AB-QTL analysis in winter wheat: II. Genetic analysis of seedling and field resistance against leaf rust in a wheat advanced backcross population

Abstract

The present study aimed to localize exotic quantitative trait locus (QTL) alleles for the improvement of leaf rust (P. triticina) resistance in an advanced backcross (AB) population, B22, which is derived from a cross between the winter wheat cultivar Batis (Triticum aestivum) and the synthetic wheat accession Syn022L. The latter was developed from hybridization of T. turgidum ssp. dicoccoides and T. tauschii. Altogether, 250 BC 2 F 3 lines of B22 were assessed for seedling resistance against the leaf rust isolate 77WxR under controlled conditions. In addition, field resistance against leaf rust was evaluated by assessing symptom severity under natural infestation across multiple environments. Simultaneously, population B22 was genotyped with a total of 97 SSR markers, distributed over the wheat A, B and D genomes. The phenotype and genotype data were subjected to QTL analysis by applying a 3-factorial mixed model analysis of variance including the marker genotype as a fixed effect and the environments, the lines and the marker by environment interactions as random effects. The QTL analysis revealed six putative QTLs for seedling resistance and seven for field resistance. For seedling resistance, the effects of exotic QTL alleles improved resistance at all detected loci. The maximum decrease of disease symptoms (-46.3%) was associated with marker locus Xbarc149 on chromosome 1D. For field resistance, two loci had stable main effects across environments and five loci exhibited marker by environment interaction effects. The strongest effects were detected at marker locus Xbarc149 on chromosome 1D, at which the exotic allele decreased seedling symptoms by 46.3% and field symptoms by 43.6%, respectively. Some of the detected QTLs co-localized with known resistance genes, while others appear to be as novel resistance loci. Our findings indicate, that the exotic wheat accession Syn022L may be useful for the improvement of leaf rust resistance in cultivated wheat.

Genetic analysis and detection of new QTL alleles for Septoria tritici blotch resistance using two advanced backcross wheat populations

“…This SNP data together with simple sequence repeats (SSRs) markers as described in Naz et al. () were collectively used to perform QTL analysis in this study.…”

Domestication and crop evolution of wheat and barley: Genes, genomics, and future directions

“…Some groups have created AB‐NAM barley populations including the Halle Exotic Barley 25 (HEB‐25; Maurer et al ) and another created using accessions from the Wild Barley Diversity Collection (WBDC; Steffenson et al ; Nice et al ). Additional AB‐QTL studies have also been conducted in wheat (Kunert et al ; Naz et al ; Naz et al ).…”

Impact of Genomic Technologies on Chickpea Breeding Strategies

“…This approach results in simultaneous discovery of QTL and development of introgression lines requiring only a few additional generations to develop NILs and varietal development [13]. The AB-QTL approach has been extensively used in vegetable and field crops species, like tomato [119], rice [120], wheat [121], common bean [122] and soybean [105,123]. In the case of chickpea, some efforts have also been initiated at ICRISAT to undertake AB-QTL analysis.…”