栽培玉米亚种5 S rDNA NTS序列分析及FISH定位方法比较

选取我国7个栽培玉米亚种材料，进行5 S rDNA的非转录间隔区（nontranscribed intergenic spacer,NTS）的序列分析，比较7个亚种材料NTS序列差异并进行聚类分析，探讨其亲缘关系。研究结果表明：7个材料的NTS区GC平均含量为45．67％，核苷酸位点变异位点个数1～15，转换／颠换率为0．83～2．0，特用玉米材料均存在不同程度的缺失；7个材料主要聚为两大类，第一类群中包括甜质、马齿、硬粒、爆裂和蜡质5个亚种材料，第二类群中包括粉质和甜粉2个亚种材料。同时利用荧光原位杂交技术（fluorescence in situ hybridization，FISH）对5 S rDNA进行定位，探针标记分别采用荧光素标记和生物素标记。结果表明：生物素标记检测系统灵敏度高、杂交信号强，更适合于5 S rDNA重复序列的定位检测。

Comparative Analysis of Sequences and the Methods of Physical Mapping by FISH of 5 S rDNA in Subspecies Maize

Nontranscribed intergenic spacer（NTS） sequences in different subspecies maize were analyzed and clustered. The results showed the average GC content（ % ） of 7 NTS regions was 45.67 %. The numbers of variable sites was 1 - 15, ratios of convertion/transition were 0.83 - 2.0. The materials were classified into two groups by cluster analysis. The 5 S rDNA in metaphase chromosomes were localized in different materials by fluorescence in situ hybridization. The probe was labled by fluorescein and biotin methods. The results indicated that the probe labled by biotin-11- dUTP was easier to detect by the fluorescence microscope. This method was more appropriate to localize the repeat sequence like 5 S rDNA in plants.