Distribution of rDNA loci and genome differentiation in tetraploid Cynodon

Abstract

The 45S rDNA and 5S rDNA loci encodes for ribosomal RNA. Mapping of rDNA loci has not been reported in Cynodon. We used FISH technique to locate the loci coding for rDNA. Our results showed that the centromeres of three chromosomes had signals of different intensities in the tetraploid bermudagrass line C121. The tetraploid line, C299, had four signals at the centromeres of four chromosomes, with two being strong and two relatively weaker. We found three signals from C121 and four from line C299 about the 5S rDNA sequence. The rDNA signal numbers and sizes indicated existence of genome differentiation in bermudagrass. Combined results of staining pollen mother cells at meiosis indicated that tetraploid bermudagrass has at least two genome types.