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Title: GENETIC VARIATION FOR RESISTANCE TO PHYTOPHTHORA INFESTANS IN A DIPLOID SOLANUM PHUREJA-S. STENOTOMUM HYBRID POTATO POPULATION IN PENNSYLVANIA

Author
item Haynes, Kathleen
item CHRIST, BARBARA - PENNSYLVANIA STATE UNIV.

Submitted to: Plant Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Late blight, caused by the fungus Phytophthora infestans, is an economically devastating disease of potatoes. Best known for its role in the Irish potato famine, new strains of this fungus are even more aggressive than the old strains. Some of these new strains are resistant to chemicals previously applied for control and have overcome single gene resistances in the potato. In this study we found resistance to late blight in a potato species closely related to commercial potatoes and found that this resistance to late blight was easily passed on to offspring from the resistant parent. This species has tremendous potential to furnish new genes for late blight resistance breeding. This genetic material will be valuable for pathologists and breeders involved in late blight research in understanding the relationship between the fungus and the potato, and in developing new cultivars for the potato industry with late blight resistance.

Technical Abstract: The emergence of new races of Phytophthora infestans has necessitated the search for additional sources of potato germplasm with resistance to late blight. Two-hundred eighty-one clones, representing 4 half-sibs from each of 72 families (there were seven missing clones), from a diploid hybrid population of Solanum phureja-S. stenotomum were evaluated with the check cultivar Atlantic' in a randomized complete block design consisting of two replications in field experiments in Pennsylvania in 1996 and 1997. Spreader rows were inoculated with the US-8, A2 mating type of P. infestans both years. Percent defoliation due to the late blight fungus was recorded in each plot three times towards the end of the growing season. There were significant differences among clones and the clone x environment interaction was also significant for AUDPC. Seventy-five percent of the diploid clones had a significantly lower mean AUDPC than Atlantic'. Broad-sense heritability of a mean basis was estimated as 0.79 with a 95% confidence interval of 0.74 to 0.84. Narrow-sense heritability on a family mean basis was estimated as 0.78 +/- 0.29. This population has the potential to contribute new germplasm to the late blight resistance breeding effort.