2012 Volume 81 Issue 1 Pages 35-40
Fluorescent banding patterns of pear chromosomes were determined from samples taken from root tips of open-pollinated seedlings of Pyrus pyrifolia (Burm. F) Nakai (Japanese pear), P. calleryana Decne. (Callery pear), P. pyrifolia × P. ussuriensis var. aromatica (a hybrid of Japanese pear and Iwateyamanashi), and P. mikawana Koidz. (Toyotomi Nashi). All accessions used in this study had 2n = 34 chromosomes. Chromomycin A3 (CMA)-positive (+) bands were observed in telomeric positions of four chromosomes in all accessions. 4'-6-diamidino-2-phenylindole (DAPI)-negative bands (−) corresponded with CMA+ bands. Fluorescence in situ hybridization (FISH) was conducted using open-pollinated seedlings of ‘Osa Gold’ (Pyrus pyrifolia) and Toyotomi Nashi (P. mikawana) as materials. Four out of six 18S-5.8S-25S ribosomal RNA gene (rDNA) sites corresponded with CMA+/DAPI− bands. The 5S rDNA sites were detected in centromeric positions of two chromosomes. Two centromeric 5S rDNA and six telomeric 18S-5.8S-25S rDNA sites were located on different chromosomes as determined from the results of multi-color FISH.
