25S rDNA和5S rDNA在大白菜中期染色体上的FISH定位

Location of 25S rDNA and 5S rDNA in Chinese Cabbage-pe-tsai Metaphase Chromosome

【目的】确定rDNA在中国大白菜基因组中的位点数目和分布位置,并建立识别大白菜不同染色体的特异标记。【方法】用荧光原位杂交技术对25S rDNA和5S rDNA在大白菜有丝分裂中期染色体进行了定位研究。【结果】在大白菜中期染色体上,分别检出了5对25S rDNA杂交信号和3对5S rDNA杂交信号。对应于大白菜中期染色体形态图,确定5对25S rDNA信号分别分布在大白菜1号染色体长臂(1L)的近末端,2号染色体长臂(2L)的近中部,3号和4号染色体长臂(3L、4L)的近着丝点处和10号染色体的随体上,信号强度为10号>2号>3号和4号>1号;而5S rDNA的3对信号分别位于2号染色体的长臂(2L)和9号、10号染色体的短臂(9S、10S)。【结论】在分子水平上为大白菜部分染色体提供了识别标记。

[Objective] The objective was to determine the number and location of rDNA sites in Chinese cabbage-pe-tsai genome, and identify the special molecular markers related to different chromosomes. [ Method ] Fluorescence in situ hybridization（FISH） technique was used to locate the 25S rDNA and 5S rDNA on the mitotic metaphase chromosomes of Chinese cabbage-pe-tsal. [ Result] Five pairs of hybridization signals of 25S rDNA and three pairs of hybridization signals of 5S rDNA were detected on the metaphase chromosomes. Contrasting the normal karyotype of the diploid Chinese cabbage-pe-tsai, the 25S rDNA hybridization signals were located near the end of 1L, the central section of 2L, the centromere region of 3L and 4L, and the satellite of chromosome 10, respectively. The intensity of hybridization signals was chromosome l0 〉 chromosome 2 〉 chromosome 3 and chromosome 4 〉 chromosome 1. Hybridization signals of 5S rDNA were located on 2L, 9S and 10S. [Conclusion] These results indicated that some molecular markers related to different chromosomes were identified in Chinese cabbage-pe-tsal.