In the present study, genotypic variation of Agrobacterium-mediated
transformation of Korean Italian ryegrass has been evaluated. Mature
seed-derived calli of seven cultivars were inoculated and co-cultured
with Agrobacterium tumefaciens carrying the binary vector pCAMBIA1301,
which contains a reporter gene (gus) and a plant selectable marker gene
conferring resistance to hygromycin (hpt) in the T-DNA region. The
effects of several factors such as callus type and callus age on
transformation effectiveness and the expression of the GUS gene were
investigated. The highest transformation effectiveness (6.7%) was
obtained with the Hwasan 101 cultivar when 9-week-old calli (type-I)
were inoculated with Agrobacterium. The overall transformation rates of
the examined cultivars ranged from 0.4% to 6.7%. GUS histochemical
assays, PCR, and southern analysis of transgenic plants demonstrated
that transgenes were successfully integrated into the genome of Italian
ryegrass. Thus, evaluation of transformation effectiveness and
selection of a suitable cultivar of Italian ryegrass may improve
molecular breeding of this species