Title: Heritability of Resistance to Common Scab in Diploid Potatoes Authors
|Christ, Barbara - PENN STATE UNIVERSITY|
|Burkhart, Christopher - PENN STATE UNIVERSITY|
Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 25, 2008
Publication Date: June 1, 2009
Citation: Haynes, K.G., Christ, B., Burkhart, C., Vinyard, B.T. 2009. Heritability of Resistance to Common Scab in Diploid Potatoes. American Journal of Potato Research. 86:165-170. Interpretive Summary: Common scab is a serious soil-borne potato disease that causes superficial, raised, or deeply pitted lesions on tubers. These lesions, particularly the pitted ones, render the tuber unmarketable, but even the superficial or raised lesions detract from their marketability. There is very little resistance to common scab in commercial potato varieties. We examined a potato species that is closely related to commercial potatoes to determine if it had resistance to common scab that could be used in breeding to develop scab resistant varieties. We determined that this other potato species did not have enough resistance to common scab to make it worthwhile to use in breeding for resistance. This information will be useful to breeders, geneticists, and pathologists in encouraging them to examine other potato species in the search for sources of resistance to common scab disease.
Technical Abstract: Common scab, caused by several species of Streptomyces, is a serious soil-borne disease of potatoes that may cause superficial, raised or pitted lesions on potato tubers. Little is known about the genetic basis of resistance to this disease. The purpose of this study was to determine if genetic resistance to common scab exists in a diploid Solanum phureja-S. stenotomum (phu-stn) population and to estimate broad-sense (H) and narrow-sense (h2) heritability for resistance to common scab. Two hundred seventy-one clones from a randomly mated phu-stn population were grown from 2003-2005 in naturally Streptomyces infested soil in a grower’s field in Northampton Co., PA, in a randomized complete block design replicated twice. After harvest, the proportion of tubers with scab lesions was determined. The variable analyzed by the general linear models procedures in SAS using the maximum likelihood estimation method was the arcsine ( v proportion of scabby tubers). There were significant differences among clones and the year x clone interaction was significant. H for resistance was estimated as 0.18 with a 95% confidence interval of 0.15 to 0.35. The clonal source of variation was partitioned into among families and within families. All the variation occurred within families. There was no additive genetic variance for resistance in this population, hence, h2 was estimated as 0.00. Levels of resistance to common scab cannot be improved by breeding in this diploid population. This information will be useful to potato breeders, geneticists, and pathologists.