Validation of quantitative trait loci for multiple disease resistance in barley using advanced backcross lines developed with a wild barley

Quantitative trait loci (QTLs) for resistance to spot blotch {Cochliobolus sativus (Ito & Kurib.) Drechs. ex Dastur [anamorph: Bipolaris sorokiniana (Sacc. in Sorok.) Shoem.]}, net type net blotch (NTNB, Pyrenophora teres f. teres), Septoria speckled leaf blotch (SSLB, primarily Septoria passerinii Sacc.), and leaf scald [caused by Rhynchosporium secalis (Oudem.) Davis] were previously detected in a recombinant inbred line (RIL) population derived from a cross between the wild barley [Hordeum vulgare subsp. spontaneum (K. Koch) Thell.] accession OUH602 and the two-rowed malting barley (H. vulgare L.) cultivar Harrington. Our objectives in this study were to develop and genetically characterize an advanced backcross (AB) population with OUH602 as the donor parent and Harrington as the recurrent parent, to validate seedling disease resistance QTLs detected in the OUH602/Harrington RIL population, and to identify adult plant spot blotch resistance QTLs. We developed an AB population (BC₂F_6:8) and genotyped the population with a set of 111 simple sequence repeat (SSR) markers. The estimated donor-parent genome introgression averaged 11.25%. A QTL analysis of the AB population validated all major QTLs previously identified in the OUH602/Harrington RIL population. No new QTLs for seedling resistance were identified in the AB population, indicating that AB populations do not provide an advantage compared with RIL populations for detecting seedling disease resistance QTLs. A previously unidentified QTL conferring adult plant spot blotch resistance was identified on chromosome 4(4H). The resistance alleles for each of the QTLs were contributed by OUH602. The AB population is a valuable resource for further genetic studies and breeding applications.