LAUSR

Ascochyta blight is one of the most damaging pea diseases. Resistance to this disease in pea is quantitative, being governed by several genes with minor effect. Knowledge of the genes controlling resistance would allow their pyramiding and tracking in breeding programs. In previous studies, a number of QTLs associated with resistance to this disease have been identified. Complementarily, genes differentially expressed in resistant reactions have been identified. However, the actual genes controlling resistance, underlying these QTLs are unknown. Previously, genes with a putative involvement in defense and located into QTLs associated with resistance to P. pinodes, have been postulated as candidate genes. This study wanted to go a step forward, being the first report of candidate genes involved in defense that, besides being located in a genomic region controlling resistance, are also differentially expressed in resistant reactions. With this aim, in this study ten genes previously shown to be induced after infection in the resistant accession P665 were selected and mapped in the RIL population P665 × Messire, previously used to identify QTLs for resistance to this disease. In addition, another gene, that according to other pea maps, could be located into a QTL associated with resistance in this RIL population, was also mapped. Single-marker analysis revealed that five candidate genes showed a significant correlation with resistance traits, being also located in a genomic region showing an increased LOD for the corresponding trait. Furthermore, two of them were in the 2-LOD interval of QTLs associated with resistance traits.