Detection of ribosomal RNA genes in soybean, Glycine max (L.) Merr., by in situ hybridization

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Abstract
A biotinylated maize rRNA probe was hybridized to soybean nuclei. Hybridization was detected by using a streptavidin horseradish peroxidase biotin system. The procedure used enabled detection of heterologous complementary 18S and 25S rRNA coding genes in soybean. In diploid cultivars 'Hark' and 'Lincoln' a single pair of satellited chromosomes was present and two binding sites were detected at interphase. In plants trisomic for the satellited chromosome, three sites were observed, and in tetraploid nuclei, four sites were seen. The in situ hybridization results indicated that, for ribosomal RNA genes, Glycine max behaves as a diploid. We discuss the possibility of loss of a pair of satellited chromosomes in the evolution of soybean.Key words: biotin-labeled probe, rRNA genes, ploidy, Glycine max.