No Requirement of Vernalization for Flower Formation in Ri-Transformed Cichorium Plants.

Abstract

Hairy roots of Cichorium intybus L. cv. Witloof were induced by inoculation with Agrobacterium rhizogenes harboring different types of Ri plasmids (pRiA4, pRi15834 and pRi8196). Whole plants were regenerated from the hairy roots by culturing them on a modified Murashige and Skoog's medium containing BA (1 mg/l). Transformation was confirmed by the presence of agropine and mannopine in the hairy roots and of internal fragments of the T-DNA of Ri plasmid in the leaves of the regenerated plants. These tansgenic plants flowered without vernalization under a long-day condition, but normal (nontransformed) plants did not show any flower bud formation under the same condition. Ro1C gene was cloned into T-DNA of a disarmed mini Ti plasmid (pBI101) and transformation was achieved by the leaf disc method. The transgenic plants with rolC gene flowered without vernalization under a long-day condition.