Inheritance of resistance to early blight disease in a diploid potato population

Early blight disease, caused by Alternaia solani Sorauer, is a serious disease of potato foliage and tubers that occurs in most potato-growing regions world-wide. Developing new potato cultivars with resistance to early blight may reduce losses in the field and in storage, and lessen the need for fungicide applications. A total of 280 clones, derived from 72 maternal half-sib families from a diploid randommated hybrid population of Solanum phureja × Solanum stenotomum were examined for resistance to early blight. The clones that were evaluated in a replicated field trial for 2 years in Pennsylvania, USA, had similar early blight intensity both years. Significant differences were found among families, within families and for the interaction of years x within families. Broad-sense heritability for resistance, measured as area under the disease progress curve (AUDPC), was estimated as 0.73, with a 95% confidence interval of 0.65-0.78, and narrow-sense heritability was estimated as 0.61 ± 0.29 (P = 0.05). The correlation of AUDPC for early blight between years was 0.57 (P < 0.0001). These results suggest that this diploid population is worthy of use in breeding for early blight resistance.