Research paperKaryotype analysis of Piptanthus concolor based on FISH with a oligonucleotides for rDNA 5S

- Karyotype analysis of Piptanthus concolor is first executed using FISH method.
- Oligonucleotides ribosomal DNA probe 5S rDNA, a 41 bp fragment is as a novel probe.
- The density and location of signal both 5S rDNA are diverse among individual chromosome of Piptanthus concolor.

The karyotype of Piptanthus concolor was analysed via fluorescence in situ hybridization (FISH) using oligonucleotide probe for ribosomal DNA (rDNA) (5S rDNA, 41 bp). P. concolor had 2n = 18 chromosomes. The karyotype was composed of 3 pairs of metacentric chromosomes (including one pair of satellites), 3 pairs of submetacentric chromosomes, and 3 pairs of subtelocentric chromosomes. 5S rDNA loci were detected in 8 chromosome pairs. The density and location of signals for both 5S rDNA varied among individual chromosomes. High-intensity 5S signals were detected in the short arms of chromosomes 7 and 8, and weak signals were also detected in the long arms of the same chromosomes. For the satellite chromosomes, 17 and 18, the 5S rDNA signal was located at the end of the long arm. The third pair of chromosomes, 9 and 10, also significantly differed from other chromosomes with respect to the 5S rDNA signals observed in the subterminal region. The fourth pair of chromosomes, 11 and 12, had no 5S rDNA signal. The other pairs of chromosomes also exhibited individual signals. Our results provide information that may be beneficial for future cytogenetic studies and could contribute to the physical assembly of the Piptanthus genome.