The first requirement for transplastomic plant generation is to have a suitable gene construct that can be introduced into a plastid like a chloroplast in the form of an E. coli plasmid vector.[8] There are several key features of a suitable gene cassette including but not limited to (1) selectable marker (2) flanking sequences (3) gene of interest (4) promoter sequences (5) 5' UTR (6) 3' UTR (7) intercistronic elements.[9] The selectable marker typically tends to be an antibiotic resistant gene, which would give the plant cell the ability to tolerate being grown on antibiotic containing agar plates.[3] Flanking sequences are crucial for introduction of the gene construct at precise predetermined points of the plastid genome through homologous recombination.[4] The gene of interests introduced have many different applications and can range from pest resistance genes to vaccine antigen production.[4] Intercistronic elements (IEE) are important for facilitating high levels of gene expression if multiple genes are introduced in the form of an operon.[4] Finally, the 5' UTR and 3' UTR enhances ribosomal binding and increases transcript stability respectively.[4]