2002. In field experiments, plants were evaluated visually for percent defoliation, and area under the disease progress curve (AUDPC) was determined. The two parents and three control cv. (`Atlantic¿, `Kennebec¿ and `Katahdin¿) were included in all trials. In all three experiments the presence of a significant number of clones exhibiting transgressive segregation were observed. There were significant differences among environments as well as among clones, and the clone environment ' interaction was also significant. However, the rep(env) effect was not significant. Stability analysis revealed that 37 clones with a significant contribution to the overall environment ´ clone interaction. Broad-sense heritability for resistance, measured as AUDPC, was estimated as 0.67, with a 95% confidence interval of 0.65-0.78. The overall results indicate the presence in this potato family of a high level of field resistance against late blight. This segregating diploid family appears to be a good candidate for QTL mapping to identify and characterize the genetic components of partial late blight resistance.