Genotypic variation of Agrobacterium-mediated transformation of Italian ryegrass
Gi Jun Choi
Sei Hyung Yoon
Hee Chung JI
Hyung Soo Park
Young Chul Lim
Financial support: This work was supported by grants from the National Institute of Animal Science (Project no. 200901OFT082558123) and the BioGreen 21 Program (Project no. 20070301-034-015), Rural Development Administration (RDA), Korea.
Keywords: Agrobacterium, forage crop, Italian ryegrass, transgenic plants.
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.