Evaluation of Leaf Rust Resistance in the Spanish Core Collection of Tetraploid Wheat Landraces and Association with Ecogeographical Variables

Spain has a great landrace diversity of the subspecies of the tetraploid species Triticum turgidum L., namely, durum (or durum wheat), turgidum (or rivet wheat) and dicoccon (or domesticated emmer wheat). These wheats have to confront several foliar diseases such as the leaf rust. In this work, a core collection of 94 landraces of tetraploid wheats were inoculated with three leaf rust isolates. Besides, a larger collection (of 192 accessions) was evaluated in the field. Although the majority of landraces were susceptible, approximately 20% were resistant, especially domesticated emmer wheat landraces. Several variables, such as late heading and red coat seeds were associated to resistant accessions. Regarding ecogeographic variables, a higher rainfall from October to February and more uniform temperature were found in the area of origin of resistant landraces. Based on these results, several resistant landraces were identified that potentially may be used in durum wheat breeding programs. In addition, a predictive model was elaborated to develop smaller subsets for future screening with a higher hit rate for rust resistance.