Chrysanthemum Biotechnology: Quo vadis?

Chrysanthemum is globally the second most important ornamental in terms of socioeconomic importance. Even though the vast range of flower colors, shapes and forms were initially created using conventional and mutation breeding, transgenic strategies are now more frequently used with Agrobacterium-mediated transformation being the most popular form of introducing foreign genes into chrysanthemums. Even so, transformation efficiency remains dependent on cultivar and regeneration procedure. Transgenic molecular breeding has seen the introduction of important traits such as novel flower color and form and plant architecture, prolonged cut-flower vase-life, resistance to biotic stresses such as viruses/viroids, pathogens and insects. However, chimerism and transgene silencing continue to be limiting factors. Transgenic strategies, despite opening up new avenues for creating new cultivars with improved agronomic and horticultural traits, may be limited due to the risk of transgenic pollen escaping into the wild.