Structural Analysis of a Genomic Region for the Leaf Rust Resistance Gene, LrRW12, on Wheat Chromosome 6B

Leaf rust is one of the most important diseases for the wheat production through the world. To date, a large number of resistance genes against the leaf rust (Lr genes) have been identified, most of which were known to derive from wild relatives of wheat. Previous studies revealed that a single resistance gene in a common wheat accession of “RW-12”, designated as LrRW12, was introduced from a wild emmer wheat and is located on chromosome 6B. The aim of our current study is to identify the genomic region of LrRW12 and to find the sequences for the possible candidates of LrRW12. The LrRW12 was genetically mapped on the long arm of chromosome 6B (6BL) by the GBS approach using F₂ population that was derived from the cross between a resistant accession of “Sabikei 14” carrying LrRW12 and a susceptible accession of “Miyagino-komugi”. The SNP markers were developed along the genome assemblies of chromosome 6B, and finally about 4 Mb region on the distal end of 6BL were identified to include LrRW12. From the assemblies for this region, 236 genic loci were predicted by the gene annotation program MEGANTE (Numa and Itoh 2014) and transcriptome data set from “RW-12” and “Miyagino-komugi”. Comparison of the transcript sequences between both accessions detected 82 SNPs on 21 loci, which included two loci with non-synonymous polymorphism. This work was supported by grants from the Ministry of Agriculture, Forestry and Fisheries of Japan (NGB1003) and JSPS KAKENHI Grant Number JP24780008.