Development of candidate introgression lines using an exotic barley accession (Hordeum vulgare ssp spontaneum) as donor

In the present paper, we report on the selection of two sets of candidate introgression lines (pre-ILs) in spring barley. Two BC2DH populations, S42 and T42, were generated by introgressing an accession of Hordeum vulgare ssp. spontaneum (ISR42-8, from Israel) into two different spring barley cultivars, Scarlett (S) and Thuringia (T). From these BC2DH populations two sets with 49 (S42) and 43 (T42) pre-ILs were selected, and their genomic architecture as revealed by SSR marker analysis was characterised. The selected pre-ILs cover at least 98.1% (S42) and 93.0% (T42) of the exotic genome in overlapping introgressions and contain on average 2 (S42) and 1.5 (T42) additional non-target introgressions. In order to illustrate a potential application and validation of these pre-ILs, the phenotypic effect of the exotic introgression at the locus of the major photoperiod response gene Ppd-H1 was analysed. Pre-ILs carrying the introgression at the Ppd-H1 locus flowered significantly earlier than the elite parents, and the introgression maintained its effect across the two genetic backgrounds and across four tested environments. The selected pre-ILs represent a first promising step towards the assessment and utilization of genetic variation present in exotic barley. They may promote the breeding progress, serve for the verification of QTL effects and provide a valuable resource for the unravelling of gene function, e.g. by expression profiling or map-based cloning.