Allelic and Haplotypic Diversity at the Rp1 Rust Resistance Locus of MaizeSequence data from this article have been deposited with the EMBL/GenBank Data Libraries under accession nos. AY309779, AY309780, AY309781, AY309782, AY309783sc and scAY581258sc.

Abstract

The maize Rp1 rust resistance locus is a complex consisting of a family of closely related resistance genes. The number of Rp1 paralogs in different maize lines (haplotypes) varied from a single gene in some stocks of the inbred A188 to >50 genes in haplotypes carrying the Rp1-A and Rp1-H specificities. The sequences of paralogs in unrelated haplotypes differ, indicating that the genetic diversity of Rp1-related genes is extremely broad in maize. Two unrelated haplotypes with five or nine paralogs had identical resistance phenotypes (Rp1-D) encoded in genes that differed by three nucleotides resulting in a single amino acid substitution. Genes in some haplotypes are more similar to each other than to any of the genes in other haplotypes indicating that they are evolving in a concerted fashion.