植物45S rDNA的染色体位置的CPD染色和FISH分析

采用PI和DAPI组合(CPD)染色结合45SrDNA探针的荧光原位杂交(FISH)对分属6个科的16种植物的45S rDNA的染色体位置进行了分析。在所有供试植物中,共检测到53个45S rDNA位点。大多数45S rDNA位点分布在染色体的短臂;位于染色体臂内和染色体末端的位点的比例大体相当;多数位于染色体臂内的45S rDNA位点有次缢痕形成,但rDNA重复单位簇所处的位置存在差异。根据45S rDNA所处的染色体臂的不同、距着丝粒远近的差异、形成次缢痕与否以及rDNA重复单位簇相对于次缢痕的位置等特征,将植物的45S rDNA位点划分为12种染色体分布类型。基于我们的结果和其他的报道对45S rDNA位点、核仁组织区(NOR)、次缢痕和随体相互之间的关系进行了分析。

Analysis of the chromosomal location of 45S rDNA in plants by CPD staining together with FISH

The chromosomal location of 45S rDNA in sixteen plant species belonging to six families was analyzed using combined PI and DAPI(CPD)staining together with fluorescence in situ hybridization(FISH)with 45S rDNA probe.Fifty three 45S rDNA sites in total were detected in the tested species.The 45S rDNA sites occurred mainly in the short arms instead of the long arms,and interstitial and terminal 45S rDNA sites appeared at similar frequency.Secondary constrictions appeared in most interstitial 45S rDNA sites,but the orientation of the cluster of rDNA repeats relative to the secondary constriction differed among these interstitial sites.The chromosomal distribution of 45S rDNA sites in the tested plants could be classified into 12 types based on the differences in the chromosomal arm in which 45S rDNA site reside,the distance from centromere to 45S rDNA site,the formation of secondary constriction,and the orientation of the cluster of rDNA repeats.The interrelation among 45S rDNA site,NOR(nucleolar organizing region),secondary constriction,and satellite was analyzed based on our results and other previous reports.