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Identification of Verticillium Wilt Resistance in U.S. Potato Breeding Programs

Jansky, Shelley H.
American journal of potato research 2009 v.86 no.6 pp. 504
Solanum tuberosum, potatoes, Verticillium dahliae, Verticillium wilt, disease resistance, genetic resistance, plant breeding, soil-borne diseases, disease control, breeding lines, genetic improvement, signs and symptoms (plants), field experimentation, stems, microbial colonization, infection, inoculum, Wisconsin
Verticillium wilt (VW), caused mainly by the soil-borne fungus V. dahliae, is a persistent and serious problem in potato production. Host-plant resistance offers an attractive control strategy, but most major cultivars are susceptible to VW. Resistance to VW was evaluated in 14 advanced clones from U.S. potato breeding programs and 11 cultivars. The two objectives of this study were to 1) determine the extent to which VW resistance exists in advanced selections in U.S. potato breeding programs and 2) test a selection strategy based on multiple measures of resistance. The three measures of resistance used in this study were symptom expression in the field, colonization of stem sap, and numbers of propagules in senescent stems. Resistant clones had low scores, but susceptible clones were highly variable for all three measures. An effective selection strategy utilizing all three measures of assessment can be used to separate true resistance from tolerance as follows: first, identify clones with low symptom expression, then measure sap colonization, and finish by establishing propagule levels in senescent stems. Based on this approach, breeders will be able to identify VW resistant, and not just VW tolerant, germplasm for future breeding efforts.