J Appl Genetics (2011) 52:313–318 on genetic maps can be expanded by multiple rounds of meiosis during inbreeding (Teuscher et al. 2005). The RILs population 541×Ot1-3 is more advanced than 541×2020LM as concerns the inbreeding (F9 vs. F5), but this fact only partly explains significant differences in recombination frequency. Average frequency of recombinants per meiosis stays with agreement with the distances between Rfc1 locus and molecular markers on the integrated genetic map (Table 3). Five DArT markers segregating in both mapping populations are located on this map about 2.5 cM from the Rfc1 gene, but differences between recombination frequen- cies in both studied populations are appreciable in high values of standard deviation. As suggested by Palmer et al. (1998), factors affecting the recombination efficiency, like genotype × environment interactions, possible differences in chromosome structure between parents and genetic background of mapping populations may partially explain observed inconsistencies. Expressing of more general conclusions regarding the precise localization of the Rfc1 gene is currently rather difficult. This is caused by a relatively low number of genotyped lines within mapping populations and by possible inaccuracy in genetic maps as a result of heterogeneity of some RILs not detectable when dominant molecular markers are used for genotyping. Warzecha and Salak-Warzecha (1996) suggest that sources of sterility- inducing cytoplasms CMS-C and CMS-G are genetically very similar or even identical. Localization of the Rfc1 locus on the long arm of the 4R chromosome stays with agreement with observations done by Börner et al. (1998) about position of the Rfg1 gene controlling restoration of male fertility in rye with G cytoplasm. In the same region of rye genome, the gene controlling pollen production of rye with Pampa cytoplasm was mapped by Miedaner et al. (2000). Unfortunately, the lack of common molecular markers (with the only exception of Xpsr119) and insuffi- cient density of genetic maps reported before (Börner et al. 1998; Miedaner et al. 2000) do not allow for concluding about identity of nuclear genes regulating release of pollen by plants with different sources of CMS. It can be stated however, that the 4RL chromosome is a region of rye genome with a great importance as regards of restoration of male fertility in different CMS systems. It should be stressed, that as a result of this study a group of DArT markers tightly linked to the Rfc1 gene was identified. These markers may be useful as a tool for further genetic analyses of CMS-C system, especially if positional cloning of the Rfc1 gene were performed with the use of genomic libraries of rye. Low frequency of recombination between Rfc1 and indicated markers also opens new perspectives for effective marker-assisted selection in the development of rye hybrids based on the CMS-C system. Obviously, hybridization of selected genotypes with whole 317 rye DArT chip is economically not recommendable but sequencing DNA of clones tightly linked with the Rfc1 gene should allow for development of polymorphic PCR- SCAR markers applicable in commercial breeding. Acknowledgements This research was financially supported by the Polish Ministry of Education and Science (project NN 302 361833) and by the Polish Ministry of Agriculture and Rural Development. 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