Genetic and epigenetic alteration among three homoeologous genes of a class E MADS box gene in hexaploid wheat
Genetic and epigenetic alteration among three homoeologous genes of a class E MADS box gene in hexaploid wheat
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DOI：
10.1105/tpc.107.051813
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发表时间：
2007-06-01
期刊：
影响因子：
11.6
通讯作者：
Murai, Koji
中科院分区：
文献类型：
--
作者：
Shitsukawa, Naoki;Tahira, Chikako;Murai, Koji
面包小麦（Triticum aestivum）是一个六倍体物种，具有A、B和D祖先基因组。大多数面包小麦基因在基因组中作为来自祖先物种的三重同源基因（homoeologs）存在。在这里，我们报告说，遗传和表观遗传的改变发生在小麦类E MADS盒基因的同源。在小麦中发现了两个E类基因，即小麦SEPALLATA（WSEP）和小麦LEAFY船体1（WLHS 1），它们分别与水稻OsMADS 45和OsMADS 1同源。WSEP的3个小麦同源基因具有相似的基因组结构和表达谱。相比之下，WLHS 1的三个同源物显示遗传和表观遗传改变。A基因组WLHS 1同源物（WLHS 1- A）具有结构改变，其中包含一个大的新序列代替K结构域序列。酵母双杂交分析和转基因实验表明，WLHS 1- A蛋白没有明显的功能。B和D基因组同源物WLHS 1- B和WLHS 1- D分别具有完整的MADS盒基因结构，但WLHS 1-B主要通过胞嘧啶甲基化沉默。因此，在三个WLHS 1同源物中，只有WLHS 1- D在六倍体小麦中起作用。这是一种三种同源物受遗传和表观遗传机制差异调节的情况。
Bread wheat ( Triticum aestivum) is a hexaploid species with A, B, and D ancestral genomes. Most bread wheat genes are present in the genome as triplicated homoeologous genes (homoeologs) derived from the ancestral species. Here, we report that both genetic and epigenetic alterations have occurred in the homoeologs of a wheat class E MADS box gene. Two class E genes are identified in wheat, wheat SEPALLATA ( WSEP) and wheat LEAFY HULL STERILE1 ( WLHS1), which are homologs of Os MADS45 and Os MADS1 in rice ( Oryza sativa), respectively. The three wheat homoeologs of WSEP showed similar genomic structures and expression profiles. By contrast, the three homoeologs of WLHS1 showed genetic and epigenetic alterations. The A genome WLHS1 homoeolog (WLHS1- A) had a structural alteration that contained a large novel sequence in place of the K domain sequence. A yeast two-hybrid analysis and a transgenic experiment indicated that the WLHS1- A protein had no apparent function. The B and D genome homoeologs, WLHS1- B and WLHS1- D, respectively, had an intact MADS box gene structure, but WLHS1-B was predominantly silenced by cytosine methylation. Consequently, of the three WLHS1 homoeologs, only WLHS1- D functions in hexaploid wheat. This is a situation where three homoeologs are differentially regulated by genetic and epigenetic mechanisms.