PHYSICAL MAP OF CHLOROPLAST DNA IN SUGI, CRYPTOMERIA-JAPONICA

To investigate the evolution of conifer species, we constructed a phys ical map of the chloroplast DNA of sugi, Cryptomeria japonica, with fo ur restriction endonucleases, PstI, SalI, SacI and XhoI. The chloropla st genome of C. japonica was found to be a circular molecule with a to tal size of approximately 133 kb. This molecule lacked an inverted rep eat. Twenty genes were localized on the physical map of C. japonica cp DNA by Southern hybridization. The chloroplast genome structure of C. japonica showed considerable rearrangements of the standard genome typ e found in vascular plants and differed markedly from that of tobacco. The difference was explicable by one deletion and five inversions. Th e chloroplast genome of C. japonica differed too from that of the genu s Pinus which also lacks one of the inverted repeats. The results indi cate that the conifer group originated monophyletically from an ancien t lineage, and diverged independently after loss of an inverted repeat structure.