Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 22, 1997
Publication Date: N/A
Interpretive Summary: Late blight of potatoes, caused by the fungus Phytophthora infestans, is a significant threat to potato production in the United States, and all commercially important varieties are susceptible. Seventeen potato selections that reportedly had some resistance to late blight were collected from North American and European breeding programs. These selections were distributed to eight locations in the U.S. (FL, ME, MI, MN, ND, NY, PA and WI) and evaluated for their resistance to late blight in late blight infected field plots. Four selections from U.S. breeding programs were highly resistant to late blight at all locations: AWN86514-2, B0692-4, B0718-3 and B0767-2. However, all seventeen selections had more resistance to late blight than Russet Burbank, the most commercially important potato variety. This information will be valuable to potato breeders as these resistant selections are important parental materials in breeding for resistance to late blight.
Changes in the fungal pathogen Phytophthora infestans have posed a significant threat to potato production. Sources of resistance to these new genotypes of P. infestans need to be identified for potato breeders to have parental materials for crossing, and the phenotypic stability of late blight resistance in these potato clones needs to be determined. Seventeen potato clones which reportedly had some resistance to late blight were evaluated at eight locations in 1996. Percent infected foliage was recorded at approximately weekly intervals following the onset of the disease at each location. Area under the disease progress curve (AUDPC) was calculated. Clones were ranked for mean AUDPC within location and the nonparametric stability statistics, mean absolute rank differences and variance of the ranks, were analyzed for phenotypic stability. Neither of these statistics was significant, indicating a lack of genotype x environment interaction on the rankings of these clones across locations in 1996. The four clones with lowest AUDPC scores were U.S. clones AWN86514-2, B0692-4, B0718-3 and B0767-2. These clones should be useful parental materials for breeders seeking to incorporate genes for late blight resistance into potatoes.