慈姑45S rDNA和端粒序列检测及核型分析

Detection of 45S rDNA and Telomere Sequences and Karyotype Analysis of Sagittaria trifolia L.

以45S r DNA和拟南芥型端粒序列为探针对慈姑(Sagittaria trifolia L.)有丝分裂中期染色体进行单色和双色荧光原位杂交分析,并用银染方法检测慈姑45S r DNA位点的表达,最后结合染色体测量数据和45S r DNA杂交信号建立慈姑的核型。结果显示,慈姑的单倍基因组总长度为76.9±1.38μm,最长染色体为11.55±0.10μm,最短染色体为4.54±0.27μm;慈姑的核型公式为:2n=22=2m+2sm+14st+4t,核型不对称性参数CI、A1、A2、As K(%)、AI分别为19.86±11.06、0.72、0.27、78.82、15.29,核型属于Stebbins类型中的3B型。慈姑具有3对45S r DNA位点,分别位于第8、9、10号染色体的短臂末端。拟南芥型端粒序列的杂交信号出现在慈姑每一条染色体的长、短臂末端。银染检测到6个Ag-NOR和6个核仁,表明3对45S r DNA位点在间期核都有表达。本研究结果为药食兼用植物慈姑提供了分子细胞遗传学基础资料。

To provide basic molecular cytogenetic data for Sagittaria trifolia L.,single-and dualcolor fluorescence in situ hybridization（ FISH） analysis on metaphase chromosomes of S.trifolia with 45 S r DNA and Arabidopsis-type telomere sequences were performed, the expression of the 45 S r DNA sites was detected using silver staining,and the karyotype of this species was established by combining chromosome measurements and r DNA FISH signals.The mean haploid karyotype length was 76.90 ± 1.38 μm,the longest chromosome pair was11. 55 ± 0.10 μm and the shortest chromosome pair was 4. 54 ± 0.27 μm. The karyotype asymmetry indices,CI,A1,A2,As K（ %） and AI were 19. 86 ± 11.06,0.72,0.27,78. 82 and15.29,respectively,and the asymmetric karyotype belonged to the 3B type of Stebbins＇ category. Three pairs of 45 S r DNA sites were identified and located at the terminals of the short arms of chromosome pairs 8,9 and 10,respectively. FISH signals from the Arabidopsis-type telomere sequence were observed at the ends of the short and long arms of each chromosome pair. Silver staining showed six Ag-NORs on mitotic chromosomes and one to six nucleoli in interphase cells,indicating that the three pairs of 45 S sites were all expressed at interphase.