PHYSICAL MAPPING OF THE 5S RIBOSOMAL-RNA MULTIGENE FAMILY IN COMMON WHEAT

In situ hybridization in conjunction with deletion mapping was used to physically map the 5S rRNA multigene family in Triticum aestivum L. cv. 'Chinese Spring.' Twelve 5S rRNA loci were mapped on chromosomes of homoeologous group 1 (arms 1AS, 1 BS, and 1DS) and group 5 (arms 5AS, 5BS, and 5DS). The 5S rRNA loci were mapped (fraction of the distance from the centromere) at positions 0.77, 0.96, 0.76, 0.63, and 0.64 on arms 1AS, 1DS, 5AS, 5BS, and 5DS, respectively. The 5S rRNA locus on 1BS was mapped at position ca. 0.5 of the satellite length. Deletions were used to further map the 5S rRNA loci to chromosome bands 1AS12, 1BS32, 1DS22, 5AS22, 5BS22, and 5DS22. The 5S rRNA loci were not associated with major C-bands on arms 1BS, 1DS, and 5BS. The mapped 5S rRNA loci on the chromosomes of homoeologous group 1 are designated 5S-Rrna-A1, 5S-Rrna-B1, and 5S-Rrna-D1, and the homoeologous group 5 set are designated 5S-Rrna-A2, 5S-Rrna-B2, and 5S-Rrna-D2. The 5S rRNA locus in 1AS is a new finding in Chinese Spring wheat. © 1990 The American Genetic Association.