A method of transforming plant plastids and regenerating fertile
transplastomic plants by somatic embryogenesis is disclosed. The method
involves transforming a plant plastid in a plant cell capable of being
regenerated through somatic embryogenesis with a plastid expression
cassette comprising one or more selectable marker genes that express in
both green and non-green tissue and in light and dark conditions wherein
the selectable marker plant cell is cultured in the presence of the plant
cell to a selection agent. The transplastomic plant cell is cultured in
the presence of the selection agent under conditions to cause the
formation of a somatic embryo. The somatic embryo is grown into a fertile
transplastomic plant. Preferably, the expression cassette contains two
different selectable marker genes that express different proteins that
provide plant cell resistance to the same selection agent.