Study of the Agrobacterium rhizogenes-mediated transformation of Paulownia fortunei

摘要

Different seedling parts of Paulownia fortunei were used to induce hairy roots when cultured on MS basal medium after infection by the Agrobacterium rhizogenes strain, BCRC 15011. Lamina (middle 1/3 section) explants produced transformed roots at a higher frequency (85.71%) compared to lamina with a petiole (70%), internode (30.55%), or leaf apex (33.33%). Hairy roots exhibited vigorous growth and abundant lateral branching on hormone-free medium. The optimized culture conditions for hairy roots were examined by varying the factors of salt concentration in the medium, type and amount of carbohydrates, and illumination conditions that influenced root growth and morphology. TDZ (thidiazuron) was the most effective cytokinin for inducing green calli. Adventitious shoots were occasionally induced from these calli that were initially treated with a high dosage of TDZ or TDZ + NAA (naphthaleneacetic acid) and then transferred onto medium containing NAA (0.5 mu M) and TDZ (<= 5 mu M). Transformation events in hairy roots and calli derived from these hairy roots were comfirmed by identification of a known DNA sequence of a rolC gene fragement from the examined transformants.