CHLOROPLAST DNA DIFFERENCES BETWEEN CULTIVATED HOP, HUMULUS-LUPULUS AND THE RELATED SPECIES HEXACENTRUS-JAPONICUS

Chloroplast DNA (cpDNA) of Humulus lupulus and H. japonicus was examin ed by restriction endonuclease analysis with BamHI, BanI, BclI, BstEII , DraI, EcoRI, EcoRV, HindIII, KpnI, PaeR7I, PstI, PvuII, SalI and Xho I. The restriction fragment patterns showed that the cpDNAs shared a l arge number of restriction sites. However, the chloroplast genomes of the two species could be distinguished by differences in restriction s ite and restriction fragment patterns in the PstI, PvuII, BclI, EcoRV, DraI and HindIII digests. On the basis of the complexity of restricti on enzyme patterns, the enzymes PstI, PvuII, SalI, KpnI and XhoI were selected for mapping the chloroplast genomes. Single and double restri ction enzyme digests of cpDNA from the two species were hybridized to cpDNA probes of barley and tobacco. The data obtained from molecular h ybridization experiments were used to construct the cleavage site maps . Except for the PstI digest, the arrangement of cpDNA restriction sit es was found to be the same for both species. An extra PstI site was p resent in H. lupulus. Three small insertions/deletions of about 0.8 kb p each were detected in the chloroplast genomes of the two species. Tw o of these insertions/deletions were present in the large and one in t he small singlecopy region of the chloroplast genome. The cpDNA of Hum ulus was found to be a circular molecule of approximately 148 kbp that contains two inverted repeat regions of 23 kbp each, a small and a la rge single -copy region of approximately 20 kbp and 81 kbp, respective ly. The chloroplast genome of hop has the same physical and structural organization as that found in most angiosperms.