| Pear(Pyrus L.) is one of the most ancient cultivated fruit trees in our country, and Chinese pear has played an important role in the world on cultivated area and output for successive years. In recent years, great progress has been made in the breeding of improved varieties through traditional breeding methods, but research on genetic map construction and its application is relatively backward compared to apples, peaches, grapes and other fruits. In this study, 165 F1 progenies derived from the cross ‘Red Clapp Favorite'(Pyrus communis L.) x ‘Mansoo'(Pyrus Pyrifolia Nakai), were selected to construct the parents linkage map respectively by using SSR markers. Besides, based on the investigated growth traits in the population and fruit traits in part of the population, combined with the constructed map, the QTL of some related traits was analyzed by using interval mapping, providing a foundation for the gene mapping of the related traits and the molecular marker assisted breeding. The main results were as follows:(1)The authenticity of 167 individuals in F1 population which derived from the ‘Red Clapp Favorite' x ‘Mansoo' were identified using the SSR molecular marker technology according to the 5 pairs of selected SSR primers, and 2 non-parent true hybrids were eliminated from the population, which would provide real materials for the future research, and lay a reliable basis for constructing high quality map.(2)909 pairs of SSR primers from different sources(526 pairs from pear and 283 pairs from apple that have been published, and 100 pairs were developed from the pear transcriptome by our team) were preliminarily screened out through PCR technique. The data showed that the effective amplification ratio was at 79.54% between the parents, polymorphism at 60.84%, and 22.77% of SSR primers conformed to the drawing.(3)The screened primers in the population were verified, and by using JoinMap4.0 software, the genetic linkage map were constructed. Female genetic map was constructed by 141 markers which distributed on 17 linkage groups and spanned 757.34 cM in genome with an average distance of 5.37 cM between markers, and the length of each linkage group containing 4-16 makers was 18.80 cM-63.29 cM; Male genetic map was constructed by 153 markers which distributed on 19 linkage groups and spanned 1149.43 cM in genome with an average distance of 7.51 cM between markers, and the length of each linkage group containing 3-17 markers was 5.67 cM-119.41 cM.(4)According to the parents linkage maps, the Quantitative Trait Loci(QTL) linked to 5 agronomic traits(tree diameter, leaf length, leaf width, petiole length, leaf shape index) was analyzed with MapQTL5.0 software using interval mapping method, and it was finally found that there were totally 21 QTLs, and 2-7 QTLs on each agronomic trait.(5)With the screened 207 pairs of SSR primers conforming to the drawing, the genetic linkage map of 81 plants with fruits was reconstructed. The data showed that, in the genetic map, there were 187 markers which distributed on 18 linkage groups and spanned 964.82 cM in genome with an average distance of 5.16 cM between markers, and 5-18 markers on each linkage group.(6)Combined with the new linkage map of the plants with fruits, the QTL linked to 5 agronomic traits(mass of single fruit, transverse diameter of fruit, vertical diameter of fruit, stem length of fruit and core size of fruit) was analyzed with MapQTL5.0 software using interval mapping method, finally finding that there were 4 QTLs related to 3 agronomic traits(mass of single fruit, transverse diameter of fruit and vertical diameter of fruit), and no QTLs related to the stem length and core size of fruit. |
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