Genetic Mapping And Molecular Markers Development Of Tuber Shape Gene In Potato

In this study, a diploid F1 tuber shape segregated population was used to develop molecular markers and construct a genetic map of Ro gene region that determine round-shape tuber using the genome sequence information and bulked segregation analysis(BSA). In order to develop molecular markers that can be applied in potato marker-assisted breeding, the markers were verified on tetraploid clones. The main results achieved are as follows:1. Tuber shape of segregation population has been phenotyped for four consecutive years. The phenotyping results of tuber shape segregation population derived from female parent 10618-01 with long-shape tuber and male parent 320-02 with round-shape tuber showes that the observed segregation of round-shape and long-shape individuals fits a 1:1 ratio by Chi-square test, which indicates tuber shape was controlled by a major gene. However, we also noted that the distribution of tuber shape phenotypes was not clearly bimodal with the two peaks coinciding with tuber shape index of 10618-01(long-shape parent) and 320-02(round-shape parent), instead it skewed towards round tuber shape, suggesting tuber shape may be conferred by Ro and some other loci with small effects.2. Seventeen molecular markers linked to potato tuber shape were developed. Based on the genome sequence information and combining with bulked segregation analysis, we developed 17 markers linked to Ro gene. Six of these markers are as repulsion phase to round-shape tuber.3. A genetic map of Ro gene region was constructed. We used 17 molecular markers to constructe Ro gene genetic map combined with phenotype results. The genetic map spans 44.7cM and the average genetic distance among markers is 2.63 cM. Ro was mapped in 2.8cM interval between 542-CAPS and 1137-CAPS markers, equating to 460 kb physical distance. 1137-CAPS was the nearest marker with 0.2cM distance.4. A molecular marker can be applied to marker-assisted selection for round-shape tuber in potato breeding was developed. Through verifying 17 markers we developed in 53 different tetraploid lines, we obtained a marker, 1137-CAPSVI, which is tightly linked to round-shape tuber in cultivated potato. The results showed that the similarity between round-shape phenotype and 1137-CAPSVI was 91.42%. Therefore, 1137-CAPSVI can be applied to marker-assisted selection for round-shape tuber in potato breeding.