Submitted to: Plant Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/22/2000
Publication Date: N/A
Citation: Interpretive Summary: The two most important foliar diseases of potatoes worldwide are late blight and early blight. In a previous study, we determined that the heritability of resistance to late blight was high in a diploid potato breeding population. In this study we determined that the heritability of resistance to early blight was moderately high in this same diploid potato population. We also found that the relationship between early blight resistance and late blight resistance was low. This suggests that there are both general and specific fungal resistance genes in this population. With such high heritability estimates for resistance, progress in improving levels of resistance to either early blight or late blight in potatoes can be realized rapidly. However, improving levels of resistance to both early blight and late blight will be much more difficult. This research makes a significant contribution to understanding the genetic control of potato early blight resistance. Potato breeders and growers will benefit from this information.
Technical Abstract: Early blight disease is a serious disease of potatoes worldwide. Foliage and tubers may become infected. Developing new potato cultivars with resistance to early blight may reduce losses and lessen the need for fungicide applications. We examined 280 clones from diploid population of Solanum phureja x S. stenotomum for resistance to early blight. Results were used to correlate the response to early blight with the response to late blight. The clones were evaluated in a replicated field trial for 2 years in Pennsylvania. Percent defoliation caused by the early blight fungus was estimated visually three times near the end of the growing season. Area under the disease progress curve (AUDPC) was calculated and revealed that early blight intensity was similar for both years. Significant differences were found among families, within families, and for the interaction of years x within families. Broad-sense heritability was estimated as 0.73 (0.65 to 0.78). Narrow-sense heritability was estimated as 0.61 +/- 0.29. The simple correlation of AUDPC for early blight and late blight by years ranged from 0.25 to 0.35. The correlation of AUDPC for early blight between years was 0.57. It appears that the population has genes for general fungal resistance and resistance to specific fungal pathogens.