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Soil-borne barley yellow mosaic virus disease--caused by a complex of at least three viruses, i.e. Barley mild mosaic virus (BaMMV), Barley yellow mosaic virus (BaYMV) and BaYMV-2--is one of the most important diseases of winter barley in Europe. The two genes rym4, effective against BaMMV and BaYMV, and rym5, additionally effective against BaYMV-2, comprise a complex locus on chromosome 3HL, which is of special importance to European barley breeding. To provide the genetic basis for positional cloning of the Rym4/Rym5 locus, two high-resolution maps were constructed based on co-dominant flanking markers (MWG838/Y57c10 - MWG010/Bmac29). Mapping at a resolution of about 0.05% rec., rym4 has been located 1.07% recombination distal of marker MWG838 and 1.21% recombination proximal to marker MWG010. Based on a population size of 3,884 F2 plants (0.013% recombination) the interval harbouring rym5 was delimited to 1.49+/-0.14% recombination. By testing segmental recombinant inbred lines (RILs) for reaction to the different viruses at a resolution of 0.05% rec. (rym4) and 0.019% rec. (rym5), no segregation concerning the reaction to the different viruses could be observed. AFLP-based marker saturation for rym4, using 932 PstI+2/MseI+3 primer combinations only resulted in three markers with the closest one linked at 0.9% recombination to the gene. Two of these markers detected epialleles arising from the differential cytosine methylation of PstI sites. Regarding rym5, profiling of 1,200 RAPD primers (about 18,000 loci) and 2,048 EcoRI+3/MseI+3 AFLP primer combinations (about 205,000 loci) resulted in one RAPD marker and seven AFLP markers tightly linked to the resistance gene. Flanking markers with the closest linkage to rym5 (0.05% and 0.88% recombination) were converted into STS markers. These markers provide a starting point for chromosomal walking and may be exploited in marker-assisted selection for virus resistance based on rym5.

Contamination of ergot (Claviceps purpurea) in grains continues to be a problem in outcrossing plants like rye, especially in years of favorable infection (cold, rainy) conditions. The problem is not the yield loss, but the contamination of the grains by toxic alkaloids leading to strict critical values within the European Union. This study was conducted to (1) partition the variation of genotype, inoculation treatments and environment for ergot infection of 12 winter rye genotypes, (2) the effect of varying proportions of a non-adapted restorer gene on ergot, and to (3) reveal within the genotype the relative importance of male pollen fertility and female receptivity on the ergot reaction of single crosses bearing different restorer genes. In total, 12 rye genotypes and two factorial crossing designs with each of five female and four male lines differing in their restorer genes were tested by artificial infection in up to 16 environments in four European countries. High and significant genotypic variation regarding the ergot severity and pollen-fertility restoration were observed. Furthermore significant general combining ability and specific combining ability variances and interactions with environment were obtained. The Electronic supplementary material The online version of this article (

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