HORTICULTURAL CHARACTERISTICS OF TRANSGENIC TOBACCO EXPRESSING THE ROLC GENE FROM AGROBACTERIUM-RHIZOGENES

'Wisconsin 38' tobacco (Nicotiana tabacum L.) leaf discs were transfor med with the disarmed Agrobacterium tumefaciens strain EHA101 carrying the rolC gene from A. rhizogenes (Oono et al., 1987) and NPT II and G US genes. Shoots that regenerated on kanamycin-containing medium were confirmed as transgenic through GUS assays, polymerase chain reaction (PCR), Southern blot analyses, and transmission of the foreign genes t hrough the sexual cycle. Transgenic plants were as short as half the h eight of control plants; were earlier flowering by up to 35 days; and had smaller leaves, shorter internodes, smaller seed capsules, fewer s eeds, smaller flowers, and reduced pollen viability. The number of see d capsules, leaf number, and specific root length were similar between transgenic and control plants. Transgenic clones varied in the expres sion of the rolC-induced growth alterations as did the first generatio n of seedlings from these clones. Such differences suggested the poten tial for selecting for different levels of expression. Transformation with the rolC gene presents a potentially useful method of genetically modifying horticultural crops, particularly for flowering date, heigh t, and leaf and flower size.