Comparative AB-QTL analysis in barley using a single exotic donor of Hordeum vulgare ssp. spontaneum

This paper reports on the first comparative advanced backcross quantitative trait locus (AB-QTL) study in barley. The BC(2)F(2) population Hx101 was generated from crossing var. Harry [H; Hordeum vulgare ssp. vulgare ( Hv)] with ISR101-23 [101; H. v. ssp. spontaneum ( Hsp)]. The results of the AB-QTL analysis for 13 quantitative traits are presented and, subsequently, compared with the AB-QTL study of the barley cross Apex x ISR101-23 (Ax101; Pillen et al., Theor Appl Genet 107:340-352). Both AB populations share the exotic Hsp donor accession ISR101-23. In Hx101, 108 putative QTLs (17%) were identified among the 650 markerxtrait combinations tested. Altogether 52 (48 %) favorable effects were identified from the exotic parent. At these marker loci, the homozygous Hsp genotype was associated with an improvement in the trait compared to the homozygous Hv genotype. The percentage of QTLs detected in Hx101 was comparable to that in Ax101 (17% vs. 15%), however more favorable exotic QTL alleles were located in Hx101 than in Ax101 (48% vs. 34%). In Hx101, the Hsp QTL allele at EBmac0679([4H]) was associated with a yield increase of 5.9% averaged across the six environments tested. A comparison of putative QTLs between Hx101 and Ax101 was based on 26 shared SSR markers. In total, 26% of the putative QTLs could be detected simultaneously in both AB populations. This finding indicates that only a portion of the QTL effects of the donor allele can be transferred from one elite recipient to the next.