Marker Associations For Plant Architecture In a Polyploid Ornamental: A Case Study On Shoot Branching In Chrysanthemum

The branching pattern of a plant is of special interest in the production of cut flowers of chrysanthemum. As side shoots compete with the primary stem and flower for nutrients and assimilates, they reduce persistence and size of the terminal flower. Therefore, side shoots have to be removed by hands with high labour costs. The development of non-branching varieties via marker assisted selection could solve this problem.

We used two different methods to identify markers linked to reduced shoot branching in the hexaploid ornamental chrysanthemum. On the one hand we detected allelic variants (SSCPs) of the strigolactone pathway genes CCD7 and CCD8 in a pool of 76 chrysanthemum varieties, that were significantly associated with branching variation. On the other hand we used a bulked segregant strategy in a segregating F1 population of 160 individuals. Screening 540 AFLP-primercombinations we identified 2 markers significantly linked to the branching rate.

By transferring these markers into sequence-characterized amplified region (SCAR) markers breeders could easily select for low branching varieties at the very beginning of the breeding process of chrysanthemum cut-flowers.