In vitro culture of four medicinal asteraceae species for Agrobacterium rhizogenes transformation

Hairy roots produced by infection with Agrobacterium rhizogenes are phenoty pically altered and show an overproduction of secondary compounds. Four Ast eraceae species were tested: Artemisia annua (with proven antimalarial acti vity), Calendula officinalis (antiseptic), Mikania glomerata (a Brazilian p lant used for respiratory disease treatment) and Helianthus annuus (sunflow er with tonic and anti-neuralgic activities). Seeds of Artemisia annua, Cal endula officinalis and Helianthus annuus were surface disinfected with 25% NaOCl solution for 15 min., and Mikania glomerata stems were surface disinf ected with 25% NaOCl solution for 30 min. Sterile and viable explants were mantained in complete Murashige & Skoog's culture medium and subcultured af ter 28 days. Once established in culture, the explants of all species were inoculated with Agrobacterium rhizogenes strains 8196 and 15834. Only Artem isia annua showed a positive hairy root response. These roots were excised and cultured "in vitro". In order to confirm the transgenic character of th e hairy roots a Southern Blot hybridization was carried out. The culture pr otocols established for the other three species were used to obtain explant s for further transformation tests.