Identification of quantitative trait loci for branching traits of spray cut chrysanthemum

Branching is an important horticultural trait that influences plant architecture and production of cut chrysanthemum; however, its genetic determinism is poorly understood. In this study, an F-1 mapping population derived from a cross between two spray cut chrysanthemum cultivars was used to determine QTL underlying branching. The branching traits in the F-1 mapping population exhibited over-parent segregation and relatively high heritability (0.68-0.92). Based on the branching traits across two consecutive years, 16 additive QTL, including five QTL for primary branch number, each four QTL for branch height, and branch angle, and three QTL for primary branch length, were identified, with each accounting for 6.9-24.4 % of the phenotypic variation. Of these, four QTL expressed stable, located in the same genomic regions across two consecutive years. Results from this study add new understanding of the genetic basis of branching in spray cut chrysanthemum, and the putative major QTL detected here are valuable for future breeding cut chrysanthemum that exhibits desirable branching type.