Abstract: This study examined the physical localizations of the 25S rDNA on the mitotic metaphase chromosomes of seven species in the five sections of Populus, using fluorescence in situ hybridization (FISH) . Four 25 rDNA loci were detected on the chromosomes of five wild diploid species (2n = 2x = 38) , P. tomentosa , P. nigra var. thevestina , P. pseudo-simonii, P. lasiocarpa and P. euphratica . Six 25 rDNA loci were detected on the chromosomes of two wild triploid species (2n= 3x = 57) , P. tomentosa in section Leuce and P. euramericana cv . Wuhei-1 in section Aigeiros . While only one pair of 25 rDNA loci located at the smallest chromosome was detected in P. euphratica chromosomes. Coupled with the approach of common karoytype analysis, this article also discusses the variations of 25S rDNA distribution on Populus chromosomes .

Key words: Populus

摘要： 利用荧光原位杂交技术对杨属( Populus) 植物五个组中二倍体( 2n = 2x = 38 ) 代表种: 毛白杨( P. tomentosa) 、箭杆杨( P. nigra var. thevestina) 、大叶杨( P. lasiocarpa)、小青杨( P. pseudo-simonii ) 、胡杨( P. euphratica) ; 以及所发现的白杨组和黑杨组天然三倍体( 2n = 3x = 57 ) : 毛白杨( P. tomentosa) 、武黑1号( P. euramericana cv . Wuhei-1) 进行了25S rDNA 的染色体定位。二倍体毛白杨、箭杆杨、小青杨和大叶杨都具有4 个25S rDNA 位点, 而胡杨只有2 个较大的25S rDNA 定位于1 对小的染色体上, 白杨和黑杨天然三倍体的两个种各有6 个25S rDNA 位点。同时作者还将杨属植物25S rDNA 的分布变化与常规核型分析结果进行了比较。

关键词: 杨属, 荧光原位杂交, 25S rDNA 定位FONT