Marigold Biotechnology: Tissue Culture and Genetic Transformation

Members of the Tagetes genus include important floricultural (cut-flower) and ornamental (pot and garden) crops, as well as plants of medicinal and ethno-pharmacological interest. Despite the use of many of these plants in the extraction of important secondary metabolites and essential oils, the greatest biotechnological emphasis has been on their in vitro tissue culture and micropropagation. Few studies have been conducted on genetic transformation, with those primarily focused on increasing yield of compounds in plants. However, the application of genetic transformation methodology requires the development of efficient techniques, not only for the transfer of foreign genes into plant cells, but also for the regeneration of whole, fertile plants from the transformed cells. Thus, the development of suitable methods for regeneration is one of the main prerequisites for genetic improvement by biotechnologic means. The purpose of our review is to describe the approaches, via organogenesis or embryogenesis, that have been applied to regenerate whole marigold (Tagetes erecta L.) plants and the current status of targeting genes, whether via Agrobacterium tumefaciens or biobalistics. The advances, applications and limitations of marigold biotechnology are discussed. _____________________________________________________________________________________________________________