RETRACTED: Production of transgenic orchardgrass via Agrobacterium-mediated transformation of seed-derived callus tissues

An Agrobacterium-mediated genetic transformation method for orchardgrass (Dactylis glomerata L.) has been developed from seed-derived callus. In order to optimize the conditions for orchardgrass transformation, several factors known to influence Agrobacterium-mediated DNA transfer were examined. Seed-derived embryogenic calli were co-cultivated with A. tumefaciens strains harboring the binary vector pIG121Hm. Transient GUS expression was greatly affected by the A. tumefaciens strain, the duration of co-cultivation, and the presence of acetosyringone during inoculation and co-cultivation. Among the three strains tested, EHA101 was most effective for transient GUS expression, followed by GV3101 and LBA4404. The inclusion of 200 mM acetosyringone in both the inoculation and co-cultivation media increased transient GUS expression from 16.1 to 56.1% in targeted callus tissues. The transgenic nature of primary transformants was demonstrated by GUS activity. Integration of T-DNA into the genome of putative transgenic plants was confirmed by PCR and Southern blot analyses. One or two copies of the transgene were observed in all transgenic plants analyzed. The transgenic plants had a morphologically normal phenotype and the overall transformation efficiency was 4.8%. Thus, Agrobacterium-mediated genetic transformation can be used for the generation of transgenic orchardgrass containing genes of agronomic importance. # 2006 Elsevier Ireland Ltd. All rights reserved.