Fluorescent staining and fluorescence in situ hybridization of rDNA of chromosomes in pear (pyrus spp.)

Abstract

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. pyrif olia × P. ussuriensis var. aromatica (a hybrid of Japanese pear and Iwateyamanashi), and P. mikawana Koid z. (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. © 2012.