The action of the gene Sr6 for stem rust resistance in wheat is affected by temperature, light, and the particular susceptible parent with which a line carrying Sr6 has been crossed. Two experiments were carried out to deter-mine whether the effect of the susceptible parents was due to modifier genes, the general genetic background, or interallelic interactions. The data indicated that the susceptible parents carried different sr6 alleles that interacted with Sr6, possibly in a paramutation-like process. In the course of the study, a number of anomalous results were obtained that may be due to the action of transposable elements.
Theoretical and Applied Genetics