RAPD polymorphisms detected among the flax genotrophs

The occurrence of environmentally induced heritable changes in certain flax varieties has been shown to be accompanied by changes in the genomic DNA. A large difference in nuclear DNA contents has been characterized between t he extreme types, termed genotrophs. The genomic variation between a series of genotrophs has been studied by the polymerase chain reaction using rand om arbitrary oligonucleotide primers. A total of 320 primers were used in t he reactions and 253 polymorphic bands observed. The polymorphic bands were derived from all parts of the genome, namely the highly repetitive, middle -repetitive and low-copy-number sequences. They were also shown to be distr ibuted thoughout the genome. In one group of genotrophs, all of which were induced by temperature treatment, there was a clustering of the polymorphis ms with a high degree of shared polymorphisms. These results are in agreeme nt with earlier studies showing that a dispersed fraction of the genome is susceptible to variation when environmentally induced heritable changes occ ur.