GENETIC ANALYSES OF MALE-FERTILITY RESTORATION IN WHEAT .3. EFFECTS OF ANEUPLOIDY

Effects of aneuploidy and modifier genes on the expression of male-fertility restoring (Rf) genes were studied in five sets of F1 monosomics from crosses involving male-sterile 'Chris' monosomics and five R-lines of wheat, Triticum aestivum L. Two lines were Rf1Rf1, two were Rf4Rf4, and one (the progenitor of the other four lines) was Rf1Rf1 Rf4Rf4 and had other unidentified Rf genes. Rf1 and Rf4 are located on Chromosomes 1A and 6B, respectively. The fertility of the F1 monosomics within and between the five sets of crosses indicated that one Rf1Rf1 and one Rf4Rf4 line had additional recessive male-fertility restoring genes. Also, the fertility was significantly enhanced in some of the F1 monosomics of homoeologous Groups 1 and 7, greatly reduced in the F1 monosomics of Groups 3 and 6, and substantially reduced in five other monosomics: 2A, 2B, 4B, 5B, and 5D. Thus, male fertility in this material is evidently conditioned by interactions among genes located on at least 17 chromosomes of wheat. The enhanced fertility of the F1 monosomics of homoeologous Groups 1 and 7 is attributed to the action of homoeoalleles in those groups which function better in five doses than in the normal six.