Regions outside of the leucine-rich repeats of flax rust resistance proteins play a role in specificity determination.

Multiple alleles controlling different gene-for-gene flax rust resistance specificities occur at the L locus of flax. At least three distinct regions can be recognized in the predicted protein products: the Toll/interleukin-1 receptor homology (TIR) region, a nucleotide binding site (NBS) region, and a leucine-rich repeat (LRR) region. Replacement of the TIR-encoding region of the L6 allele with the corresponding regions of L2 or LH by recombination changed the specificity of the allele from L6 to L7.

Analysis of Mutator-induced mutations in the iojap gene of maize.

The recessive nuclear mutation iojap (ij) in maize produces striped plants with normal chloroplasts in green sectors and poorly developed chloroplasts in the white sectors. The ij mutation is also characterized by an array of additional phenotypic affects which suggests a pivotal role for Ij in chloroplast development. The Ij gene from maize has been isolated; however, the sequence has not provided information on the action of the Ij gene product.

Instability of the L6 gene for rust resistance in flax is correlated with the presence of a linked Ac element.

In a programme aimed at tagging rust-resistance genes in flax with the maize transposable element Ac, a primary transformant of a line called 'Forge' that is homozygous for four rust-resistance genes, L6, M, N and P2, was identified that possessed 10 copies of the Ac element, one of which was linked (29 map units) to L6. Descendants of this plant, which had from 8 to 15 copies of Ac, were crossed to a rust-susceptible line and the progeny screened for rust-susceptible mutants. When the Ac linked to L6 was present in the parent, a high frequency of L6 mutants was observed (29 mutants in 30,575).