FACTORS AFFECTING AGROBACTERIUM-TUMEFACIENS-MEDIATED GUSA EXPRESSION AND OPINE SYNTHESIS IN GLADIOLUS

Five tumorigenic strains of Agrobacterium tumefaciens were used to ino culate corms, cormels, plants grown in vitro, and seed-derived seedlin gs of several cultivars of Gladiolus. Tumors formed on 12% of the plan t tissues inoculated, and 1% of these tumors synthesized either octopi ne or nopaline. A. tumefaciens-mediated beta-glucuronidase (GUS) expre ssion showed 0.5% and 3.5% GUS expression for plants grown in vitro an d regenerable callus, respectively. GUS expression ranged from 40% to 61% when A. tumefaciens was incubated with leaves from seedlings grown in the dark, whereas leaves from seedlings grown under a 16-h light p hotoperiod showed no GUS, indicating the significant effect of etiolat ion on transient GUS expression mediated by A. tumefaciens.