EFFECT OF ROL GENES FROM AGROBACTERIUM-RHIZOGENES TL-DNA ON NICOTINE PRODUCTION IN TOBACCO ROOT CULTURES

Transgenic root lines were induced by inoculation of Nicotiana tabacum cv. Xanthi leaf sections with a disarmed strain of Agrobacterium tume faciens harbouring the rolA, rolB and rolC genes either together or si ngly cloned in the binary vector pPCV002. The transgenic root lines gr ew in the absence of added phytohormones and their growth pattern and nicotine biosynthesis capacity were followed. Striking differences in nicotine production were shown by the four types (rolABC, rolA, rolB a nd rolC) of transgenic root lines. While the rolC gene was responsible for a high stimulation of alkaloid production by increasing growth, t he rolA gene stimulated this production mainly by a direct effect. The presence of rolA, rolB and rolC together dramatically enhanced the gr owth rate and nicotine production, which showed that the effect of the se three rol genes was synergistic. We suggest using roots transgenic for rol ABC genes to improve the production of secondary metabolites i n vitro. The possible advantages of these transgenic roots over the ro ots transformed by a wild strain of Agrobacterium rhizogenes are also considered.