【作者】 蔡清；

【导师】 王晓茹；

【作者基本信息】 中国科学院研究生院（植物研究所） ， 植物学， 2006， 博士

【摘要】 松属植物的基因组十分庞大(大于20000Mbp),其中约90%是由重复序列组成的,我们对其结构和组成仍知之甚少。松属在系统分类上分为两个亚属:单维管束亚属和双维管束亚属。基因组大小研究发现单维管束亚属植物的基因组更大。rDNA作为一类有功能的多基因家族重复序列,其自身特性决定了它在基因组研究中的重要性。FISH技术为rDNA在染色体上物理定位提供了有力的工具。尽管现在对松属rDNA FISH已有不少报道,但主要集中在双维管束亚属,对单维管束亚属的研究几乎是空白。本研究选择5个单维管束亚属松属植物P. bungeana, P. koraiensis, P. armandii, P. wallichiana, P. strobus,进行rDNA FISH研究。旨在弄清18S-25S rDNA和5S rDNA在单维管束亚属植物染色体上的位点数目和分布模式。结合前人对松属双维管束亚属植物的工作,对单、双维管束亚属植物之间rDNA FISH结果进行比较,从而可以从整体上认识松属植物的18S-25S rDNA和5S rDNA在染色体上的分布式样。在此基础上进一步探讨18S-25S rDNA和5S rDNA这些重复序列在松属植物基因组结构和组成中的地位和作用。本研究主要结果如下:1.rDNA FISH在松属染色体核型分析中的作用本研究中5种松属单维管束亚属植物染色体数目均为2n=24,除最短一条染色体为亚中部着丝粒染色体外,其余11条均为中部着丝粒染色体,长度和臂比也十分接近,同源染色体的不容易鉴定,很难排出精确的核型。在我们的研究结果中,5个松属植物中,除了白皮松外,18S-25S rDNA和5S rDNA分布在12对染色体中的10对染色体上,这些位点可作为染色体标记,大大提高了同源染色体鉴定的准确度,但是染色体之间排序问题依然没有很好地解决。核型比较认为种间是否存在部分同源染色体关系也不是十分明确,仅Ⅺ号和Ⅻ号染色体有这种关系,这主要由于Ⅺ号和Ⅻ号染色体容易准确地鉴别出来。核型分析的精确仍有待增加标记来提高。2.rDNA位点数目在松属两个亚属间的比较及其与基因组大小的关系松属植物18S-25S rDNA位点通常为5-10个,5S rDNA位点为1-4个。其中单维管束亚属18S-25S rDNA位点通常为9-10个(除白皮松为4个外),5S rDNA位点为2- 4个;双维管束亚属为18S-25S rDNA位点通常为5-10个,5S更多还原

【Abstract】 Pines have large genomes (>20000) composed of 90% highly repetitive DNA. The genus Pinus is divided into two subgenera: Strobus (Haploxylon) and Pinus (Diploxylon). Early investigations have shown that members of the subgenus Strobus generally have lager genomes than those of the subgenus Pinus. The genome structure of pines, however, is still poorly understood, as is the differentiation between the two subgenera at the genome level. Characterized as multigene families, the tandem repeated genes encoding 18S-25S and 5S ribosomal RNA are major components of the repetitive DNA in plant genome. Fluorescence in situ hybridization (FISH) has proved to be useful tool for chromosomal localization of 18S-25S rDNA and 5S rDNA. Although there have been a few reports available on rDNA FISH in Pinus species, almost all of them are on subgenus Pinus. There is virtually no report till today on the rDNA FISH characterization in subgenus Strobus. In this study, the 18S-25S rDNA and 5S rDNA were localized simultaneously on metaphase chromosomes of five species of subgenus Strobus, P. bungeana, P. koraiensis, P. armandii, P. wallichiana, and P. strobus by FISH. Combined with previous rDNA FISH reports on those species of subgenus Pinus, the comparison of the 18S-25S rDNA and 5S rDNA loci number and localization pattern between the two subgenera can be made, which is necessary to generalize the rDNA loci distribution pattern in Pinus. This study aimed to explore the genome organization and structure of Pinus. The main results and conclusions are followings:1. The karyotype analysis with 18S-25S rDNA and 5S rDNA markers更多还原