Common wheat ( Triticum aestivum L.) is an allohexaploid, consisting of three different genomes (Au, B and D ) which are genetically closely related. Genomic DNA of the three possible genome donors, T. urartu Thum., Aegilops speltoides Tausch and Ae. tauschii Coss.，were employed as probes to hybridize with the diploid genomic DNA digested by Eco RⅠand Hin dⅢ respectively. Both the hybridization strength and band patterns among the genomes would be good indicators of genome relationships. Combining distr ibution data of some repetitive DNA sequences cloned from T. urartu in the three genomes, the authors draw a conclusion that Au and D are more closely related to each other than either one to the B genome. Genomic in situ hybridization (GISH) of T. aestivum cv. Chinese Spring with genomic DNA probes of the three diploid progenitors respectively indicated that the three genomes could be discriminated clearly via GISH. The signals on the chromosomes of Au and D genomes were even. However, when Ae. speltoides DNA was used as probe, there were very strong cross hybridization and the signals condensed on some areas of the metaphasic chromosomes. In the interphase nucleus, the chromatin of B genome dispersed on the same region and the signals on the homologous chromosomes distributed symmetrically. Rich repetitive DNA sequences in B genome, especially the tandem repetitives, perhaps take an important role for the formation of the special hybridization pattern. The main difference between B and the other two genomes probably is in the repetitive DNA sequences.
普通小麦三个基因组之间的遗传关系及原位杂交分析
李大勇1,2 张学勇1* 杨继2 饶广远2
（1. 中国农业科学院作物品种资源研究所，农业部作物种质资源与生物技术重点实验室，北京100081；
2. 北京大学生命科学学院，北京100871）
摘要：以普通小麦 (Triticumaestivum L .)的 3个可能的二倍体供体种 (乌拉尔图小麦 (T .urartu Thum .)、拟斯卑尔脱山羊草 (Aegilopsspeltoides Tausch)和粗山羊草 (Ae.tauschii Coss .) )的基因组DNA为研究对象 ,通过它们之间的相互杂交 ,比较杂交强度以及泳道中带纹的不同 ,并结合部分DNA重复序列在基因组间含量差异的数据 ,得出结论 :Au 和D基因组的关系相对较近。分别以这三个二倍体种的基因组DNA为探针 ,与普通小麦中国春 (T .aestivumL .cv .ChineseSpring)根尖细胞进行基因组原位杂交 (GISH) ,可以清晰地识别出 3个基因组。Au 和D基因组的染色体都呈现均匀的杂交信号 ,但以拟斯卑尔脱山羊草基因组DNA为探针时 ,发现交叉杂交现象十分显著 ,并且杂交信号区域化分布 ,呈现明显的重复序列的特征。在间期核中 ,来自不同基因组的染色质占据不同的空间。我们认为 ,造成B基因组染色体非均匀杂交现象的主要原因 ,可能是因为该基因组中含有更为丰富的串联重复序列 ,B与Au、D基因组的差异也可能主要体现在重复序...
关键词： 小麦；基因组；DNA重复序列；亲缘关系；基因组原位杂交（CISH）
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