| One breeding method for potato (Solanum tuberosum subsp. tuberosum) is using wild species. This method could be more efficient if the introgression of genes from these species were monitored with molecular markers. Furthermore, the use of molecular markers allows the dissection of quantitative traits into discrete genetic factors. The objective of this research was to perform quantitative trait loci (QTL) analysis on two tuber traits in potato: specific gravity and dormancy. Two diploid populations were constructed from heterozygous self-incompatible parents. These two populations, TRP 132 (127 individuals) and TRP133 (110 individuals) have a common maternal parent and combine genomes of Solanum tuberosum (haploid), S. chacoense, and S. phureja. A preliminary analysis using isozymes was performed. QTLs were determined by one-way analyses of variances for each locus by trait combination (P {dollar}<{dollar} 0.05). Epistatic interactions were detected through two-way analyses of variance. Further studies focused on TRP133, which was characterized for 10 isozyme loci, 44 RFLPs and 63 RAPDs. Eighty-seven loci segregating from the female parent were utilized to construct a linkage map comprising 10 of the 12 chromosomes in the genome. For dormancy, 6 QTLs were identified that explained 57.5% of the phenotypic variation for the trait. Specific gravity was evaluated in 3 environments. QTLs were mapped separately for each location and in combination. A total of 10 QTLs on six chromosomes were identified. The numbers and effects of QTLs detected varied across environments, and they explained from 39% to 45% of the phenotypic variation for the trait. Using the average data a multilocus model was developed. This gives consistent results when tested across environments, and may be valuable for marker-assisted selection. This research developed the basic methodology for QTL analysis in potato which is now available for future studies with other traits and germplasms. |
