An Efficient Selection Scheme for Agrobacterium-mediated Co-transformation of Rice Using Two Selectable Marker Genes hpt and bar

Abstract

A stable, efficient, and reliable selection system using bar and hpt as selectable markers for Agrobacterium mediatedco-transformation of rice with two separate vectors was developed. Two plasmids, pMJC-GB-IFS2 and pMJC-GH-CHR carryingbar or hpt gene as selectable markers and isoflavone synthase 2 (IFS2 CHR) gene as target genes,respectively, were used for co-transformation. Between the two selection schemes, either the selection first for hygromycin B resis-tance during the callus proliferation stage and later for phosphinothricine (PT) resistance at the shoot regeneration stage or viceversa, the former selection scheme was far more effective obtaining co-transformed transgenic plants (10%) than the latter(12.8%), meaning that the PPT selection during the callus proliferation stage resulted in producing many escapes without trans-formed bar Agro-bacterium mediated co-transformation of rice.