This invention provides compositions and methods for the transformation of
plastids of plant cells with multiple genes, and proper association or
assembly of multimeric proteins that are heterologous to the plastids of
plant cells. A plasmid construct encoding all of the individual
polypeptide components of the multimeric protein is provided. Stable
integration of the heterologous coding sequences into the plastid genome
of the target plant is accomplished through homologous recombination. The
present invention achieves assembly of immunoglobulin heavy and light
chains, with covalent bonding between the chains, into immunologically
active immunoglobulins in the chloroplast.