Rapid evolution and complex structural organization in genomic regions harboring multiple prolamin genes in the polyploid wheat genome
Rapid evolution and complex structural organization in genomic regions harboring multiple prolamin genes in the polyploid wheat genome
复制标题
多倍体小麦基因组中含有多个谷醇溶蛋白基因的基因组区域的快速进化和复杂的结构组织
DOI：
10.1007/s11103-007-9208-1
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发表时间：
2007-09-01
影响因子：
5.1
通讯作者：
Kong, Xiuying
中科院分区：
文献类型：
--
作者：
Gao, Shuangcheng;Gu, Yong Qiang;Kong, Xiuying
小麦醇溶蛋白基因属于复杂的多基因家族。为了了解结构的复杂性的存储蛋白位点，我们测序和分析的直链区含有醇溶蛋白和低分子量麦谷蛋白基因的A和B基因组的四倍体小麦种，小麦turgidumssp。硬粒。尽管麦醇溶蛋白基因和低分子量麦谷蛋白基因在物理上彼此接近，但它们的组织结构却完全不同。麦醇溶蛋白基因比LMW-麦谷蛋白基因更聚在一起，LMW-麦谷蛋白基因之间的距离要大得多。LMW-麦谷蛋白基因的分离是由于反转录转座子的快速扩增而插入大块重复DNA和在它们之间散布的遗传基因座的存在的结果。通过对小麦同源异型A、B基因组的序列比较，发现基因移动可能是破坏同源异型A、B基因组微共线性的主要因素之一。重复DNA的快速序列重排和差异插入导致基因岛在比较区域中不保守。此外，我们还证明了i型低分子量麦谷蛋白来源于m型基因5′端编码区33个碱基的缺失。我们的研究结果表明，醇溶蛋白基因的多轮片段复制驱动了该区域中ω-醇溶蛋白基因的扩增;这种片段复制可以极大地增加基因组中的重复DNA含量，这取决于原始复制区域中存在的重复DNA的量。
Genes encoding wheat prolamins belong to complicated multi-gene families in the wheat genome. To understand the structural complexity of storage protein loci, we sequenced and analyzed orthologous regions containing both gliadin and LMW-glutenin genes from the A and B genomes of a tetraploid wheat species,Triticum turgidumssp.durum. Despite their physical proximity to one another, the gliadin genes and LMW-glutenin genes are organized quite differently. The gliadin genes are found to be more clustered than the LMW-glutenin genes which are separated from each other by much larger distances. The separation of the LMW-glutenin genes is the result of both the insertion of large blocks of repetitive DNA owing to the rapid amplification of retrotransposons and the presence of genetic loci interspersed between them. Sequence comparisons of the orthologous regions reveal that gene movement could be one of the major factors contributing to the violation of microcolinearity between the homoeologous A and B genomes in wheat. The rapid sequence rearrangements and differential insertion of repetitive DNA has caused the gene islands to be not conserved in compared regions. In addition, we demonstrated that the i-type LMW-glutenin originated from a deletion of 33-bps in the 5′ coding region of the m-type gene. Our results show that multiple rounds of segmental duplication of prolamin genes have driven the amplification of the ω-gliadin genes in the region; such segmental duplication could greatly increase the repetitive DNA content in the genome depending on the amount of repetitive DNA present in the original duplicate region.