中文摘要：

【目的】为了探明普通西瓜种（Citrullus lanatus）3个变种间的亲缘关系和进化与驯化过程，【方法】利用双色荧光原位杂交技术（fluorescence in situ hybridization，FISH），将核糖体45SrDNA和5SrDNA在11份栽培变种（Citrulluslanotus subsp．vulgaris）、2份Egusi变种（C．1anatus subsp．mucosospermus）和3份Citroides变种（Clanatus subsp．1ana-tus）有丝分裂中期染色体上进行了定位研究。11份栽培变种西瓜和2份Egusi类型西瓜都含有2对45SrDNA位点和1对5SrDNA位点，3份Citroides变种都含有1对45SrDNA位点和2对5SrDNA位点。【结果】结果表明，普通西瓜种3个变种内部各基因型间具有相同的45SrDNA和5SrDNA分布模式，栽培变种和Egusi变种具有相同的分布模式，但它们均与Citroides变种存在明显差异，说明栽培变种与Egusi变种之间的亲缘关系更近一些。【结论】rDNA序列分布分析为在分子细胞学水平开展栽培西瓜的进化与驯化分析提供了证据。

英文摘要：

[Objective] The objective of the study is to investigate the genetic relationship ,the process of evolution and domestication in watermelon. [Method]Both 45S rDNA and 5S rDNA were used as probes in the double fluorescence in situ hybridization （FISH） to be localized on chromosomes in 16 genotypes rep- resenting three subspecies. There are two pairs of 45S rDNA loci and one pair 5S rDNA locus in C. lanatus subsp. Vu/gar/s and subsp. Mucosospermus. C. lanatus subsp, lanatus possess one pair 45S rDNA locus and two pairs of 5S rDNA loci. [Result] The result showed that genotypes belonging to one subspecies have similar rDNA distribution pattern, and there was no significant differences between C.lanatus subsp. Vulgaris and C. lanatus subsp. Mucosospermus. C. lanatus subsp, lanatus is quiet different from the other two subspecies in the number and position of rDNAs sites. It is suggested that the distance between C. lanatus subsp. Vulgaris and C. lanatus subsp. Mucosospermus are closer than that of C. lanatus subsp. Lanatus. [Conclusion]The distribution analysis of rDNA sequences provides evidence in evolution and domestication for cultivated watermelon in molecular biology level.