[Analysis of the chromosomes of S. bicolor x S. propinquum and S. dochna x S. propinquum by FISH].

ABSTRACT

By means of fluorescence in situ hybridization (FISH), we located and analyzed the sites of the 45S rDNA on the F1 hybrids of S. bicolor x S. propinquum and S. dochnaxS.propinquum. Two signals of 45S rDNA were mapped on the mitotic metaphase chromosomes in the F1 hybrids, respectively, and one signal was present on a bivalent during meiotic of synaptene, diakinesis, and metaphase I. We inferred that the two mitotic chromosomes carrying 45S rDNA were homologous pairs. Considering the signals of 45S rDNA location during meiotic process, chromosome pairing of these two F1 hybrids was normal with an average pairing configuration of 2n=2x=20 (10 II). Our results indicated that 45S rDNA could provide a landmark for identification of individual chromosome during meiosis indirectly.