Linkage map construction and QTL analysis for Betula platyphylla Suk using RAPD, AFLP, ISSR and SSR

A linkage map for Betula platyphylla Suk was constructed based on RAPD, ISSR, AFLP and SSR markers by a pseudo-testcross mapping strategy. A F₁ segregating population including 80 progenies was obtained from the cross between two superior trees selected from Qinghai and Wangqing provenance, respectively. The paternal map was constructed with 282 markers consisting of 14 major and 15 minor (5 triplets and 10 doublets) linkage groups and spanning 1131 cM at an average distance of 4.0 cM between adjacent markers. The maternal map has 277 markers consisting of 15 major and 8 minor (5 triplets and 3 doublets) groups covering 1288 cM at an average distance of 4.6 cM between adjacent markers. In the same pedigree we investigated association of genetic markers with seedling stem height and circumference. The composite interval mapping was used to detect the number of quantitative trait loci and their position on the genetic linkage maps. Three QTLs (one on the male map and two on the female map) were found explaining 13.4%, 17.5% and 18.8% of the trait variation, respectively.