In vivo induction and characterization of polyploids in gerbera daisy

Cultivated gerbera (Gerbera hybrida; Asteraceae) is an economically important flower worldwide. It is also used as a model plant for studying flower development and understanding biosynthesis of secondary metabolites. Genetic variation in cultivated gerbera is narrow; therefore, increased genetic variation is much needed for further improvement of gerbera. Polyploidization has played an extremely important role in the diversification, evolution, domestication and breeding of many plant species. In this study, tetraploids were induced by treating the apical meristems of gerbera seedlings with colchicine. The nuclear DNA content of tetraploid gerbera was increased to 10.41 pg/2C from 5.22 pg/2C. Induced tetraploids had larger, fewer stomata and wider, thicker leaves than diploids, resulting an increased leaf index. With tetraploidization, flower scapes became thicker, flowers were larger, ray florets became wider, and the center eye (composed of disc florets) was larger. Induced tetraploids showed lower but still high pollen stainability and are expected to be quite fertile and be able to serve as parents for production of triploids. Some of the morphological changes associated with induced tetraploidy, including larger flowers, thicker ray florets, larger eyes and/or thicker scapes, will be beneficial for gerbera flower quality and vase life, while other changes such as stomatal size and density and thicker leaves may change and improve gerbera tolerance to stresses. Induced gerbera tetraploids may be valuable for breeding, genetic research and increasing genetic diversity in gerbera.