Cytogenetic Analysis of Polygala tenuifolia Wild by Different Staining Techniques and Fluorescent In Situ Hybridization

摘要

Karyotype of P. tenuifolia was characterized with emphasis on heterochromatin distribution using Giemsa C-banding, Chromomycin A3 (CMA3), DAPI, silver impregnation and localization of ribosomal (18S-5.8S-26S rDNA) by fluorescence in situ hybridization(FISH). Diploid chromosome complement, 2n = 2_x = 38, consisted of 13 pairs of submetacentric and 6 pairs of metacentric chromosomes. C-banding and silver staining showed a conspicuous bands on the short arms of pair 13, where the secondary constriction(SC) was located. The only GC rich heterochromatin, as revealed by fluorochrome Chromomycin A3 (CMA) staining, was that associated with nucleolar organizer regions (NORs), where 4, 6-diamino-2-phenylindole (DAPI) apparently stained pale. AT rich heterochromatin stained with DAPI was distributed uniformly on all chromosomes. FISH with 45S rDNA probe revealed one 18S-5.8S-26S rDNA loci on secondary constriction of chromosome pair 13, where they corresponded to nucleolar organizer regions. The ribosomal DNA behaviors during the cell cycle were analyzed on interphase nuclei, prophases, metaphases, anaphase and telophase; indicate that the activity of rDNA at individual loci may also vary through different phases.