Quantitative trait locus analysis of leaf morphological characters, yield-related traits, and secondary metabolite contents in Eucommia ulmoides.

Eucommia ulmoides is cultivated for the production of eucommia rubber and Chinese herbal drugs. Molecular breeding methods, such as marker-assisted selection (MAS), have the potential to improve the efficiency of E. ulmoides breeding. Quantitative trait locus (QTL) analysis was applied to identify marker-trait associations for E. ulmoides using an F1 mapping population of 152 individuals derived from a cross between the wild genotype Xiaoye and the cultivar Qinzhong No. 1. A total of 78 QTLs were identified for 12 leaf traits involving morphology, yield, and secondary metabolites. Phenotypic variance explained by individual QTLs ranged from 10.4 to 53.3%. Fifteen QTL clusters, each harboring loci controlling at least two leaf traits, were detected across nine linkage groups. Co-location of these QTLs may be due to pleiotropy or linkage. Three main QTL regions for secondary metabolites were consistently identified each year. QTL information from this study furthers our understanding of the genetic architecture of these economically important traits and of MAS in E. ulmoides breeding.