45S rDNA在多种植物中期染色体上的定位

应用荧光原位杂交技术首次确定了日本小檗（Berberis tkunbergii DC）、车前（Plantago major L．）、野芹菜（Sanicula lamelligera Hance）、荔枝（Litchi chinensis Sonn．）、械树（Acer buergerianum Miq．）、天目琼花（Viburnum sargentii Koehne．）、丹参（Salvia miltorrhiza Bunge．）、榆树（Ulmus pumila L．）中45S rDNA在中期染色体上的位置．根据rDNA的位点数和位置的变化，分为四种类型：①在日本小檗、车前和野芹菜中，荧光信号正好位于随体染色体的次缢痕或端部；②荔枝和械树，分别有1对和3对染色体具随体，但荧光原位杂交却检测到3对和5对染色体上具有杂交信号；③天日琼花，具有4对随体染色体，但仅住其中一对随体上显示了杂交信号；④在丹参和榆树中，有的杂交信号位于着丝粒部位或长臂的末端，杂交信号的数目成奇数．黄瓜（Cucumis sativus L．）的染色体45S rDNA信号正好位于6条染色体的着丝粒部位，这与Dal-Hoe和Hoshi等人的结果是一致的．上述结果表明：45S rDNA可以作为染色体的一个识别指标，对识别染色体的个体性具有一定的参考价值．另外还对45S rDNA位点分布的多态性进行了讨论．

Physical Mapping of 45S rDNA on Metaphase Chromosomes in Several Plant Species

The genomic distribution of ribosomal RNA genes has been determined for the first time by fluorescence in situ hybridization(FISH) in Berberis thunbergii DC.,Plantago major L.,Sanicula lamelligera Hance,Litchi chinensis Sonn.,Acer buergerianum Miq.,Viburnum sargentii Koehne.,Salvia miltiorrhiza Bunge.,and Ulmus pumila L..These species could be divided into four groups based on the difference on the number and sites of their rDNA loci: the fluorescence signals lay in the secondary constrictions or the terminal regions of SAT-chromosomes in B.thunbergii,P.major,and S.lamelligera;3 and 5 pairs of signals were detected in L.chinensis and A.buergerianum,respectively which had 1 and 3 pairs of satellites respectively;there were 4 pairs of SAT-chromosomes in V.sargentii,but only one of them showed hybridization signals;in S.miltiorrhiza and U.pumila,some signals lay in the pericentromeric regions or the end of long arms and the number of rDNA loci was odd.There were six signals in the pericentromeric region in Cucumis sativus L.that agreed with previous reports.Our results indicated that 45S rDNA could be used to identify individual chromosome.The polymorphism of 45S rDNA loci was discussed in this paper.