tailieunhanh - báo cáo khoa học: " Dynamic distribution patterns of ribosomal DNA and chromosomal evolution in Paphiopedilum, a lady’s slipper orchid"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Dynamic distribution patterns of ribosomal DNA and chromosomal evolution in Paphiopedilum, a lady’s slipper orchid | BMC Plant Biology Dynamic distribution patterns of ribosomal DNA and chromosomal evolution in Paphiopedilum a lady s slipper orchid Lan and Albert Lan and Albert BMC Plant Biology 2011 11 126 http 1471-2229 11 126 12 September 2011 2 BioMed Central Lan and Albert BMC Plant Biology 2011 11 126 http 1471 -2229 11 126 BMC Plant Biology RESEARCH ARTICLE Open Access Dynamic distribution patterns of ribosomal DNA and chromosomal evolution in Paphiopedilum a lady s slipper orchid Tianying Lan and Victor A Albert Abstract Background Paphiopedilum is a horticulturally and ecologically important genus of ca. 80 species of lady s slipper orchids native to Southeast Asia. These plants have long been of interest regarding their chromosomal evolution which involves a progressive aneuploid series based on either fission or fusion of centromeres. Chromosome number is positively correlated with genome size so rearrangement processes must include either insertion or deletion of DNA segments. We have conducted Fluorescence In Situ Hybridization FISH studies using 5S and 25S ribosomal DNA rDNA probes to survey for rearrangements duplications and phylogenetically-correlated variation within Paphiopedilum. We further studied sequence variation of the non-transcribed spacers of 5S rDNA 5S-NTS to examine their complex duplication history including the possibility that concerted evolutionary forces may homogenize diversity. Results 5S and 25S rDNA loci among Paphiopedilum species representing all key phylogenetic lineages exhibit a considerable diversity that correlates well with recognized evolutionary groups. 25S rDNA signals range from 2 representing 1 locus to 9 the latter representing hemizygosity. 5S loci display extensive structural variation and show from 2 specific signals to many both major and minor and highly dispersed. The dispersed signals mainly occur at centromeric and subtelomeric positions which are hotspots for chromosomal .

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