FIGURE 1.

Schematic outline of the mapping population design. The tetraploid Hb accession A42, resistant to the isolate CH4.8, was crossed to the tetraploid derivative of the susceptible barley cultivar “Borwina.” From tetraploid F1 hybrids, two different introgression mapping populations were developed: the “4176” population was developed by backcrossing the F1 hybrid once to the parent “Borwina,” followed by five generations of selfing. A gray arrow indicates a selfing generation. The “5216” population was derived from six generations of selfing from the F1 hybrid. In the course of development of populations “4176” and “5216,” the generations were diploid from BC1F2 and F2, respectively. Through the population development, each new selfing generation was obtained by selecting and selfing a single resistant heterozygous plant identified by resistance test with the powdery mildew isolate CH4.8 and marker data analysis, in order to promote recombination.