Abstract
Barley yellow mosaic virus disease caused by different strains of BaYMV
and BaMMV is a major threat to winter barley cultivation in Europe.
Different resistance genes against these viruses have been mapped and
suitable PCR-based markers have been developed. In this respect doubled
haploid (DH) populations proved to be advantageous as they facilitate a
repeated test for resistance against all agents of the barley yellow
mosaic virus complex and besides this, dominant marker systems are as
informative as co-dominant ones in DHs due to the lack of heterozygous
genotypes. Using DH populations resistance genes rym4, rym5, rym11,
rym13, rym15 and the BaYMV/BaYMV-2 resistance of the barley cultivar
�Chikurin Ibaraki 1� have been mapped. DHs are also well suited to
pyramiding resistance genes against BaMMV and BaYMV. Since homozygous
recessive genotypes are more frequent in DHs than in segregating F-2
populations, DHs can be efficiently used to create broad-spectrum
resistance and to extend the usability of partly overcome resistance
genes. Results from employing two different strategies for pyramiding,
based on one and two DH-steps, respectively, combining three recessive
resistance genes, i.e. rym4/rym5, rym9 and rym11, are presented. The
faster strategy based on one haploidy step resulted in the
identification of all three and two-way combinations of the respective
resistance genes.
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