Abstract
In order to facilitate the isolation of recombinants in brome mosaic virus, a series of duplication mutants with alterations in the RNA3 3' noncoding region has been engineered. The distribution of crossovers, which was observed to be dependent on the parental RNA3 sequence, supported the role of RNA structure in recombination. However, a negative correlation between replication of the parental RNA3 constructs and the accumulation of recombinant progeny confirmed the role of selection.