Detection of new adult plant leaf rust resistance loci in a Tunisian wheat landrace Aus26670

Transfer of leaf resistance genes into elite lines can assist in developing future wheat cultivars and mitigate economic losses caused by the leaf rust pathogen, Puccinia triticina Erikss. (Pt). Some previously reported leaf rust resistance QTL have been challenged by aggressive Pt pathotypes. This experiment aims to detect genetically diverse resistance QTL using a Tunisian landrace, Aus26670, which confers a high level of adult plant leaf rust resistance against Australian Pt pathotypes. One hundred nineteen F₇ recombinant inbred lines (RILs) were generated after crossing Aus26670 and a susceptible line Avocet ‘S’ (AvS). The Aus26670/AvS RIL population was evaluated against mixture of five Pt pathotypes under field conditions for two years. The same RIL population was also screened using three Pt pathotypes individually in the greenhouse under controlled conditions. Genetic analysis of the seedling leaf rust response against Pt104-2,3,6, (7) confirmed the presence of an all-stage resistance (ASR) gene, Lr13. The RIL population was genotyped using a targeted genotyping-by-sequencing (tGBS) assay, and Lr13 was mapped in the 153.9–182.1 Mb region in chromosome 2BS. QTL analysis suggested the involvement of three genomic regions/adult plant resistance genes (APR) namely QLr.sun-1BL/Lr46, QLr.sun-5DL and QLr.sun-7DS, in controlling leaf rust resistance. Data of seedling assays, known marker survey, and comparison of genomic regions detected in this study with previously reported APR indicated the uniqueness of QLr.sun-5DL (559.7 Mb) and QLr.sun-7DS (11 Mb). Both QTL represent new additions to the APR toolbox.