Fluorescent Staining Analysis 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 six cultivars from three species [Pyrus pyrifolia (Burm. F) Nakai (Japanese pear), P. communis L. (European pear), and P. bretschneideri Rehder (Chinese pear)]. Root tips were pretreated in 2 mM 8-hydroxyquinoline at 10°C for 4 h; the chromosome samples were prepared by the enzymatic maceration and air-drying method. All cultivars used in this study had 2n = 34 chromosomes. Chromomycin A3 (CMA) positive (+) bands were observed in telomeric positions of four chromosomes. In some samples, these CMA+bands were observed at satellite positions. 4'-6-diamidino-2-phenylindole (DAPI) negative bands (−) were seen to correspond with CMA+bands. Thirty chromosomes had no CMA+/DAPI−bands. No propidium iodide (PI) bands were observed in any chromosomes. The number and positions of CMA+bands were stable, and there was no difference among the three species.