Gene-containing regions of wheat and the other grass genomes
Gene-containing regions of wheat and the other grass genomes
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DOI：
10.1104/pp.010745
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发表时间：
2002-03-01
期刊：
影响因子：
7.4
通讯作者：
Gill, KS
中科院分区：
文献类型：
--
作者：
Sandhu, D;Gill, KS
基于缺失线的高密度物理图谱显示，小麦（Triticum aestivum）基因组被划分为基因丰富和基因贫乏区室。可用的缺失系将含有基因的区域包括在基因组的约10%内。新出现的序列数据表明，这些可能进一步划分为“迷你”基因丰富和基因贫乏的地区。每个基因丰富区域平均约有10%似乎含有基因。对不同物种的序列分析表明，基因的不均匀分布可能是所有禾本科植物的特征，也许是所有高等生物的特征。物理图谱与遗传连锁图谱的比较表明，在小麦和大麦（大麦）的重组仅限于含基因的区域。基因的数量、基因密度和重组的程度在基因丰富的区域之间变化很大。基因序列、相对区域大小和重组在小麦族内高度保守，在科内中度保守。基因缺失区由逆转录转座子样非转录重复序列和假基因组成。直接比较结果表明，小麦的根密度约为水稻的二分之一。因此，小麦和水稻之间基因组大小的差异主要是由于基因缺失区域的扩增。种、属和科特异性重复序列的存在揭示了不同逆转录转座子随时间的推移对基因组的重复入侵。优先转座到邻近位置以及基因丰富区域侧翼重要基因的存在可能会限制反转录转座子扩增到基因贫乏区域，导致非转录重复序列的串联块。插入失活相邻的逆转录元件和选择似乎发挥了重要作用，在稳定基因组。
Deletion line-based high-density physical maps revealed that the wheat (Triticum aestivum) genome is partitioned into gene-rich and -poor compartments. Available deletion lines have bracketed the gene-containing regions to about 10% of the genome. Emerging sequence data suggest that these may further be partitioned into "mini" gene-rich and gene-poor regions. An average of about 10% of each gene-rich region seem to contain genes. Sequence analyses in various species suggest that uneven distribution of genes may be a characteristic of all grasses and perhaps all higher organisms. Comparison of the physical maps with genetic linkage maps showed that recombination in wheat and barley (Hordeum vulgare) is confined to the gene-containing regions. Number of genes, gene density, and the extent of recombination vary greatly among the gene-rich regions. The gene order, relative region size, and recombination are highly conserved within the tribe Triticeae and moderately conserved within the family. Gene-poor regions are composed of retrotransposon-like non-transcribing repeats and pseudogenes. Direct comparisons of orthologous regions indicated that gone density in wheat is about one-half compared with rice (Oryza sativa). Genome size difference between wheat and rice is, therefore, mainly because of amplification of the gene-poor regions. Presence of species-, genera-, and family-specific repeats reveal a repeated invasion of the genomes by different retrotransposons over time. Preferential transposition to adjacent locations and presence of vital genes flanking a gene-rich region may have restricted retrotransposon amplification to gene-poor regions, resulting into tandem blocks of non-transcribing repeats. Insertional inactivation by adjoining retro-elements and selection seem to have played a major role in stabilizing genomes.