Quantitative trait loci for root lesion nematode (Pratylenchus thornei) resistance in Middle-Eastern landraces and their potential for introgression into Australian bread wheat

Abstract

Plant parasitic nematodes are a major biotic cause of wheat yield loss in temperate wheat-growing regions. Previous studies using Australian germplasm and/or synthetic hexaploid lines have identified quantitative trait loci (QTLs) for root lesion nematode resistance on chromosomes 2B, 6D, and 7A. This study examines Pratylenchus thornei resistance in 2 Middle-Eastern landraces (AUS13124 and AUS4926), using doubled haploid populations generated by crossing with the susceptible Australian cultivar Janz. Single marker regression and QTL analysis identified resistance loci on chromosomes 2B, 3B, 6D, and 7A, and a susceptibility locus on chromosome 1B. The 2B and 6D loci, which have been reported to explain up to 19% and 24% of variation, respectively, in previous studies, made smaller contributions in the Middle-Eastern varieties, explaining 2–13% (2B) and 1–6% (6D) of phenotypic variation in these populations. The previously reported 7A locus (P. neglectus resistance) was detected through single marker regression only (AUS13124 × Janz – LRS = 4.1, P = 0.04292; AUS4926 × Janz – LRS = 9.6, P = 0.00195), with genotype at the microsatellite marker Xgwm350.3 accounting for 3–23% of phenotypic variation. The previously unreported resistance QTL, located on chromosome 3B, explained up to 24% of phenotypic variation, and the susceptibility locus on chromosome 1B explained up to 21%. The 3B locus was detected in both the AUS13124 × Janz (max. LRS = 20.13) and AUS4926 × Janz (max. LRS = 11.19) populations, and the 1B locus was detected in the AUS4926 × Janz population (max. LRS = 18.82) only.