Genetic mapping of pollen fertility restoration QTLs in rye (Secale cereale L.) with CMS Pampa

Cytoplasmic male sterility (CMS) is a widely applied plant breeding tool for hybrid seed production. The phenomenon is often caused by chimeric genes with altered open reading frames (ORFs) located in the mitochondrial genomes and expressed as novel genotoxic products that induce pollen abortion. The fertility of CMS plants can be restored by nuclear-encoded genes that inhibit the action of ORFs responsible for pollen sterility. A recombinant inbred line (RIL) mapping population S64/04/01, encompassing 175 individuals, was used for genetic map construction and identification of quantitative trait loci (QTLs) responsible for fertility restoration in rye (Secale cereale L.) with CMS Pampa. The genetic map of all seven rye chromosomes included 15,516 SNP and silicoDArT markers and covered 1070.5 cm. Individual QTLs explaining 60% and 5.5% of the fertility trait’s phenotypic variance were mapped to chromosomes 4R (QRft-4R) and 5R (QRft-5R), respectively. Association mapping identified markers with the highest R2 value of 0.58 (p value = 2.21E-28). Markers showing the highest associations with the trait were also mapped to the 4R chromosome within the QRft-4R region. Based on marker sequence homology, putative genes involved in pollen fertility restoration were suggested. Five silicoDArTs were converted into PCR-based markers for further breeding purposes.