Genetic mapping of the Cre8 locus for resistance against cereal cyst nematode (Heterodera avenae Woll.) in wheat

The cereal cyst nematode (CCN, Heterodera avenae Woll.) resistance locus Cre8 on the long arm of chromosome 6B (6BL) of wheat (Triticum aestivum L.) is effective in lowering the nematode population in soil. Identification of reliable and high-throughput molecular markers linked to the Cre8 locus is important for the successful deployment of Cre8-derived resistance in wheat breeding programs. Here, we report the addition of over 600 markers to improve an existing linkage map for the Trident/Molineux wheat population. With the improved map, Cre8 was mapped as a large-effect quantitative trait locus (QTL) near the distal end of 6BL. This QTL explained up to 35 % of the phenotypic variation in CCN resistance. New marker assays were developed for DNA polymorphisms in the Cre8 region. Seven molecular markers closely linked with Cre8 (at 0.9, 2.2 or 5.9 cM from the estimated QTL position) were found to be diagnostic across a panel of wheat cultivars and are recommended for use in marker-assisted selection of the Cre8 resistance locus in wheat breeding. Prospects for the isolation of the causal gene are discussed.