SRAP-based mapping and QTL detection for inflorescence-related traits in chrysanthemum (Dendranthema morifolium)

Chrysanthemum (Dendranthema morifolium) is an economically important ornamental species and comprises a large proportion of the flower industry in south-east Asian and European countries. In this study, a segregating population of 142 F-1 progeny of the cross between the two chrysanthemum cultivars 'Yuhualuoying' and 'Aoyunhanxiao' was used to construct two separate genetic linkage maps via a double pseudo-testcross mapping strategy. Genotyping was performed using 500 SRAP primer combinations, of which about 50% were informative. This allowed the definition of 896 SRAP loci, of which about 23% showed some segregation distortion. The 'Yuhualuoying' map consisted of 333 testcross markers arranged into 57 linkage groups (LGs). It covered > 1,900 cM with a mean inter-marker distance of 6.9 cM. The map constructed from 'Aoyunhanxiao' comprised 342 test cross markers arranged into 55 LGs. It spanned nearly 1,900 cM, with a mean inter-marker distance of 6.6 cM. The markers were distributed rather uniformly along both maps. A quantitative trait loci analysis was conducted to investigate the pattern of inheritance of three inflorescence traits. This led to the detection of 12 putative loci at a LOD score > 2.5, of which four each specified flower diameter, ray floret layer number, and ray floret length. This study provides molecular mapping information on marker-assisted selection programs for the improvement of multiple traits of interest.