Peculiarities of the Transformation of Asteraceae Family Species: The Cases of Sunflower and Lettuce

The Asteraceae family is the largest and most diversified family of the Angiosperms, characterized by the presence of numerous clustered inflorescences, which have the appearance of a single compound flower. It is estimated that this family represents around 10% of all flowered species, with a great biodiversity, covering all environments on the planet, except Antarctica. Also, it includes economically important crops, such as lettuce, sunflower, and chrysanthemum; wild flowers; herbs, and several species that produce molecules with pharmacological properties. Nevertheless, the biotechnological improvement of this family is limited to a few species and their genetic transformation was achieved later than in other plant families. Lettuce (Lactuca sativa L.) is a model species in molecular biology and plant biotechnology that has easily adapted to tissue culture, with efficient shoot regeneration from different tissues, organs, cells, and protoplasts. Due to this plasticity, it was possible to obtain transgenic plants tolerant to biotic or abiotic stresses as well as for the production of commercially interesting molecules (molecular farming). These advances, together with the complete sequencing of lettuce genome allowed the rapid adoption of gene editing using the CRISPR system. On the other hand, sunflower (Helianthus annuus L.) is a species that for years was considered recalcitrant to in vitro culture. Although this difficulty was overcome and some publications were made on sunflower genetic transformation, until now there is no transgenic variety commercialized or authorized for cultivation. In this article, we review similarities (such as avoiding the utilization of the CaMV35S promoter in transformation vectors) and differences (such as transformation efficiency) in the state of the art of genetic transformation techniques performed in these two species. Instituto de Biotecnología Fil: Darqui, Flavia Soledad. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; Argentina Fil: Darqui, Flavia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Radonic, Laura Mabel. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; Argentina Fil: Radonic, Laura Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Beracochea, Valeria Cecilia. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; Argentina Fil: Beracochea, Valeria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Hopp, Horacio Esteban. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; Argentina Fil: Hopp, Horacio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fil: Hopp, Horacio Esteban. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular; Argentina Fil: Lopez Bilbao, Marisa Gisela. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; Argentina. Fil: Lopez Bilbao, Marisa Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina