Construction Of A Genetic Linkage Map In Chinese Cabbage×Turnip Based On SSR And InDel Markers

Chinese cabbage(Brassica rapa ssp. pekinensis) is one of the most important vegetable crops in China. A detailed genetic linkage map offer the possibility of developing genetic studies on various agronomic traits through the localization of major genes and quantitative trait loci(QTLs), helping breeding programs with marker-assisted(MAS), as well as for comparative genomics and map-based cloning. Cruciferae Brassica turnip is the biennial herbs plant which can form a fleshy root, with a lot of important genetic characteristics, in particular the character of the late bolting which provides excellent breeding genetic source for breeding late spring and summer cabbage varieties. Constrution of a molecular genetic map in Chinese Cabbage X Turnip can not only locate and use of the late bolting gene of turnip, but also provide basis for the formation of Chinese cabbage leaf ball and stem inflation research. A genetic linkage map in Chinese Cabbage X Turnip based on SSR and InDel markers was constructed in this study in order to comparison with reference maps. Marker analysis was performed on80double haploid(DH) lines obtained by microspore culture from F1progeny of two homozygous parents:BY(an extra-early bolting Chinese cabbage line) and MM(an exra-late bolting European turnip line).The molecular genetic map is fundamental for fine-mapping and molecular ckone of important traits in Chinese cabbage and turnip.1. Markers were screened by two parents and F1. Out of265SSR primer pairs that were screened,87(32.8%) amplified polymorphic products between the two parents. And of the400InDel markers,96(24%) InDel markers showed polymorphism between2parents. All the markers were distributed in10linkage groups, that will provide basis for construction of Chinese cabbage map based on InDel and SSR markers.2. A DH population derived from the F1between Chinese cabbage BY and Turnip MM was employed to construct the genetic linkage map based on SSR and InDel markers.87SSR and96InDel markers showed polymorphism and were analyzed in DH population, in addition,55previously mapped SSR markers were also used in mapping.202markers were integrated into10groups. It covered a total of925.7cM with an average interval of4.7cM. The number of markers in each linkage group varied from14to28, the length from66.1cM to113.3cM and the average interval from3.2cM to8.1cM and. The202markers were grouped into10linkage groups at LOD>3.0in the consensus map. The remaining36markers were not grouped into any linkage groups. The molecular genetic map will provide basis for gene localization in Chinese cabbage and turnip.3. A total of54.9%(111of202loci) of the markers showed significant segregation distortion in this population (p<0.05). Different numbers of distorted loci were detected in each parent,79(71.2%) markers showed distorted segregation were bias for BY, and32(28.8%) were bias for MM.4. Four loci variation were detected among DH lines in183markers showed polymorphism between two parents. The variation rate is range from28.75%to32.5%.