|QU, XINSHUN - Pennsylvania State University|
Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/27/2018
Publication Date: 8/30/2018
Citation: Haynes, K.G., Qu, X. 2018. Three cycles of recurrent maternal half-sib selection continue to reduce foliar late blight in a diploid hybrid Solanum phureja-S. stenotomum population. American Journal of Potato Research. https://doi.org/10.1007/s12230-018-9681-x.
Interpretive Summary: Late blight is the most serious disease of potatoes worldwide. The pathogen responsible for this disease has been able to overcome most single gene sources of resistance. We have developed a population of potatoes with multiple gene resistance. This population has been subjected to three generations of selection for resistance. In this study, we document additional improvements in the levels of resistance to late blight in this population. This population is highly resistant to late blight and additional selection for resistance is predicted to continue to improve the levels of resistance in this population. This information will be of interest to potato breeders trying to develop late blight resistant potato varieties.
Technical Abstract: Increasing levels of foliar resistance to late blight, caused by Phytophthora infestans, have previously been reported through two cycles of recurrent maternal half-sib selection in a diploid hybrid population of Solanum phureja-S. stenotomum. The objective of this study was to determine if continued improvements for resistance to late blight could be realized by another cycle of selection. Four clones from each of 72 maternal half-sib families constituting the cycle four population were evaluated for late blight resistance in replicated field trials in Pennsylvania in 2015 and 2016. The experimental design was a randomized complete block design with two replications each year. P. infestans US23 genotype was used in inoculations each year. Area under the disease progress curve (AUDPC) was calculated based on visual assessment of foliar disease five times late in the season each year and subjected to statistical and genetic analyses. Mean AUDPC in the cycle 1, 2, 3, and 4 populations was 652, 556, 276, and 173, respectively. Narrow-sense heritability for resistance decreased in the cycle 4 population (h2=0.54) as compared to prior populations (0.77