Efficient plastid transformation in tobacco using the aphA-6 gene and kanamycin selection.

Here we report on the development of a new dominant selection marker for plastid transformation in higher plants using the aminoglycoside phosphotransferase gene aphA-6 from Acinetobacter baumannii. Vectors containing chimeric aphA-6 gene constructs were introduced into the tobacco chloroplast using particle bombardment of alginate-embedded protoplast-derived micro colonies or polyethylene glycol (PEG)-mediated DNA uptake. Targeted insertion into the plastome was achieved via homologous recombination, and plastid transformants were recovered on the basis of their resistance to kanamycin. Variations in kanamycin resistance in transplastomic lines were observed depending on the 5' and 3' regulatory elements associated with the aphA-6 coding region. Transplastomic plants were fertile and showed maternal inheritance of the transplastome in the progeny.