Detection of quantitative trait loci for leaf traits in chrysanthemum

To identify quantitative trait loci (QTL) controlling leaf traits and to provide some reference for future molecular marker-assisted selection and breeding for leaf traits in chrysanthemum, QTL analyses were conducted for three leaf traits: leaf length (LL), leaf width (LW), and the ratio of leaf length to width (LL:LW). Phenotypic data were collected over 2 years in a segregating F-1 population of 142 hybrids of 'Yuhualuoying' X 'Aoyunhanxiao' and analysed using previously published sequence-related amplified polymorphism (SRAP)-based maps. A total of 12 additive QTLs were identified for the three leaf traits. Each QTL accounted for between 5.8% and 13.4% of the observed phenotypic variation. Seven QTLs were detected at the same genomic regions in both years, indicating that they were stable over different environments. The tight causal linkages between the different QTLs controlling LL and LW on linkage group Y14 of the 'Yuhualuoying' map and on linkage group A13 of the 'Aoyunhanxiao' map may account for the significant phenotypic correlation between the two leaf traits. In addition, three epistatic QTLs for LL and LW accounted for 2.1 - 11.8% of the phenotypic variation in these traits. The results obtained in the present study add new knowledge and a deeper understanding of the genetic basis of leaf traits in chrysanthemum, and may be valuable in future breeding programmes to develop chrysanthemum cultivars that exhibit more desirable leaf traits.