【作者】 李丹；

【导师】 徐进；

【作者基本信息】 南京林业大学 ， 遗传学， 2010， 硕士

【摘要】 本研究从杉木中克隆了两段端粒相关序列TAS1和TAS2,并对杉科植物墨西哥落羽杉、池杉、落羽杉、中山杉、东方杉的5S rDNA基因进行了克隆测序,与杉科其他植物的5S rDNA基因进行同源性分析。首次应用染色体荧光原位杂交技术在杉木染色体上定位了端粒相关序列TAS1和5S rDNA基因。利用单引物在杉木中进行PCR扩增,得到两段杉木端粒相关序列,在NCBI上进行比对,推测TAS1和TAS2可能来自于杉木不同的染色体,表明即使是同一物种的同一个体,端粒相关序列之间同源性也是很低的,具有很高的多态性。分别对墨西哥落羽杉、池杉、落羽杉、中山杉、东方杉的5S rDNA基因进行克隆测序,与杉木、柳杉和水杉的5S rDNA基因进行同源性分析,表明:杉木与中山杉、东方杉、落羽杉、水杉、池杉的5S rDNA基因区相似度不是很高,与柳杉和墨西哥落羽杉的相似度较低,而柳杉与其他6种树种的相似度最低,亲缘关系最远,说明它们在进化过程中5S rDNA基因变异较大。东方杉5S rDNA基因区与母本墨西哥落羽杉的相似度达到99.2%,与父本柳杉的相似度为84.9%,推测东方杉5S rDNA与母本墨西哥落羽杉的相似度高可能是致同进化现象。而中山杉,水杉、池杉的5S rDNA基因区的相似度达到100%,推测中山杉,水杉、池杉的5S rDNA的致同进化表现基本一致。首次采用杉木端粒相关序列作为探针,利用FISH技术在杉木减数分裂中期Ⅰ染色体上进行定位,发现有4个信号点。用杉木5S rDNA基因作为探针在杉木根尖有丝分裂染色体上进行定位,在细胞核和中期染色体上均发现有2个信号点。更多还原

【Abstract】 In the study, two telomere-associated sequences, TAS1 and TAS2 were isolated from Cunninghamia Lanceolata. The 5S rDNA gene sequences of Taxodium mucronatum、T. ascendens.Brongn、T. distichum、T.distichum×T. mucronatum、T. mucronatum×Cryptomeria fortunei were cloned and sequenced, then compared with other plants. It was the first time to localize the TAS1 and 5S rDNA on Chromosomes of Cunninghamia Lanceolata by FISH (Fluorescence in situ hybridization).Two telomere-associated sequences, TAS1 and TAS2 were isolated from Cunninghamia Lanceolata by single-primed PCR, and compared with the sequences in the NCBI, It presumed that TAS1 and TAS2 might come from different chromosomes of Cunninghamia Lanceolata. It conclusioned that even the same species, the same individual, it was low homology and high polymorphic between TAS DNA sequences.It was cloned and sequenced 5S rDNA of T.mucronatum、T. ascendens.Brongn、T.distichum、T.distichum×T. mucronatum、T.mucronatum×C.fortunei, then compared with C. Lanceolata、C. fortunei and M.glyptostroboides. It was found that C.Lanceolata had low similarity with T. distichum×T. mucronatum、T. mucronatum×C. fortunei、T. distichum、M. glyptostroboides、T. ascendens.Brongn, lower with C. fortunei and T. mucronatum, while C. fortunei had the lowest similarity, had the farthest relationship with other six species. Our results illustrated that there were large variation of 5S rDNA gene. The similarity of 5S rDNA gene region of T. mucronatum×C. fortunei with T. mucronatum was 99.2%, with C. fortunei was 84.9%, It speculated that it was a concerted evolution phenomenon. The similarity of 5S rDNA gene region of T. distichum×T. mucronatum、M. glyptostroboides and T. ascendens.Brongn was 100%, It presumed that the 5S rDNA gene of T. distichum×T. mucronatu、M. glyptostroboides and T. ascendens.Brongn have completely concerted evolution.It was the first time to localize the TAS1 on metaphase chromosome of Cunninghamia Lanceolata by FISH, the results indicated that there were four cross loci. It was localized 5S rDNA which used as a probe on mitotic chromosomes of Cunninghamia Lanceolata, the results indicated that there were two cross signal which had been detected both in the nucleus and metaphase chromosomes.更多还原