Physical Mapping of the 5S Ribosomal RNA Gene in Citreae of Aurantioideae Species using Fluorescence in situ Hybridization

Abstract

The location of the 5S ribosomal RNA gene (rDNA) in species from six genera of the Citreae of Aurantioideae was determined using fluorescence in situ hybridization (FISH). A 5S rDNA probe was labeled with biotin-16-dUTP. The probe was detected using a fluorescein isothiocyanate (FITC)-avidin conjugate with chromosomes counterstained with propidium iodide (PI). When the chromosomes were observed under a G filter, PI-stained chromosomes were classified into the following five types based on the number and position of PI-positive (+) bands; B: one telomeric and one proximal band, C: two telomeric bands, D: one telomeric band, E: without bands and Dst: type D with a satellite chromosome. Two 5S rDNA sites were located in type D chromosomes in Citropsis gabunensis, whereas in Citrus reshni, Fortunella japonica, Clymenia polyandra and Swinglea glutinosa they were found in type E chromosomes. In Poncirus trifoliata, three rDNA sites were located together at the proximal PI (+) band of a type B chromosome, one site was located in the proximal region of a type D chromosome, and two sites were located together at the PI (+) band of a type D chromosome.

Molecular characterization of novel Ty1-copia-like retrotransposons in pear (Pyrus pyrifolia)

“…FISH analysis was performed according to a standard method (Ohmido and Fukui 1996;Yamamoto et al 2009). Before hybridization, chromosome samples were treated with 100 ng/mL RNase A (Sigma-Aldrich, Japan) in 2× SSC at 37°C for 60 min; dehydrated through a 70%, 95%, and 99% ethanol series for 5 min each; and dried.…”

Linked 5S and 45S rDNA Sites Are Highly Conserved through the Subfamily Aurantioideae (Rutaceae)

“…Twenty-four of these species, including 37 accessions, also had the number and position of 5S and 45S rDNA identified [Pedrosa et al, 2000;Carvalho et al, 2005;Moraes et al, 2007a, b]. Furthermore, Yamamoto et al [2009] reported a single pair of 5S rDNA sites in chromosomes of Citropsis gabunensis, Citrus reshni, Fortunella japonica, Clymenia polyandra and Swinglea glutinosa and in 3 pairs in Poncirus trifoliata , but they did not investigate the position of 45S rDNA. Likewise, the number of 45S rDNA sites was previously reported for several Citrus species [Kang et al, 2008;Marques et al, 2011] and some related genera [Barros e Silva et al, 2010].…”