Unstable genes in plants.

The fluidity of the plant genome during development and reproduction has been considered. Although some cases of differential replication have been described there is little evidence for this process playing a large part in development. However the genome flexibility in response to 'shocks' to the genome observed in flax and maize suggest that this process may be important in the generation of rapid changes in genome. These rapid changes appear to occur in particular subsets of the genome which may allow a radical but limited reorganization of the genome in response to genomic challenge.