In vitro regeneration and transformation studies were conducted on two cult
ivars of gladiolus. Cormels of 1.0 to 1.5 cm diameter cut into 2-3 mm thick
slices of top, middle and bottom, and in vitro derived bisected shoot tips
were used as explants on MS medium supplemented with 18.6 mu M kinetin for
multiple shoot induction. Amongst the cormel slices, the top slice gave be
tter shoot induction response of 89% with an average of 2.4 shoots per expl
ant over both cultivars. In vitro derived bisected shoot tips were inoculat
ed on the medium oriented cut-side up, cut-side down and vertically both wi
th and without the cormel base attached. Bisected shoot tips without attach
ed cormel base and inoculated in the cut-side down orientation showed an av
erage of 90% shooting response. In vitro derived shoot tips were used as ex
plants for transformation. Explants were wounded by scalpel and particle bo
mbardment with 1.6 mu m naked gold particles by the biolistic delivery syst
em. The wounded explants, after 3 d of recovery period, were cocultivated w
ith Agrobacterium strain LBA4404 harbouring the binary vectors pBI141 and p
TOK233 which contained gus reporter gene with rice actin and 35S promoters
respectively. GUS expression frequencies of 5.3% and 23% was obtained from
scalpel and particle bombardment wounded explants, respectively. Particle w
ounded explants showed an average of 63 and 103 GUS spots when co-cultivate
d with pBI141 and pTOK233 binary vectors respectively. Explants co-cultivat
ed with pBI141, after three weeks of selection on antibiotic containing med
ium showed blue streaks of GUS expression. It was concluded that Agrobacter
ium could infect the monocot gladiolus and transform the tissue efficiently
when tissues were prewounded with naked gold particles delivered by partic
le gun.