| Identification of Wheat and rye chromosomes by in
situ hybridization with repeated DNA suquences Y. Mukai and M. Miki Department of Biology, Osaka Kyoiku University, Ikeda, Osaka, Japan The proportion of repeated DNA sequences has been estimated at more than 80% of common wheat DNA. Using technique of in situ hybridization with biotin-labeled probe, repeated DNA sequences proved useful as cytological markers for chromosome identification. In situ hybridization using pSC119 probe containing repeated sequences (120-bp repeated family) from rye heterochromatin was conducted on rye, triticale, and wheat-rye substitutions to identify rye and/or wheat chromosomes. Using high labeling DNA by random primer method and biotin-16-dUTP, high-resolutive in situ plates were obtained. Individual chromosomes of Prolific rye were distinguished from each other by in situ hybridization patterns to pSC119 (Fig. 1). The 120-bp family detected by pSC119 were clustered at 28 sites distributed over the seven chromosomes. In a hexaploid triticale, Rosner six pairs of rye chromosomes were identified (Fig. 2). Rye chromosomes were readly distinguishable from the wheat chromosomes In addition to dark brown labeling of heterochromatic regions, all chromosomes of rye gave light brown color indicating the dispersed nature of the repeated sequences, whereas those of wheat appeared blue. Rayburn and Gill (1985) reported that chromosome 4B (formerly 4A) of wheat had four major hybridization sites, one terminal and two intercalary on the long arm and one terminal on the short arm. They also suggested that chromosome 4B has been stable during the evolution of the polyploid wheats. In chromosome 4B of Rosner, however, an additional interstitial site on the short arm was observed. In situ hybridization to biotin-labeled pSC119 in a 1R(1B) substitution line, Burgas2 was shown in Fig. 3, in which the two rye chromosomes were easily identified. By modifying the amount of biotinylated probe or stringency in hybridization, the tone of color of rye chromosome could be controlled (Fig. 1, Fig. 3). |