A detailed restriction endonuclease site map of theZea mays plastid genome

Fragments produced by partial digestion of plastid DNA fromZea mays withEco RI were cloned in Charon 4A. A circular, fine structure physical map of the plastid DNA was then constructed from restriction endonucleaseSal I,Pst I,Eco RI, andBam HI recognition site maps of cloned overlapping segments of the plastid genome. These fragments were assigned molecular weights by reference to size markers from both pBR322 and lambda phage DNA. Because of the detail and extent of the derived map, it has been possible to construct a coordinate system which has a unique zero point and within which all the restriction fragments and previously described structural features can be mapped. A computer program was constructed which will display in a circular fashion any of the above features using an X-Y plotter.