The potential for early generation selection to identify potato clones with resistance to Verticillium wilt

Abstract

Verticillium wilt (VW) of potato, caused primarily by the fungus Verticillium dahliae, results in yield loss and is therefore an important soil-borne disease. Resistance to VW exists in potato germplasm and is used by breeders during cultivar development. Breeders could make more rapid progress toward the development of VW resistant clones if they had an effective early generation selection strategy. The purpose of this study was to determine whether selection for VW resistance could be carried out in the first tuber generation on single hills. One hundred and fifty-two clones from 19 families were planted as single hills on a V. dahliae-infested field. Each plant was scored for vine maturity, VW symptom expression, yield, stem colonization (colony forming units (cfu), in dried basal stem segments) and incidence (percent infected stems). In the second clonal generation, which consisted of replicated four-hill plots, stem colonization scores and incidence values were used to identify clones which were more resistant than a moderately resistant cultivar and others which were more susceptible than a susceptible cultivar. The efficiency and reliability of the single-hill selection strategy, based on symptoms and yield, was then determined by comparison to the four-hill results. We determined that the best single-hill selection strategy was negative selection (discard clones with the lowest performance) with low stringency, based on yield.