Submitted to: American Journal of Potato Research
Publication Type: Abstract Only
Publication Acceptance Date: May 6, 2011
Publication Date: February 1, 2012
Citation: Haga, E., Jansky, S.H., Halterman, D.A. 2012. Characterization of early blight resistance derived from the wild potato species Solanum berthaultii. American Journal of Potato Research. Paper No. 61.
Early blight (EB), caused by the fungal pathogen A. solani, is a ubiquitous potato disease of world-wide significance. Fungicides are the main method of control, as cultivated varieties offer only a few sources of moderate resistance, most of which are associated with late maturity. Strong levels of resistance have been identified in the wild potato species Solanum berthaultii (2n = 2x = 24) using a detached leaf assay, and breeding efforts to introgress this resistance into cultivated potato offer promise in increasing the sustainability of potato production. In order to understand the genetic basis of resistance in this species, 12 breeding populations were developed through interspecific hybridization of three S. berthaultii individuals to four cultivated haploids (2n = 2x = 24) of S. tuberosum. These populations were evaluated for disease under natural field conditions without fungicides for two seasons in a major potato production area of Wisconsin. Field resistance was rate-limiting, wide-ranging, and continuously distributed, suggesting quantitative inheritance of this trait. Repeatability of population means was low (0.1644 – 0.2398), implying segregation of many genes for EB resistance. However, there were still many indications of strong potential for resistance breeding with this species, including the presence of transgressive segregants within each population and the detection of significant differences among populations. Combining ability analyses revealed that the choice of cultivated parent, not the wild parent, caused these differences among populations. Among the cultivated parents examined, US-W973 had the best combining ability for EB resistance, while US-W4 had the worst.