Location of 45S and 5S rDNA on Barley Chromosomes and FISH Analysis for 5S rDNA on Extended DNA Fibers

With the help of fluorescene in situ hybridization(FISH),we have located and analyzed the sites of the 45S and 5S rDNA on the mitotic metaphase chromosomes of barley (Hordeum vulgare L.).The results indicated that there were two pairs of signs detected for 45S rDNA,each at 1S and 2L.The signal of 5S rDNA was relatively weak,and it was located on 3L.The copy number of 5S rDNA was determined by extended DNA fiber based on DNA fiber fluorescence in situ hybridization (Fiber-FISH) in barley genome.It could be estimated that the copy number was about 408-416 for 5S rDNA.In this study,the variability of number of rDNA in genome among different barley species was discussed.