Dynamics of the evolution of orthologous and paralogous portions of a complex locus region in two genomes of allopolyploid wheat
Dynamics of the evolution of orthologous and paralogous portions of a complex locus region in two genomes of allopolyploid wheat
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DOI：
10.1023/b:plan.0000028768.21587.dc
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发表时间：
2004-01-01
影响因子：
5.1
通讯作者：
Anderson, OD
中科院分区：
文献类型：
--
作者：
Kong, XY;Gu, YQ;Anderson, OD
从四倍体小麦（Triticum turgidum）的B基因组中鉴定出两个重叠的细菌人工染色体（BAC）克隆，每个克隆都含有两个高分子量（HMW）谷蛋白基因中的一个，包括复杂的Glu-B1位点。测定了该染色体区域的DNA全序列（285 506 bp）。研究发现，在小麦六倍体d基因组供体Aegilops tauschii的Glu-D1位点上，Glu-1-1和Glu-1-2两个hmw -谷蛋白复合物Glu-B1位点上的两个副ogousx型（Glu-1-1）和y型（Glu-1-2）基因的距离为16.8万bp，而此前报道的Glu-D1位点的距离为5.1万bp。基因间距的差异几乎完全是由于嵌套的反转录转座子簇的插入造成的。另外，两个基因组中HMW谷蛋白及其邻近基因的取向和顺序相同。这些同源区域的比较表明了序列分化的模式和模式，对整个麦类基因组结构和进化具有重要意义。在每个hmw -谷蛋白基因的5'处发现一个重复的球蛋白基因，有助于初步确定导致同源的hmw -谷蛋白x型和y型基因的原始复制事件。两个基因座的基因间区由不同类型和类型的反转录转座子组成，表明这些反转录因子的插入时间是在两个小麦基因组分化之后。此外，在Glu-B1位点的y型hw -谷蛋白基因附近的一个假定的受体激酶基因可能是活跃的，因为它与最近报道的萌发大麦胚乳的ESTs相匹配。在小麦属胚乳ESTs中发现的4个基因表明存在胚乳特异性染色体结构域。
Two overlapping bacterial artificial chromosome (BAC) clones from the B genome of the tetraploid wheat Triticum turgidum were identified, each of which contains one of the two high-molecular-weight (HMW) glutenin genes, comprising the complex Glu-B1 locus. The complete sequence (285 506 bp of DNA) of this chromosomal region was determined. The two paralogousx-type (Glu-1-1) and y-type (Glu-1-2) HMW-glutenin genes of the complex Glu-B1 locus were found to be separated by ca. 168 000 bp instead of the 51 000 bp separation previously reported for the orthologous Glu-D1 locus of Aegilops tauschii, the D-genome donor of hexaploid wheat. This difference in intergene spacing is due almost entirely to be the insertion of clusters of nested retrotransposons. Otherwise, the orientation and order of the HMW glutenins and adjacent genes were identical in the two genomes. A comparison of these orthologous regions indicates modes and patterns of sequence divergence, with implications for the overall Triticeae genome structure and evolution. A duplicate globulin gene, found 5' of each HMW-glutenin gene, assists to tentatively define the original duplication event leading to the paralogous x- and y-type HMW-glutenin genes. The intergenic regions of the two loci are composed of different patterns and classes of retrotransposons, indicating that insertion times of these retroelements were after the divergence of the two wheat genomes. In addition, a putative receptor kinase gene near the y-type HMW-glutenin gene at the Glu-B1 locus is likely active as it matches recently reported ESTs from germinating barley endosperm. The presence of four genes represented only in the Triticeae endosperm ESTs suggests an endosperm-specific chromosome domain.