Chromosomal location of genetic male sterility genes in four mutants of hexaploid wheat

Few genetic male sterility (GMS) genes have been mapped in hexaploid wheat (Triticum aestivum L.). Our objective was to locate to chromosomes the GMS genes in mutants FS2, FS3, FS20, and FS24. We crossed each mutant to the Cornerstone male sterile, which has the ms1c allele, to determine allelic relationships. We crossed the FS20 mutant to 'Chris' monosomics, and observed segregation in the F-2 and backcrosses to FS20. After observing the results, we made appropriate crosses to Chinese Spring (CS) ditelosomic lines to locate and map the genes to chromosome arms. The allelism test to Cornerstone indicated that the mutants FS2, FS3, and FS24 were allelic to ms1. In the monosomic analysis of the mutated FS20 gene, half of the monosomic 3A plants were male sterile. Therefore, the mutated gene in FS20 was located in chromosome 3A. This conclusion was confirmed by analyzing segregation ratios in backcross populations involving chromosome 3A. The FS20 mutant was crossed with CS ditelosomic 3AS and 3AL, and the monotelodisomic 3AS plants were male sterile. Therefore, the FS20 gene was in chromosome arm 3AL. A backcross of monotelodisomic 3AL plants to FS20 was used to map the mutated gene in FS20 relative to the centromere. The linkage chi-square test indicated that the FS20 gene was not linked to the centromere of chromosome 3A. The gene symbol ms5 was assigned to the mutated gene in FS20, and gene symbols ms1d, ms1e, and ms1f were assigned to the mutations in FS2, FS3, and FS24, respectively.