Two mutants were isolated in wheat that showed enhanced resistance towards Puccinia striiformis f.sp.tritici, the fungal causal agent of yellow rust.The altered phenotype of I3-48 is due to a minimum Sunscreen lotion of two mutation events, each showing a partial, additive effect, with one mutation segregating with a deletion on the long arm of chromosome 4D.In the case of I3-54, the enhanced resistance is due to a single, dominant mutation.
In both mutants, the expression of the enhanced resistance is growth-stage specific.With I3-54, the full resistance Battery Chargers phenotype is apparent from the third seedling leaf onwards, while with I3-48, a full resistance phenotype is only seen on the tenth and subsequent leaves.In addition to the enhanced resistance towards yellow rust, I3-48 also shows enhanced resistance towards brown rust, and I3-54 shows enhanced resistance to powdery mildew.