Construction Of A Molecular Genetic Linkage Map And QTL Analysis Of The First Female Flower Node Trait In Cucumber (Cucumis Sativus L.)

A high-density molecular genetic linkage map holds an important status in cumcumber breeding. It helps molecular assisted selection, QTL mapping and map based gene cloning. In our research, a molecular genetic linakage map of cucumber were constructed by taking parents U4 ,Hm60-1 and their cross F2 population as materials. Parent U4 is a wide cultivar which found in china, Hm60-1 is a common cultivar which cultivated widely. The parents are different from each other distinctly in plant size, branches, the first female flower node, disease resistance et al.The AFLP markers, SRAP markes, SSR markers were employed in the construction of the genetic linkage map, and Joinmap 3.0 software was used to construct the map in this study. The first female flower node trait was mapped on this linkage map by QTL mapper 4.0 software. The main results of this study were as follows:1. 159 polymorphic primer combinations between the two parents were found from 259 AFLP primer combinations, the polymorphic ratio was 61.4%; 71 polymorphic primer combinations between the two parents were found from 75 SRAP primer combinations, the polymorphic ratio was 94.6%; 14 polymorphic primer combinations between the two parents were found from 113 SSR primer combinations, the polymorphic ratio was just 12.4%.2. The polymorphism of the AFLP markers, SRAP markers, SSR markers were analyzed. 53 AFLP primer combinations generated 160 polymorphic locus, 3.2 per primer combination; 20 SRAP primer combinations generated 58 polymorphic locus, 2.9 per primer combination; 14 SSR pimer combinations generated 14 polymorphic locus, 1 per primer combination. The polymorphism is AFLP>SRAP>SSR.3. Using Joinmap3.0 software, a molecular genetic linkage map which included 10 linkage groups and contained 112 AFLP markers, 39 SRAP markers, 8 SSR markers respectively was obtained. This map covering the cumcumber genome 743.11cM, the average distance between two markers is 4.67cM, which can be used for QTL mapping.4. Mapping of the quantitative trait loci of the first female flower node was executed by Interval mapping in QTL mapper 4.0 software. The total 8 QTLs were found on the map, named them as ff1, ff2, ff3, ff4, ff5, ff6, ff7, ff8. ff1, ff2 located on linkage group2; ff3, ff4 located on linkage group3; ff5, ff6 located on linkage group6 and ff7, ff8 located on linkage group7. All of the QTLs showed positive additive effect except ff3, ff4 locus which showed negative additive effect.