Submitted to: American Journal of Potato Research
Publication Type: Abstract Only
Publication Acceptance Date: February 28, 2005
Publication Date: January 20, 2006
Citation: Haynes, K.G., Christ, B.J. 2006. Improvements in foliar late blight resistance in a diploid hybrid Solanum phureja-S. stenotomum population. [abstract]. Amer. J. Potato Res. 83:112-113.
Foliar late blight, caused by Phytophthora infestans, is a devastating disease of potatoes worldwide. In 1996 we initiated a breeding project to improve the levels of late blight resistance in a diploid hybrid population of Solanum phureja-S. stenotomum. The purpose of this study was to determine if resistance to late blight in this population could be improved by recurrent maternal half-sib selection. Four clones from each of 72 maternal half-sib families were evaluated for resistance in replicated field trials in Pennsylvania in 1996 and 1997 (cycle 1), and their offspring were evaluated in 2003 and 2004 (cycle 2). 'Atlantic' was included as a check variety at all sites. Percent infected foliage was recorded three times towards the end of the growing season each year and used to compute area under the disease progress curve (AUDPC). Mean AUDPC for 'Atlantic' in cycles 1 and 2 was 863 and 854, respectively. Mean AUDPC of all diploid clones in cycles 1 and 2 was 652 and 556, respectively. Late blight resistance in the cycle 1 population was skewed towards susceptibility; in the cycle 2 population it was normally distributed. Narrow-sense heritability for resistance in the cycle 1 and cycle 2 populations was estimated as 0.78 and 0.77, respectively; additive genetic variance was estimated as 10,960 and 12,636, respectively; phenotypic variance was estimated as 14,088 and 16,375, respectively. Predicted and realized genetic gain from cycle 1 to cycle 2 was -80 and -96, respectively. Recurrent maternal half-sib selection is an effective way to improve resistance to late blight in this population and maintain adequate genetic diversity for further enhancement efforts.