An efficient selection scheme for Agrobacterium-mediated co-transformation of rice using two selectable marker genes hpt and bar.

摘要

A stable, efficient and reliable selection system using bar and hpt as selectable markers for an Agrobacterium-mediated co-transformation of rice with 2 separate vectors was developed. Two plasmids, pMJC-GB-IFS2 and pMJC-GH-CHR, carrying bar or hpt genes as selectable markers. and isoflavone synthase 2 (IFS2) or chalcone reductase (CHR) genes as target genes, respectively, were used for co-transformation. Between the 2 selection schemes, either the selection for hygromycin B resistance during the callus proliferation stage and later for phosphinothricine (PPT) resistance at the shoot regeneration stage or vice versa, the former selection scheme was far more effective obtaining co-transformed transgenic plants (100%) than the latter (12.8%), meaning that the PPT selection during the callus proliferation stage resulted in producing many escapes without the transformed bar gene. It was suggested that the hygromycin B selection must precede the PPT selection for efficient Agrobacterium-mediated co-transformation of rice..