Chrysanthemum is the second most important cutflower in the world, with The Netherlands as one of the leading countries in breeding chrysanthemum varieties. Improving the breeding efficiency in Chrysanthemum has proven rather difficult because of its (segmentalallo) hexaploid outcrossing nature.
Furthermore, so-called decorative chrysanthemums are popular nowadays, but the majority of these varieties suffer from (partial) male or female sterility. Hence, it is difficult to get enough seeds from crossings of these flower types and colors, resulting at best in small populations to select from. Recent advances in genomics and molecular biology provide breeding tools to solve these problems and to accelerate genetic gains. We aim to understand the relation between the development of the flower and seed set in the composite Chrysanthemum and to develop tools to optimize breeding.
In general, research on flower development is done in Arabidopsis, Antirrhinum and Petunia, and much less is known about flower development in composites. Most knowledge in composites derives from research in Gerbera, and these studies have focused on floral organ specification and outgrowth, and not on seed set. Novel in this project is that we will study the relation between flower shape (ray- disc flowers) and reproductive organ development. We aim to identify genes that play a role in reproductive organ development, and fertility, followed by detailed functional analyses of the selected genes. The results will be of fundamental interest, both for understanding flower development in composites, such as Chrysanthemum, as to develop knowledge about the relationship between reproductive organ development and seed set in flowering plants. In addition, we aim to translate the results on diploid wild Chrysanthemum members, which have an excellent fertility, to the commercial hexaploid varieties, and develop tools that are useful for research in polyploid species in general. Altogether, the activities in this project will have impact far beyond the ornamental Chrysanthemum, because many important food crops, such as lettuce and chicory are composites, and breeding of these species will benefit from the knowledge and tools generated in this project.