Use of a Disarmed Ri Plasmid Vector in Analysis of Transformed Root Induction

Abstract

Nicotiana glauca, N. tabacum, Solanian dulcamara and S. nigrum were transformed by Agrobacteriun rhizogenes strain BN1010 (TL−TR+). The TR-DNA stimulated agropine-positive root induction and was transformation competent in the absence of the TL-DNA. An unusual pattern of root induction was seen when stem explants were inoculated with this strain; occasionally, agropine-positive roots were induced at the inoculation sites, but prolific agropine-negative roots were formed in profusion down the stems. The utility of BN1010 as an efficient co-integrating vector was demonstrated by the separate transfer of a fragment containing rol ABC (BN1010:: pEM15) and of a chimeric nopaline synthase-kanamycin resistance gene (BN1010:: Neo) into plants. Root cultures of S. dulcamara transformed with BN1010:: Neo had an unusual, positively geotropic phenotype. Strain BN1010:: pEM15 (rol ABC+D−TR+) incited more roots down stem explants than strain A4T. This indicates that rol D may act to suppress agropine-negative root production in N. glauca and N. tabacum.