| Quantitative trait is complex and regulated by polygenes, which are called QTL. Agronomic traits are basically quantitative traits, including reproductive behavior, economic yield, resistance and so on. Traditional genetic mapping by molecular markers is labour-intensive and time-consuming. Therefore, it is imperative to adopt new strategies. Potato(Solanum tuberosum L.) is the fourth largest food crop in the world. The promotion and implementation of potato food strategy makes the potato industry play a more important role in the national economy and the people’s livelihood. Dormancy is a main factor affecting the potato cultivation and utilization, but the mechanism of tuber dormancy is still largely unkown. Therefore, the in-depth study on genetic mechanism of tuber dormancy has important practical significance for potato production and processing.Diploid potato were used for this study. Main results are as follows: 1. Initial location of dormancy related QTLsIn this study, we counted seven groups of potato tuber dormancy. By marker polymorphism analysis, we detected eight loci in chromosomes 3, 5 and 6 of male map, as well as ten loci in chromosomes 2, 5, 6 and 10 of female map. The phenotypic contribution rate of loci is 7.3%-23.2%, with the maximum located in chromosome 5. DorB5-2 was detected by three groups, DorE5-3 and DorE6-2 were detected by two groups respectively. 2.BSR-seq(RNA-seq combined with BSA)Based on the comprehensive analysis of five groups of data, we selected 24 long dormant plants and 24 short dormant plants from EB group, to build four pools for RNA-seq analysis. Using potato DM genome as a reference, we searched SNPs of these pools, and calculated the SNP-index and Δ(SNP-index) between male and female parents, long and short pools. The Δ(SNP-index) frequency graph suggests that chromosomes 1, 2, 3, 5, 6 and 7 may exist dormancy related QTL sites. 3. Marker development and relocalization of dormancy related QTLsBy analysis of rough map and BSA-seq, we designed nine SNP markers and fourteen Indel markers in chromosomes 1, 2, 3, 5, 6 and 7, and analyzed the polymorphism of the EB population. As a result, we got twenty-six polymorphic bands and built a new linkage map using the mapping software Joinmap4.0.Compared with the original map, the length of linkage groups of the male does not have a significant change. Nevertheless, chromosome 2 and 3 increase to 87.7 cM and 25 cM, individually. We thus could develop three new markers in chromosome 2 of the female map. We then carried out Kruskal-Wallis analysis between markers and phenotype data by using of software MapQTL. Results showed that: among 26 polymorphic loci, 12 are significant at α=0.05 level. These loci locate in the stable interval of initial location, which shows that these markers have a correlation with dormancy.By relocalization analysis, we detected eight loci in male chromosomes 3, 5 and 6 and 14 sites in female chromosomes 2, 3, 5, 6, 9, 10 and 11. The contribution rate of phenotypic variation ranges from 7.9% to 23.8%, with the maximum located in chromosome 5, which stays the same with previous analysis. QTLs DorE3-2, DorE5-2 and DorE6-2 were detected by two groups of data respectively.Compared with the initial location, the interval of 2-LOD of five loci in the male map narrows down. In addition, the female map adds five loci, QTLs DorE6-2’s interval is decreased. The loci phenotypic variation contribution rate is slightly increased. Markers Indel3-6 and SNP5-2 were detected, indicating that these markers are related to dormancy. New markers influenced the location results, that some site positioning intervals were narrowed down and more environmental loci were detected, which boost the reliability of mapped QTLs related with tuber dormancy. |
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