Resistance to common scab developed by somatic hybrids between Solanum brevidens and Solanum tuberosum

Abstract

Potato is one of the most important crops in the world and the common scab caused by Streptomyces species is a serious disease. To control the disease, agronomical, chemical and biological methods are commonly applied; however, the introduction of resistance into cultivated potatoes has been considered to be the most promising approach. Therefore, in this study, the authors identified resistant breeding lines derived from somatic hybrids that were produced by protoplast fusions between Solanum brevidens and Solanum tuberosum. Initially, in vitro assay was applied to select resistant interspecific hybrids, but field assays were also performed to develop resistant breeding lines and populations. Although chromosome number and crossability were not completely recovered back to the cultivated potatoes on somatic hybrids and backcross populations, breeding lines and populations with resistance to common scab that could be used for further breeding were developed. Finally, four BC2 populations were selected and tested for resistance to the common scab and for productivity. There were variations in resistance to the common scab within each line and in productivity between lines, but the average percentages of tuber surface area with disease symptom in BC2 lines were approximately 85% and 46% less than the commercial parent controls, ‘Dejiam’ and ‘Superior’, respectively and the productivities of two populations recovered by 80–103% and 90–115% relative to ‘Dejiam’ and ‘Superior’, respectively. The results obtained in this study may contribute genetic analysis and further breeding for resistance to the common scab.