45S和5S rDNA序列在20种葫芦科植物染色体上的定位

Localization of 45S and 5S rDNA sequences on chromosomes of 20 species of Cucurbitaceous plants

【目的】了解45S和5S rDNA序列在20种葫芦科Cucurbitaceae植物基因组中位点数目和分布特点,为研究葫芦科植物核型、遗传育种和进化分类等提供依据。【方法】采用改进的荧光原位杂交(FISH)法,在45S rDNA和5S rDNA的5′端进行荧光修饰,对20种葫芦科植物中期染色体进行45S和5S rDNA的物理定位,在Nikon 80i荧光显微镜下观察,冷CCD收集图像并分析。【结果】确定了金瓜Gymnopetalum chinense、波棱瓜Herpetospermum pedunculosum、葫芦Lagenaria siceraria、木鳖子Momordica cochinchinensis、云南木鳖Momordica dioica、西葫芦Cucurbita pepo、蛇瓜Trichosanthes anguina、糙点栝楼Trichosanthes dunniana、全缘栝楼Trichosanthes ovigera、钮子瓜Zehneria maysorensis、红瓜Coccinia grandis和佛手Sechium edule等12种植物45S rDNA和5S rDNA荧光位点在中期染色体上的数量、位置和特征,在这些植物中分别检测到3、7、2、4、2、5、3、3、5、1、2和2对45S rDNA,检测到2、1、1、1、1、2、1、1、1、1、1和1对5S rDNA。20种植物中,45S rDNA和5S rDNA在染色体短臂、短臂顶端和着丝点等位置均有分布。【结论】FISH是葫芦科植物构建精细核型的有效工具,可帮助判断随体、鉴别染色体和鉴定同源染色体,是核型分析的有力佐证。

【Objective】To study the number and distribution characteristics of 45S and 5S rDNA sequences in the genome of 20 species of Cucurbitaceae plants,and provide a basis for studying the karyotype,genetic breeding and evolutionary classification of Cucurbitaceae plants.【Method】Using improved fluorescence in situ hybridization(FISH)method,the 45S and 5S rDNA probe sequences were modified by fluorescence at the 5′ends,and the physical locations of 45S and 5S rDNA in the metaphase chromosomes of 20 species of Cucurbitaceae plants were determined.The chromosomes were observed under the Nikon 80 i fluorescence microscope,and images were collected by cold CCD and then were analyzed.【Result】Numbers,locations and characteristics of 45S rDNA and 5S rDNA fluorescence sites on the metaphase chromosomes of 12 plants including Gymnopetalum chinense,Herpetospermum pedunculosum,Lagenaria siceraria,Momordica cochinchinensis,Momordica dioica,Cucurbita pepo,Trichosanthes anguina,Trichosanthes dunniana,Trichosanthes ovigera,Zehneria maysorensis,Coccinia grandis and Sechium edulewere were defined.We detected 3,7,2,4,2,5,3,3,5,1,2 and 2 pairs of 45S rDNA from these 12 plants respectively,and detected 2,1,1,1,1,2,1,1,1,1,1 and 1 pairs of 5S rDNA respectively.The 45 S rDNA and 5S rDNA of 20 plants were found to be located on short arms of chromosomes,terminal ends of short arms or centromeres.【Conclusion】FISH is an effective tool for building fine karyotypes of Cucurbitaceae plants.It can help to analyze the random body,differentiate chromosome and identify homologous chromosomes,and therefore provides strong evidence for karyotype analysis.