| The F3 recombinant mapping population utilized in this study was developed within our research group (Mahadevappa et al. 1994, GNM-37-460). The recombinant lines selected were derived from reciprocal crosses among nearly-isogenic barley lines developed for reaction to E. graminis f. sp. hordei (causal agent of powdery mildew). Initial crosses were constructed between the Franger and Rupee accessions containing the Mla6 and Mla13 alleles, respectively . The mapping population was selected by analyzing endosperm extracts from 1800 F2 seeds for recombinant C and B hordein polypeptide patterns. These recombinant patterns indicate genetic recombination between the Hor1 and Hor2 loci, which flank the Mla region. Embryo halves from the selected F2 heterozygous recombinants were planted in the greenhouse to generate recombinant F3 families. The recombinant F3 families were screened to identify homozygous lines, via analysis of the C and B hordein proteins. These F3 homozygous recombinant lines were planted and leaf tissue was harvested for DNA extraction. F4 seeds were collected and analyzed to confirm that these recombinant lines were homozygous. The Mla6 allele was mapped by inoculating F4 progeny with the Erysiphe graminis isolates 5874. Mla13 and Mla14 were mapped using isolate A27. |
