Linkage of Lr55 wheat leaf rust resistance gene with microsatellite and DArT-based markers

Every year, leaf rust causes losses of wheat yield and quality all around the world. Breeding of cereals resistant to fungal diseases offers a long-term alternative for chemical protection and becomes increasingly important for organic farming and ecological food production. Accumulation of effective resistance genes in a single genotype requires recurrent enrichment of the wheat genepool with promising resistance alleles marked with DNA tags. Lr55 gene was transferred to KS04WGRC45 wheat from Elymus trachycaulus and provides effective resistance to leaf rust. Two F2 mapping populations Bogatka x KS04WGRC45 (BK) and Nadobna x KS04WGRC45 (NK) were developed in order to identify the molecular marker(s) linked to the Lr55 gene. In total the segregations of 22 microsatellite and 7 DArT-based markers were used to create linkage groups corresponding to 1B chromosomes in individual mapping populations. At consensus map, Lr55 gene was flanked by XGwm374 and XWmc406 markers at distance of 8.3 and 14.8 cM, respectively. Until now, no molecular markers have been reported for Lr55 gene, and the molecular markers developed may be a starting point for the selection of plant materials for the presence of the Lr55 gene. However, additional marker systems based on next-generation sequencing may be necessary for more accurate location of Lr55 gene location.

Automated summary

Breeding resistant cereals to fungal diseases is a long-term alternative to chemical protection against leaf rust, with the Lr55 gene providing effective resistance. Developing molecular markers linked to the Lr55 gene through F2 mapping populations is essential for identifying resistance alleles in wheat genepools.